CN113285349A - Micro-ring laser array and manufacturing method thereof - Google Patents

Abstract

The invention discloses a micro-ring laser array and a manufacturing method thereof, wherein the micro-ring laser array comprises: a silicon-on-insulator, the silicon-on-insulator comprising: the silicon-based composite material comprises a first layer of silicon material, a second layer of silicon material and a first silicon dioxide layer, wherein the first layer of silicon material and the second layer of silicon material are oppositely arranged, and the first silicon dioxide layer is positioned between the two layers of silicon materials; a plurality of laser output units disposed on the silicon-on-insulator; the laser output unit includes: a micro-ring cavity laser and a waveguide; the micro-ring cavity laser is provided with an active area for emitting laser; the micro-ring cavity lasers have different sizes so as to emit laser with different wavelengths; the silicon-on-insulator has a plurality of device regions exposing the first surface; the device areas are not overlapped and are used for arranging the micro ring cavity lasers, and the micro ring cavity lasers correspond to the device areas one to one; the second layer of silicon material includes a plurality of mutually independent waveguides. The scheme can realize the directional output of laser by a radial coupling conical silicon waveguide structure.

Description

Micro-ring laser array and manufacturing method thereof

Technical Field

The invention relates to the technical field of semiconductor lasers, in particular to a micro-ring laser array and a manufacturing method thereof.

Background

Silicon-based optical interconnects are currently being developed towards Tb/s scale throughput to meet the greatly increased traffic demands of data centers. In large-scale silicon-based optical interconnects, monolithically integrated multiwavelength laser arrays (MWLAs) are very attractive for implementing compact, low-cost, and reliable laser sources in Dense Wavelength Division Multiplexing (DWDM) applications. The micro-ring cavity laser has the characteristics of low threshold value, small volume, easy integration, dynamic mode operation and the like, and is an ideal light source with high performance and low power consumption in a DWDM system. However, due to the strict circular symmetry and total internal reflection in the micro-ring cavity, the directional output of the laser is limited, and the requirements of the all-optical network and the photoelectron information field on the output light power of the semiconductor laser light source cannot be met.

Disclosure of Invention

In view of this, the present invention provides a micro-ring laser array and a method for manufacturing the same, which can realize directional output of laser light by radially coupling a tapered silicon waveguide structure.

In order to achieve the above purpose, the invention provides the following technical scheme:

a micro-ring laser array, the micro-ring laser array comprising:

a silicon-on-insulator, the silicon-on-insulator comprising: the silicon-based composite material comprises a first layer of silicon material, a second layer of silicon material and a first silicon dioxide layer, wherein the first layer of silicon material and the second layer of silicon material are oppositely arranged, and the first silicon dioxide layer is positioned between the two layers of silicon materials;

a plurality of laser output units disposed on the silicon-on-insulator; the laser output unit includes: a micro-ring cavity laser and a waveguide; the micro-ring cavity laser is provided with an active area for emitting laser; the micro-ring cavity lasers have different sizes so as to emit laser with different wavelengths; in a first direction, the waveguide is arranged opposite to the active region of the corresponding micro-ring cavity laser; the first direction is the extending direction of the waveguide and is parallel to the first silicon dioxide layer;

the surface of the first layer of silicon material facing the first silicon dioxide layer is a first surface; the silicon-on-insulator has a plurality of device regions exposing the first surface; the device areas are not overlapped and are used for arranging the micro ring cavity lasers, and the micro ring cavity lasers correspond to the device areas one to one;

the second layer of silicon material includes a plurality of mutually independent waveguides.

Preferably, in the micro ring laser array, the geometric centers of the micro ring cavity lasers are located on the same straight line;

the waveguides are located on the same side of the straight line, and the extending directions of the waveguides are parallel.

Preferably, in the above micro ring laser array, the micro ring laser has a micro ring resonator, and the ring widths of the micro ring resonators are the same and the outer diameters thereof are different; and the edge distances of two adjacent micro-ring cavity lasers are the same.

Preferably, in the micro ring laser array, in the laser output unit, a preset gap is formed between the micro ring cavity laser and the waveguide, and the preset gap is filled with a second silicon dioxide layer.

Preferably, in the micro-ring laser array, the length of the predetermined gap in the first direction is 0.1-0.3 μm.

Preferably, in the above-described micro-ring laser array, the waveguide includes an integrated input portion and output portion;

in the same laser output unit, the input part faces the micro ring cavity laser, the output part faces away from the micro ring cavity laser, the width of the input part is gradually reduced in the first direction, and the micro ring cavity laser points to the waveguide in the first direction.

Preferably, in the above micro ring laser array, in the second direction, the micro ring cavity laser includes a transition layer, an N-type ohmic contact layer, a lower confinement layer, a lower waveguide layer, the active region, an upper waveguide layer, an upper confinement layer, and a P-type ohmic contact layer, which are sequentially stacked on the first surface;

wherein the second direction is directed from the first layer of silicon material to the second layer of silicon material.

The invention also provides a manufacturing method of the micro-ring laser array, which comprises the following steps:

providing a silicon-on-insulator, the silicon-on-insulator comprising: the silicon-based composite material comprises a first layer of silicon material, a second layer of silicon material and a first silicon dioxide layer, wherein the first layer of silicon material and the second layer of silicon material are oppositely arranged, and the first silicon dioxide layer is positioned between the two layers of silicon materials;

patterning the silicon-on-insulator, patterning the second layer of silicon material into a plurality of waveguides, and forming a plurality of device regions with exposed first surfaces on the first silicon dioxide layer; the first surface is a surface of the first layer of silicon material facing the first silicon dioxide layer; the device regions do not overlap;

forming a plurality of micro ring cavity lasers which are in one-to-one correspondence with the waveguides in the device area, wherein the micro ring cavity lasers are in one-to-one correspondence with the device area;

wherein a plurality of laser output units are arranged on the silicon-on-insulator; the laser output unit includes: the micro-ring cavity laser and the waveguide; the micro-ring cavity laser is provided with an active area for emitting laser; the micro-ring cavity lasers have different sizes so as to emit laser with different wavelengths; in a first direction, the waveguide is arranged opposite to the active region of the corresponding micro-ring cavity laser; the first direction is the extending direction of the waveguide and is parallel to the first silicon dioxide layer.

