CN212160140U

CN212160140U - Full-waveband polarizer based on silicon waveguide

Info

Publication number: CN212160140U
Application number: CN202020826535.5U
Authority: CN
Inventors: 时尧成; 刘卫喜
Original assignee: Zhejiang University ZJU; Sunny Optical Zhejiang Research Institute Co Ltd
Current assignee: Zhejiang University ZJU; Sunny Optical Zhejiang Research Institute Co Ltd
Priority date: 2020-05-18
Filing date: 2020-05-18
Publication date: 2020-12-15
Anticipated expiration: 2030-05-18

Abstract

The utility model discloses a full wave band polarizer based on silicon waveguide. The utility model consists of a shallow etching tapered gradual change silicon waveguide and a shallow etching strip silicon waveguide; the shallow-etching tapered gradual-change silicon waveguide comprises a first shallow-etching tapered gradual-change silicon waveguide and a second shallow-etching tapered gradual-change silicon waveguide; the shallow etching strip-shaped silicon waveguide is formed by a first shallow etching strip-shaped silicon waveguide; the input silicon waveguide is connected with a first shallow etching tapered silicon waveguide, and the first shallow etching strip-shaped silicon waveguide is respectively connected with the first shallow etching tapered silicon waveguide and a second shallow etching tapered silicon waveguide; the second shallow etched tapered silicon waveguide is connected with the output silicon waveguide. The utility model provides a full wave band polarizer of silicon waveguide has low-loss, high extinction ratio, big bandwidth, the simple characteristics of processing, satisfies the actual demand in fields such as optical communication, integrated optics.

Description

Full-waveband polarizer based on silicon waveguide

Technical Field

The utility model belongs to the optical communication field, concretely relates to full wave band polarizer based on silicon waveguide.

Background

With the rapid development of the fields of optical communication, optical sensing, optical imaging, etc., people have higher and higher demands for polarization control devices. The Polarization control device may be divided into a Polarizer (Polarizer), a Polarization Rotator (PR), and a