Preferably, in the above manufacturing method, the method for patterning the silicon on insulator includes:

cleaning the silicon on insulator;

etching the second layer of silicon material until the first silicon dioxide layer is exposed to form a plurality of waveguides;

and etching and removing part of the first silicon oxide layer until the first silicon layer is exposed, and forming a plurality of device regions.

Preferably, in the above manufacturing method, a method of forming the micro-ring cavity laser includes:

forming a mask layer covering the waveguide, wherein the mask layer exposes the device area;

forming an epitaxial layer in the device region, wherein the epitaxial layer comprises a transition layer, an N-type ohmic contact layer, a lower limiting layer, a lower waveguide layer, the active region, an upper waveguide layer, an upper limiting layer and a P-type ohmic contact layer which are sequentially formed on the first surface;

etching the epitaxial layer of the device region to form a micro-ring resonant cavity; etching until the N-type ohmic contact layer is exposed, wherein the exposed part of the N-type ohmic contact layer is arranged outside the micro-ring resonant cavity;

forming a third silicon dioxide layer, wherein the third silicon dioxide layer covers the resonant cavity and the N-type ohmic contact layer;

and forming a P electrode connected with the P-type ohmic contact layer and an N electrode connected with the N-type ohmic contact layer.

As can be seen from the above description, in the micro ring laser array and the method for manufacturing the same according to the technical solution of the present invention, the micro ring cavity laser array is a multi-wavelength silicon-based micro ring cavity laser array monolithically integrated on a silicon-based optoelectronic chip, and a plurality of laser output units are manufactured on the same silicon on insulator, where in the laser output units, the micro ring cavity laser outputs laser light through a corresponding waveguide, so as to implement directional laser output; and a plurality of laser output units are manufactured on the basis of the same silicon-on-insulator, and the first layer of silicon material is used as a silicon substrate and can be suitable for a silicon-based optical interconnection system; the laser output units are arranged on the same silicon-based substrate, the direct epitaxial growth process is simple, the silicon-based photonic devices can be conveniently stacked, packaged and manufactured in a large scale and at low cost, and the process can be compatible with the existing CMOS process.

Drawings

In order to more clearly illustrate the embodiments of the present application or technical solutions in related arts, the drawings used in the description of the embodiments or prior arts will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

The structures, proportions, and dimensions shown in the drawings and described in the specification are for illustrative purposes only and are not intended to limit the scope of the present disclosure, which is defined by the claims, but rather by the claims, it is understood that these drawings and their equivalents are merely illustrative and not intended to limit the scope of the present disclosure.

Fig. 1 is a schematic perspective view of a micro-ring laser array according to an embodiment of the present invention;

fig. 2 is a top view of a laser output unit according to an embodiment of the present invention;

fig. 3 is a schematic material structure diagram of a micro ring cavity laser according to an embodiment of the present invention;

fig. 4-25 are process flow diagrams of a method for fabricating a micro-ring laser array according to an embodiment of the present invention;

FIG. 26 is a diagram illustrating the mode TE in the micro-ring resonator obtained by numerical calculation using three-dimensional finite difference time domain (3D-FDTD) according to an embodiment of the present invention_50,1The transverse light field profile of;

fig. 27 is a curve of variation of lasing wavelength with microring radius at a fixed microring width obtained by numerical calculation using a 3D-FDTD method according to an embodiment of the present invention;

fig. 28 is a longitudinal optical field distribution diagram in a Si waveguide at different waveguide thicknesses numerically calculated using a 3D-FDTD method according to an embodiment of the present invention.

Detailed Description

Embodiments of the present application will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the application are shown, and in which it is to be understood that the embodiments described are merely illustrative of some, but not all, of the embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Silicon-based optical interconnects are currently being developed towards Tb/s scale throughput to meet the greatly increased traffic demands of data centers. In large-scale silicon-based optical interconnects, monolithically integrated multiwavelength laser arrays (MWLAs) are very attractive for implementing compact, low-cost, and reliable laser sources in Dense Wavelength Division Multiplexing (DWDM) applications. The micro-ring cavity laser has the characteristics of low threshold value, small volume, easy integration, dynamic mode operation and the like, and is an ideal light source with high performance and low power consumption in a DWDM system. However, due to the strict circular symmetry and total internal reflection in the micro-ring cavity, the directional output of the laser is limited, and the requirements of the all-optical network and the photoelectron information field on the output light power of the semiconductor laser light source cannot be met.

Evanescent coupling of the optical waveguide and the microcavity laser is an important way for realizing effective light output of the laser, and the evanescent coupling method not only can avoid damage to a cavity caused by directly leading out an output structure on a microcavity, but also can independently control and optimize the microcavity laser and the waveguide.

For example, in the four-wavelength InP-based AlGaInAs microdisk laser array of the in-plane transverse coupling bus waveguide proposed in the prior art, the radius of the microdisk is 10.1-10.4 μm, the spacing is 0.1 μm, the laser array realizes 1550nm wavelength continuous wave lasing at room temperature, and the wavelength spacing is about 3-4 nm. However, the laser array is not fabricated on a silicon substrate, and is difficult to apply in silicon-based optical interconnect systems.

Later, a sixteen-wavelength Si-based hybrid integrated AlGaInAs micro-disk laser array of a vertical coupling SOI bus waveguide is provided, but the silicon-based hybrid integration is mainly realized through a bonding mode, the bonding process is complex, the mass and low-cost packaging and manufacturing of silicon-based photonic devices are not facilitated, and the compatibility with the existing CMOS process is poor.

In the coupling mode, the microcavity laser array is based on a structure in which a microcavity and a bus waveguide are transversely coupled, and has the disadvantages that energy output by microcavity coupling is split into two output directions through clockwise and counterclockwise cavity modes, so that each output direction in the waveguide only contains half of total laser output power, and the coupling efficiency is low and the directivity is poor. In addition, the hybrid integrated micro-cavity laser array has a relatively outstanding heat dissipation problem, and the micro-cavity laser array of the transverse coupling bus waveguide also has multiple difficulties in subsequent links such as beam shaping, multi-beam bundling and output coupling.

Accordingly, the present invention provides a micro-ring laser array and a method for fabricating the same, the micro-ring laser array comprising:

a silicon-on-insulator, the silicon-on-insulator comprising: the silicon-based composite material comprises a first layer of silicon material, a second layer of silicon material and a first silicon dioxide layer, wherein the first layer of silicon material and the second layer of silicon material are oppositely arranged, and the first silicon dioxide layer is positioned between the two layers of silicon materials;

a plurality of laser output units disposed on the silicon-on-insulator; the laser output unit includes: a micro-ring cavity laser and a waveguide; the micro-ring cavity laser is provided with an active area for emitting laser; the micro-ring cavity lasers have different sizes so as to emit laser with different wavelengths; in a first direction, the waveguide is arranged opposite to the active region of the corresponding micro-ring cavity laser; the first direction is the extending direction of the waveguide and is parallel to the first silicon dioxide layer;

the surface of the first layer of silicon material facing the first silicon dioxide layer is a first surface; the silicon-on-insulator has a plurality of device regions exposing the first surface; the device areas are not overlapped and are used for arranging the micro ring cavity lasers, and the micro ring cavity lasers correspond to the device areas one to one;

the second layer of silicon material includes a plurality of mutually independent waveguides.

The invention further improves the output optical power of the semiconductor laser by monolithically integrating the micro-ring laser array on the silicon substrate in a planar linear arrangement mode and radially coupling the conical silicon waveguide at the edge of the micro-ring cavity laser, and simultaneously ensures the consistency of the light-emitting directions of the micro-ring laser array to realize the directional output of laser.

As can be seen from the above description, in the micro ring laser array and the method for manufacturing the same according to the technical solution of the present invention, the micro ring cavity laser array is a multi-wavelength silicon-based micro ring cavity laser array monolithically integrated on a silicon-based optoelectronic chip, and a plurality of laser output units are manufactured on the same silicon on insulator, in the laser output units, the micro ring cavity laser outputs laser light through a corresponding waveguide, so as to implement directional laser output; and a plurality of laser output units are manufactured on the basis of the same silicon-on-insulator, and the first layer of silicon material is used as a silicon substrate and can be suitable for a silicon-based optical interconnection system; the laser output units are arranged on the same silicon-based substrate, the direct epitaxial growth process is simple, the silicon-based photonic devices can be conveniently stacked, packaged and manufactured in a large scale and at low cost, and the process can be compatible with the existing CMOS process.

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, the present application is described in further detail with reference to the accompanying drawings and the detailed description.

Referring to fig. 1 to fig. 3, fig. 1 is a schematic perspective structural diagram of a micro-ring laser array according to an embodiment of the present invention, fig. 2 is a top view of a laser output unit according to an embodiment of the present invention, and fig. 3 is a schematic material structural diagram of a micro-ring laser according to an embodiment of the present invention.

As shown in fig. 1 to 3, the micro-ring laser array includes:

a silicon-on-insulator, the silicon-on-insulator comprising: a first layer of silicon material 11 and a second layer of silicon material 13 which are oppositely arranged, and a first silicon dioxide layer 12 which is positioned between the two layers of silicon materials;

a plurality of laser output units 20 disposed on the silicon-on-insulator; the laser output unit 20 includes: the micro ring cavity laser 21 and the waveguide 22, wherein one micro ring cavity laser 21 and the corresponding waveguide 22 are a laser output unit 20; the micro-ring cavity laser 21 is provided with an active area 35 for emitting laser light; the micro-ring cavity laser 21 has different sizes so as to emit laser with different wavelengths; in the first direction, the waveguide 22 is arranged opposite to the active region 35 of the corresponding micro-ring cavity laser 21; the first direction is the extending direction of the waveguide 22 and is parallel to the first silicon dioxide layer 12;

the surface of the first layer of silicon material 11 facing the first silicon dioxide layer 12 is a first surface; the silicon-on-insulator has a plurality of device regions exposing the first surface; the device areas are not overlapped and are used for arranging the micro ring cavity lasers 21, and the micro ring cavity lasers 21 correspond to the device areas one by one;

the second layer of silicon material 13 comprises a plurality of mutually independent waveguides 22.

In the embodiment of the invention, the geometric centers of the micro-ring cavity lasers 21 are positioned on the same straight line; the waveguides 22 are located on the same side of the straight line, and the extending directions of the waveguides 22 are parallel.

The micro ring cavity laser 21 has a micro ring cavity, the ring widths of the micro ring cavity are the same, the outer diameters of the micro ring cavity are different, and the inner diameters of the micro ring cavity are also different; the edge distances of two adjacent micro-ring cavity lasers 21 are the same and are both larger than 0.5 μm.

In the embodiment of the present invention, each micro ring cavity laser 21 has different inner and outer radii but the same ring width, the ring width may be 1.0 μm, and the outer radius R_outCan be 2.7-3.9 μm, and when the outer radius interval is 0.2 μm, the lasing wavelength of each micro-ring cavity laser 21 is in the 1.3 μm band and the wavelength interval is uniform, and is 2-3 nm.

It should be noted that, under the condition that the ring widths of the micro-ring cavity laser 21 are the same, the equidistant lasing wavelength can be realized by changing the inner and outer radii of the micro-ring resonant cavity; the light-emitting directions of the micro ring cavity lasers 21 are the same and face the first direction, and the first direction is directed to the waveguide 22 by the micro ring cavity lasers 21; the central height of the waveguide 22 is aligned with the active region 35 of the micro-ring cavity laser 21, the central height is determined by the thickness of each layer of semiconductor material in the laser material structure, and the thickness of SiO between the micro-ring cavity laser 21 and the waveguide 22 is 0.1-0.3 μm₂The materials are separated, and laser light in the micro-ring cavity laser 21 enters the waveguide 22 in an evanescent wave coupling mode.

In the embodiment of the present invention, a preset gap g is formed between the micro-ring cavity laser 21 and the waveguide 22, and the second silicon dioxide layer 15 is filled in the preset gap g. The micro-ring cavity laser 21 and the waveguide 22 realize evanescent wave coupling through the preset gap g, and further realize directional laser output. The micro-ring cavity laser array solves the problems of low coupling efficiency and poor directivity of the conventional micro-ring cavity laser array, and simultaneously solves the problems of heat dissipation, beam shaping, multi-beam bundling, output coupling and the like of the conventional micro-ring cavity laser array.

Wherein, in the first direction, the length of the preset gap g may be 0.1-0.3 μm. The micro-ring cavity laser 21 and the waveguide 22 can be independently arranged through the preset gap g, the coupling efficiency is adjusted, evanescent wave coupling is achieved, the preset gap g is 0.1 mu m, and the coupling efficiency is the highest.

In an embodiment of the present invention, the waveguide 22 comprises an integrated input portion and output portion; in the same laser output unit 20, the input portion faces the micro ring cavity laser 21, the output portion faces away from the micro ring cavity laser 21, the width of the input portion gradually decreases in the first direction, and the width of the output portion remains unchanged in the first direction, which is directed to the waveguide 22 by the micro ring cavity laser 21.

It should be noted that the input portion is a tapered structure with gradually changing width, which facilitates beam shaping, multi-beam bundling and output coupling.

As shown in FIG. 2, the width w1 of the input portion of the waveguide 22 may be 1 to 2 μm, the width of the output portion w2 may be 0.3 to 0.5 μm, the length L of the waveguide 22 may be 20 to 30 μm, the thickness of the waveguide 22 is not less than the thickness of the active region 35 of the micro-ring cavity laser 21, the thickness of the waveguide 22 may be 0.4 to 0.7 μm, and the coupling distance between the micro-ring cavity laser 21 and the waveguide 22 may be 0.1 to 0.3 μm, at this time, both the quality factor and the light coupling output efficiency of the micro-ring cavity laser 21 reach optimal values.

Wherein the main lasing modes in each micro-ring cavity laser 21 are the radial propagation constant and the radiationFundamental transverse mode with minimum radiation loss and mode quality factor as high as 10⁵The magnitude and the side mode suppression ratio can reach 40 dB. The thickness of a material cladding of the micro-ring cavity laser 21 is 1-2 μm, and the requirement that the quality factor of the micro-ring cavity reaches the maximum value and the longitudinal optical mode is a fundamental mode is met. The etching depth of the micro-ring laser array is 3-4 mu m, and the requirements that the quality factor of the micro-ring resonant cavity reaches the maximum value and the optical modes in the resonant cavity are stably distributed are met.

As shown in fig. 3, in the second direction, the micro-ring cavity laser 21 includes a transition layer 31, an N-type ohmic contact layer 32, a lower confinement layer 33, a lower waveguide layer 34, the active region 35, an upper waveguide layer 36, an upper confinement layer 37 and a P-type ohmic contact layer 38, which are sequentially stacked on the first surface; wherein the second direction is directed from the first layer of silicon material 11 to the second layer of silicon material 13.

The transition layer 31 includes a nucleation layer 311, a buffer layer 312, and a dislocation blocking layer 315 sequentially arranged in the second direction, the dislocation blocking layer 315 includes a plurality of first periodic structures sequentially arranged in the second direction, the first periodic structures include a superlattice layer 313 and an isolation layer 314 sequentially arranged in the second direction, and the period may be set based on a requirement, for example, may be 4 periods.

A dislocation blocking layer 315 composed of a superlattice layer 313 is grown on the buffer layer 312, and the purpose is to effectively block dislocations generated due to lattice mismatch between the silicon substrate and the III-V semiconductor material, and prevent the dislocations from penetrating to the laser active region 35, so that the quality of the laser material is further optimized.

The active region 35 includes a plurality of second periodic structures sequentially arranged In the second direction, the second periodic structures including a quantum dot layer 354 and an isolation layer 355 sequentially arranged In the second direction, the quantum dot layer 354 including a first layer In sequentially arranged In the second direction_0.15Ga_0.85As351, InAs quantum dots 352 and second layer In_0.15Ga_0.85As353, the period can be set based on requirements, such As 5 periods.

Specifically, as shown in fig. 3: outside the selected region on the SOI 10Epitaxially growing a 15-25 nm GaAs nucleation layer 311, epitaxially growing a 1-2 μm GaAs buffer layer 312 on the GaAs nucleation layer 311, and growing 20nm In on the GaAs buffer layer 312_0.15Ga_0.85A dislocation barrier layer 315 consisting of an As/GaAs superlattice layer 313 and a 400nm GaAs isolation layer 314, a 200-300 nm N-type GaAs ohmic contact layer 32 is prepared above the dislocation barrier layer 315, and then 1-2 μm N-type Al is grown_0.4Ga_0.6An As lower limiting layer 33, a GaAs lower waveguide layer 34 with the thickness of 80-100 nm, an active region 35 and a GaAs upper waveguide layer 36 with the thickness of 35-75 nm are sequentially grown on the N-type lower limiting layer 33, and a P-type Al with the thickness of 1-2 mu m is grown on the GaAs upper waveguide layer 36_0.4Ga_0.6An As upper limiting layer 37, and finally a 200-300 nm P-type GaAs ohmic contact layer 38 is formed on the P-type upper limiting layer 37. Wherein the active region 35 comprises a first layer of In of 2nm_0.15Ga_0.85As351, 2.8ML InAs quantum dots 352, and 6nm second layer In_0.15Ga_0.85As353 and 45nm GaAs spacer 355.

According to the multi-wavelength silicon-based micro-ring laser array of the radial evanescent coupling conical silicon waveguide, the quality factor of the selected lasing mode in the micro-ring resonant cavity can be further optimized by selecting a proper laser epitaxial material structure and the structural parameters of the micro-ring cavity laser 21, such as the micro-ring radius, the micro-ring width, the etching depth and the like, so that the low-threshold lasing of the laser is realized; by selecting appropriate parameters of the tapered silicon waveguide, such as the width, thickness and taper length of the waveguide and the coupling distance between the tapered silicon waveguide and the micro-ring cavity, the light coupling output efficiency between the micro-ring resonant cavity and the silicon waveguide can be further optimized, and therefore directional light output with good unidirectionality is achieved.

That is, for the structural parameters of the micro-ring laser array structure, only one parameter is changed each time, the quality factor, the optical mode distribution and the light coupling output efficiency of the micro-ring cavity are changed accordingly, and the structural parameters when the three quantities reach the optimal values are the finally selected optimal micro-ring laser array structure. Meanwhile, by means of the radial coupling conical silicon waveguide structure, effective extraction of laser in the micro-ring cavity laser and low-loss and directional light transmission can be achieved. The method is favorable for realizing the multi-wavelength silicon-based integrated light source with high performance and low power consumption for large-scale dense wavelength division multiplexing application.

As can be seen from the above description, the multi-wavelength silicon-based micro-ring laser array for silicon-based optoelectronic monolithic integration provided by the technical solution of the present invention has the following advantages and beneficial effects:

1. by monolithically integrating a plurality of micro-ring cavity lasers with the same ring width and different inner and outer radiuses on the silicon on insulator, the lasing wavelength of each micro-ring cavity laser is in a 1.3 mu m wave band, and the wavelength interval is about 3 nm; and the radial evanescent coupling conical silicon waveguide at the edge of the microcavity can independently control the micro-ring cavity laser and the silicon waveguide structure, simultaneously improve the output optical power of the micro-ring laser array, and ensure that the micro-ring lasers are not influenced by each other.

2. Through the inhibition effect of the inner wall of the micro-ring on a high-order optical mode in the micro-cavity, the high-quality-factor fundamental transverse mode can realize single-mode lasing with a high side-mode inhibition ratio.

3. Because each micro-ring cavity laser forming the micro-ring laser array and the conical silicon waveguide radially coupled with the micro-ring cavity laser are all manufactured on the same silicon substrate, namely, each light emitting point in the micro-ring laser array is in the same plane, the light emitting points have the same light emitting direction and the emergent light is parallel to the structural plane, the structure of the micro-ring laser array is more compact, and the micro-ring laser array is beneficial to subsequent beam shaping, multi-beam bundling and light output coupling.

Compared with the existing semiconductor micro-cavity laser array, the invention belongs to a planar linear micro-cavity laser array, has good heat dissipation performance when devices are packaged, makes up the defects of structural design and optimization of the existing silicon-based monolithic integrated semiconductor micro-cavity laser array, and solves the problems of effective light extraction and light transmission of laser in the micro-cavity laser.

Based on the above embodiments, another embodiment of the present invention further provides a method for manufacturing a micro-ring laser array, as shown in fig. 4 to 25, and fig. 4 to 25 are process flow charts of the method for manufacturing the micro-ring laser array according to the embodiment of the present invention, where fig. 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 are top views, and fig. 5, 7, 9, 11, 13, 15, 17, 19, 21, and 25 are side views.

As shown in fig. 4 to 25, the manufacturing method includes:

step S11: as shown in fig. 4 and 5, a silicon-on-insulator 10 is provided, the silicon-on-insulator 10 including: a first layer of silicon material 11 and a second layer of silicon material 13 which are oppositely arranged, and a first silicon dioxide layer 12 which is positioned between the two layers of silicon materials;

step S12: as shown in fig. 6-9, the silicon-on-insulator 10 is patterned, the second layer of silicon material 13 is patterned into a plurality of waveguides 22, and a plurality of device regions with exposed first surfaces are formed on the first silicon dioxide layer 12; the first surface is a surface of the first layer of silicon material 11 facing the first silicon dioxide layer 12; the device regions do not overlap;

in the embodiment of the present invention, the method for patterning the silicon on insulator 10 includes:

firstly, cleaning the silicon-on-insulator 10; since the direct epitaxial growth process of semiconductor materials has high requirements on the cleanliness of the surface of the silicon-on-insulator 10, the silicon-on-insulator 10 is generally cleaned in the order of trichloroethylene-acetone-alcohol.

Then, as shown in fig. 6 and 7, etching the second layer of silicon material 13 until the first silicon dioxide layer 12 is exposed, so as to form a plurality of waveguides 22; the second layer of silicon material 13 on the upper layer of the silicon-on-insulator 10 can be etched by a dry etching technique such as ICP until the first silicon dioxide layer 12 is exposed, so as to prepare a mesa of a tapered silicon waveguide structure.

Finally, as shown in fig. 8 and 9, a portion of the first silicon dioxide layer 12 is removed by etching until the first silicon layer 11 is exposed, and a plurality of device regions are formed. After the tapered silicon waveguide 22 is etched, the first silicon dioxide layer 12 may be etched at a position where the laser structure is epitaxially grown on the selected region of the soi 10 until the first silicon layer 11 is exposed, where a distance between an etched boundary of the first silicon dioxide layer 12 and the waveguide 22 is 0.1-0.3 μm, which may be used as a coupling distance between the micro-ring cavity laser 21 and the waveguide 22.

Step S13: as shown in fig. 10 to 25, a plurality of micro ring cavity lasers 21 corresponding to the waveguides 22 one to one are formed in the first device region, and the micro ring cavity lasers 21 correspond to the device regions one to one;

wherein a plurality of laser output units 20 are arranged on the silicon-on-insulator 10; the laser output unit 20 includes: the micro-ring cavity laser 21 and the waveguide 22; the micro-ring cavity laser 21 is provided with an active area 35 for emitting laser light; the micro-ring cavity laser 21 has different sizes so as to emit laser with different wavelengths; in the first direction, the waveguide 22 is arranged opposite to the active region 35 of the corresponding micro-ring cavity laser 21; the first direction is the extending direction of the waveguide 22 and is parallel to the first silicon dioxide layer 12.

In the embodiment of the present invention, the method for forming the micro ring cavity laser 21 includes:

step S21: as shown in fig. 10 and 15, forming a mask layer 15 covering the waveguide 22, wherein the mask layer 15 exposes the device region;

first, as shown in FIG. 10 and FIG. 11, a photoresist layer 14 of 1-2 μm is coated on the exposed first silicon material layer 11.

Then, as shown in fig. 12 and 13, a silicon dioxide layer of about 350nm, that is, a mask layer 15, is deposited on the structure by a PECVD technique to protect the etched tapered silicon waveguide 22, and a gap between an edge of the mask layer 15 and the etched waveguide 22 is 0.1 to 0.3 μm, which can be used as a coupling gap between the micro-ring cavity laser 21 and the waveguide 22, thereby facilitating independent design of the micro-ring cavity laser 21 and the waveguide 22, effectively improving optical coupling efficiency between the micro-ring cavity laser 21 and the waveguide 22, and realizing evanescent wave coupling, wherein the gap is 0.1 μm, and coupling efficiency is the highest.

Finally, as shown in fig. 14 and 15, the masking layer 15 on the photoresist layer 14 is stripped with glue in the order of alcohol-acetone-trichloroethylene-stripper-trichloroethylene-acetone.

Step S22: as shown in fig. 16-17, an epitaxial layer 30 is formed in the device region, wherein the epitaxial layer 30 includes a transition layer 31, an N-type ohmic contact layer 32, a lower confinement layer 33, a lower waveguide layer 34, the active region 35, an upper waveguide layer 36, an upper confinement layer 37 and a P-type ohmic contact layer 38 sequentially formed on the first surface;

the selective epitaxial growth technique may be used to perform epitaxial growth of the micro ring cavity laser material structure In the etched laser pattern window, specifically, the transition layer 31 is sequentially epitaxially grown on the first silicon layer 11 (where the transition layer 31 includes a GaAs nucleation layer 311, a GaAs buffer layer 312, and a dislocation blocking layer 315, and the dislocation blocking layer 315 includes a GaAs isolation layer 314 and In_0.15Ga_0.85As/GaAs superlattice layer 313), N-type ohmic contact layer 32, lower confinement layer 33, lower waveguide layer 34, active region 35, upper waveguide layer 36, upper confinement layer 37, and P-type ohmic contact layer 38.

Preferably, the step S22 specifically includes:

firstly, carrying out region-selective epitaxial growth on a GaAs nucleating layer 311 with the thickness of 15-25 nm on a silicon-on-insulator 10, then epitaxially growing a GaAs buffer layer 312 with the thickness of 1-2 mu m on the GaAs nucleating layer 311, and then growing 20nm In on the GaAs buffer layer 312_0.15Ga_0.85Dislocation barrier layers 315(DFLs) consisting of As/GaAs superlattice layers 313(SLSs) and 400nm GaAs isolation layers 314, N-type GaAs ohmic contact layers 32 with the thickness of 200-300 nm are prepared above the dislocation barrier layers 315, and then N-type Al with the thickness of 1-2 mu m is grown_0.4Ga_0.6An As lower limiting layer 33, a GaAs lower waveguide layer 34 with the thickness of 80-100 nm, an active region 35 and an upper waveguide layer 36 with the thickness of 35-75 nm GaAs are sequentially grown on the N-type lower limiting layer 33, and a P-type Al with the thickness of 1-2 mu m is grown on the GaAs upper waveguide layer 36_0.4Ga_0.6An As upper limiting layer 37, and finally a 200-300 nm P-type GaAs ohmic contact layer 38 is formed on the P-type upper limiting layer 37. Wherein the active region 35 comprises a first layer of In of 2nm_0.15Ga_0.85As351, 2.8ML InAs quantum dots 352, and 6nm second layer In_0.15Ga_0.85As353 and 45nm GaAs spacer 355.

Specifically, dislocation barrier layers 315(DFLs) composed of superlattice layers 313(SLSs) are grown on the GaAs buffer layer 312, which are intended to effectively block dislocations generated due to lattice mismatch between the silicon substrate and the III-V semiconductor material, and prevent them from penetrating to the laser active region 35, so that the quality of the laser material is further optimized.

Specifically, In the DFLs structure, each SLS structure contains 5 periods of 10nm In_0.15Ga_0.85The As/10nm GaAs superlattice layer 313 is repeated for 4 times and is separated by a 300-400 nm GaAs isolation layer 314;

then, 200-300 nm of N-type GaAs ohmic contact layer 32 and 1-2 μm of N-type Al are sequentially epitaxially grown on the DFLs_0.4Ga_0.6An As lower limiting layer 33 and an 80-100 nm GaAs lower waveguide layer 34;

an active region 35 comprising 5 layers of undoped InAs/In is grown on the GaAs lower waveguide layer 34_0.15Ga_0.85An As/GaAs dot-In-well (DWELL) structure including a quantum dot layer 354 and a spacer layer 355 sequentially arranged In a second direction, the quantum dot layer 354 including a first layer In sequentially arranged In the second direction_0.15Ga_0.85As351, InAs quantum dots 352 and second layer In_0.15Ga_0.85As 353；

Specifically, In the DWELL structure with each layer, a 2nm first layer In is firstly epitaxially grown_0.15Ga_0.85As351, then 2.8ML InAs quantum dots 352, with a 6nm second layer of In As the uppermost layer_0.15Ga_0.85As353, which is used for achieving the purpose of prolonging the wavelength of the quantum dot laser; each DWELL structure is separated by a 35-45 nm GaAs isolation layer 355.

Growing 35-75 nm GaAs upper waveguide layer 36 and 1-2 mu m P type Al on the top layer of the active region 35_0.4Ga_0.6An As upper limiting layer 37;

and finally, growing a 200-300 nm thick P-type ohmic contact layer 38 on the top of the structure.

Step S23: as shown in fig. 18 and 19, the epitaxial layer 30 of the device region is etched to form a micro-ring resonator 40; etching until the N-type ohmic contact layer 32 is exposed, wherein the exposed part of the N-type ohmic contact layer 32 is arranged outside the micro-ring resonator 40;

the micro-ring resonant cavity 40 can be etched on the epitaxial layer 30 by utilizing the technologies of ICP dry etching, wet chemical etching and the like until the N-type ohmic contact layer 32 is exposed, the invention takes 4 micro-ring cavity lasers 21 as an example, wherein the widths of the micro-ring cavity lasers 21 are all 1.0 μm, the outer radiuses of the micro-ring cavity lasers 21 are 2.9 μm, 3.1 μm, 3.3 μm and 3.5 μm in sequence, and the intervals between the edges of the adjacent micro-ring cavity lasers 21 are all 0.5 μm.

Step S24: as shown in fig. 20 and fig. 21, forming a third silicon dioxide layer 16, wherein the third silicon dioxide layer 16 covers the micro-ring resonator 40 and the N-type ohmic contact layer 32;

the grown epitaxial layer 30 is cleaned in the order of acetone-trichloroethylene-alcohol, and then a layer of dense third silicon dioxide layer 16 with the thickness of about 350nm is deposited on the surface of the epitaxial layer 30 to serve as an insulating layer.

Step S25: as shown in fig. 22 to 25, a P-electrode 381 connected to the P-type ohmic contact layer 38 and an N-electrode 321 connected to the N-type ohmic contact layer 32 are formed.

The method of forming the P-electrode 381 is: on the structure where the third silicon dioxide layer 16 is deposited, a P-electrode window is manufactured by using a reverse photoresist lithography process and wet chemical etching, and a Ti-Pt-Au metal alloy material with a thickness of about 300nm is sputtered on the P-type ohmic contact layer 38 in the P-electrode window by using a magnetron sputtering technique to serve as a P-electrode material of the laser, so that the P-electrode 381 is prepared.

Specifically, the specific process for preparing the P electrode window is as follows:

and gluing the structure on which the third silicon dioxide layer 16 is deposited, exposing and developing by using a photoetching machine to form a photoresist mask, removing the third silicon dioxide layer 16 in the electrode window area by a wet chemical etching process to expose the P-type ohmic contact layer 38, and finally removing the photoresist to complete the P-electrode window.

The method for forming the N electrode 321 is: an N electrode window is manufactured by using a reverse photoresist photoetching process and wet chemical corrosion, and Au-Ge-Ni material with the thickness of about 300nm is sputtered on the N type ohmic contact layer 32 in the N electrode window by using a magnetron sputtering technology to be used as an N electrode material of a laser, so that the preparation of the N electrode 321 is completed.

Specifically, the specific process for preparing the N electrode window is as follows:

and gluing on the structure, exposing and developing by using a photoetching machine to form a photoresist mask, removing the third silicon dioxide layer 16 in the electrode window area by a wet chemical etching process to expose the N-type ohmic contact layer 32, and finally removing the photoresist to complete the N electrode 321 window.

FIG. 26 is a TE transverse electric mode in a micro-ring cavity laser obtained by numerical calculation using a three-dimensional time-domain finite (3D-FDTD) method_50，1The near field strength profile of (a). The outer radius of the micro-ring resonant cavity is 3.5 μm, the width of the micro-ring is 1.0 μm, the thicknesses of the upper and lower cladding layers of the laser material are both 1.5 μm, and the etching depth of the device is Al_0.4Ga_0.6The As lower confinement layer and the N-type GaAs ohmic contact layer. As shown in fig. 26, the optical modes in the micro-ring cavity laser are mainly distributed at the edge of the micro-cavity, while there is no mode distribution in the central region, and the perfect circularly symmetric distribution is presented in the horizontal direction, which indicates that the micro-ring laser structure has a very good limiting effect on the transverse mode optical field distribution in the micro-ring cavity.

FIG. 27 is a graph of the variation of lasing wavelength with microring radius at a fixed microring width of 1 μm calculated using the 3D-FDTD method. As can be seen from fig. 27, when the outer radius of the micro-ring is 2.7 μm, 2.9 μm, 3.1 μm, 3.3 μm, 3.5 μm, 3.7 μm and 3.9 μm, the main lasing wavelengths of the micro-ring lasers are 1291.29nm, 1294.51nm, 1298.14nm, 1301.42nm, 1304.53nm, 1307.21nm and 1309.48nm, and the mode Q factors are 93393, 94286, 78636, 158382, 160867, 124663 and 189065, respectively. Here in accordance with the size of the outer radius of the micro-ring cavity selected in step 22. It can be seen that a series of stable lasing wavelengths with a wavelength interval of about 3nm can be achieved by varying the inner and outer radii of the microrings at equal intervals while fixing the width of the microrings.

The change relation of the quality factor in the micro-ring cavity calculated based on the 3D-FDTD method along with the thickness of the Si waveguide is as follows, and the quality factors under different waveguide widths are all slowly reduced along with the increase of the thickness of the waveguide. Fig. 28 is a graph of the longitudinal mode optical field distribution in the Si waveguide at different waveguide thicknesses, and it can be seen that the optical mode in the Si waveguide has a tendency to transform from the fundamental mode to the multimode as the waveguide thickness increases, and it can be seen that the silicon waveguide can realize the fundamental mode transmission at the silicon waveguide thickness (0.435 μm) selected in step S12 of the specific embodiment.

The invention belongs to the technical field of micro-cavity lasers, and relates to a multi-wavelength silicon-based laser array based on radial evanescent coupling of a micro-ring resonant cavity and a conical silicon waveguide. Four micro-ring lasers with the same micro-ring width and micro-radius difference are integrated on the silicon-on-insulator 10 in parallel, stable lasing at a 1.3 mu m wave band can be realized by selecting proper structural parameters, equidistant lasing wavelength with a wavelength interval of about 3nm is realized by changing the radius of the micro-ring, and finally effective extraction and transmission of laser in the micro-ring lasers are realized by selecting proper structural parameters of the radial evanescent coupling conical Si waveguide.

Specifically, numerical calculation is carried out on the parameters such as the radius, the width of the micro-ring, the thickness of the cladding, the etching depth, the conical Si waveguide parameter, the coupling distance and the like of the micro-ring laser by adopting a 3D-FDTD method, and finally, when the radius of the micro-ring is 3.5 mu m, the width of the micro-ring is 1 mu m, the thickness of the cladding is 1.5 mu m, and the etching depth is Al_0.4Ga_0.6When the boundary between the As lower limit layer and the N-type GaAs ohmic contact layer is limited, the micro-ring laser can realize stable lasing. When the width of the micro-ring is fixed, the inner radius and the outer radius of the micro-ring are changed simultaneously, and the obtained lasing wavelength ranges from 1291.29nm to 1309.48nm, and the intervals are all about 3 nm. When the width of the input port of the conical Si waveguide is 1.0 μm, the length of the cone is 25 μm, the width of the output port is 0.3 μm, the thickness of the waveguide is 0.435 μm, and the coupling distance is 0.1 μm, unidirectional optical coupling output with the coupling efficiency of 23.5% can be realized without destroying the integrity of the micro-ring cavity. The result shows that the light output of the micro-ring cavity laser can be effectively realized through the radial evanescent coupling conical Si waveguide structure, and the micro-ring cavity laser array can be applied to a high-performance integrated light source in a dense wavelength division multiplexing system.

As can be seen from the above description, in the method for manufacturing a micro ring laser array according to the technical solution of the present invention, the micro ring laser array is a multi-wavelength silicon-based micro ring laser array monolithically integrated on a silicon-based optoelectronic chip, and a plurality of laser output units are manufactured on the same silicon on insulator, where the micro ring laser outputs laser light through a corresponding waveguide to realize directional laser output; and a plurality of laser output units are manufactured on the basis of the same silicon-on-insulator, and the first layer of silicon material is used as a silicon substrate and can be suitable for a silicon-based optical interconnection system; the laser output units are arranged on the same silicon-based substrate, the direct epitaxial growth process is simple, the silicon-based photonic devices can be conveniently stacked, packaged and manufactured in a large scale and at low cost, and the process can be compatible with the existing CMOS process.

The embodiments in the present description are described in a progressive manner, or in a parallel manner, or in a combination of a progressive manner and a parallel manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments can be referred to each other. For the manufacturing method disclosed by the embodiment, since the manufacturing method corresponds to the micro-ring laser array disclosed by the embodiment, the description is relatively simple, and the relevant points can be referred to the partial description of the micro-ring laser array.

It should be noted that in the description of the present application, it is to be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only used for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the present application. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in an article or device that comprises the element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A micro-ring laser array, comprising:

a silicon-on-insulator, the silicon-on-insulator comprising: the silicon-based composite material comprises a first layer of silicon material, a second layer of silicon material and a first silicon dioxide layer, wherein the first layer of silicon material and the second layer of silicon material are oppositely arranged, and the first silicon dioxide layer is positioned between the two layers of silicon materials;

a plurality of laser output units disposed on the silicon-on-insulator; the laser output unit includes: a micro-ring cavity laser and a waveguide; the micro-ring cavity laser is provided with an active area for emitting laser; the micro-ring cavity lasers have different sizes so as to emit laser with different wavelengths; in a first direction, the waveguide is arranged opposite to the active region of the corresponding micro-ring cavity laser; the first direction is the extending direction of the waveguide and is parallel to the first silicon dioxide layer;

the surface of the first layer of silicon material facing the first silicon dioxide layer is a first surface; the silicon-on-insulator has a plurality of device regions exposing the first surface; the device areas are not overlapped and are used for arranging the micro ring cavity lasers, and the micro ring cavity lasers correspond to the device areas one to one;

the second layer of silicon material includes a plurality of mutually independent waveguides.

2. The micro-ring laser array according to claim 1, wherein the geometric centers of the micro-ring cavity lasers are located on the same straight line;

the waveguides are located on the same side of the straight line, and the extending directions of the waveguides are parallel.

3. The micro-ring laser array according to claim 2, wherein the micro-ring lasers have micro-ring resonators with the same ring width and different outer diameters; and the edge distances of two adjacent micro-ring cavity lasers are the same.

4. The micro-ring laser array according to claim 1, wherein the laser output unit has a predetermined gap between the micro-ring cavity laser and the waveguide, and the predetermined gap is filled with a second silicon dioxide layer.

5. The micro-ring laser array according to claim 4, wherein the predetermined gap has a length of 0.1-0.3 μm in the first direction.

6. The micro-ring laser array of claim 1, wherein the waveguide comprises an integral input section and output section;

in the same laser output unit, the input part faces the micro ring cavity laser, the output part faces away from the micro ring cavity laser, the width of the input part is gradually reduced in the first direction, and the micro ring cavity laser points to the waveguide in the first direction.

7. The micro-ring laser array according to any one of claims 1-6, wherein in the second direction, the micro-ring laser comprises a transition layer, an N-type ohmic contact layer, a lower confinement layer, a lower waveguide layer, the active region, an upper waveguide layer, an upper confinement layer and a P-type ohmic contact layer, which are sequentially stacked on the first surface;

wherein the second direction is directed from the first layer of silicon material to the second layer of silicon material.

8. A method for manufacturing a micro-ring laser array is characterized by comprising the following steps:

providing a silicon-on-insulator, the silicon-on-insulator comprising: the silicon-based composite material comprises a first layer of silicon material, a second layer of silicon material and a first silicon dioxide layer, wherein the first layer of silicon material and the second layer of silicon material are oppositely arranged, and the first silicon dioxide layer is positioned between the two layers of silicon materials;

patterning the silicon-on-insulator, patterning the second layer of silicon material into a plurality of waveguides, and forming a plurality of device regions with exposed first surfaces on the first silicon dioxide layer; the first surface is a surface of the first layer of silicon material facing the first silicon dioxide layer; the device regions do not overlap;

forming a plurality of micro ring cavity lasers which are in one-to-one correspondence with the waveguides in the device area, wherein the micro ring cavity lasers are in one-to-one correspondence with the device area;

wherein a plurality of laser output units are arranged on the silicon-on-insulator; the laser output unit includes: the micro-ring cavity laser and the waveguide; the micro-ring cavity laser is provided with an active area for emitting laser; the micro-ring cavity lasers have different sizes so as to emit laser with different wavelengths; in a first direction, the waveguide is arranged opposite to the active region of the corresponding micro-ring cavity laser; the first direction is the extending direction of the waveguide and is parallel to the first silicon dioxide layer.

9. The method of claim 8, wherein the step of patterning the silicon-on-insulator comprises:

cleaning the silicon on insulator;

etching the second layer of silicon material until the first silicon dioxide layer is exposed to form a plurality of waveguides;

and etching and removing part of the first silicon oxide layer until the first silicon layer is exposed, and forming a plurality of device regions.

10. The method of fabricating of claim 8 wherein the method of forming the micro-ring cavity laser comprises:

forming a mask layer covering the waveguide, wherein the mask layer exposes the device area;

forming an epitaxial layer in the device region, wherein the epitaxial layer comprises a transition layer, an N-type ohmic contact layer, a lower limiting layer, a lower waveguide layer, the active region, an upper waveguide layer, an upper limiting layer and a P-type ohmic contact layer which are sequentially formed on the first surface;

etching the epitaxial layer of the device region to form a micro-ring resonant cavity; etching until the N-type ohmic contact layer is exposed, wherein the exposed part of the N-type ohmic contact layer is arranged outside the micro-ring resonant cavity;

forming a third silicon dioxide layer, wherein the third silicon dioxide layer covers the resonant cavity and the N-type ohmic contact layer;

and forming a P electrode connected with the P-type ohmic contact layer and an N electrode connected with the N-type ohmic contact layer.

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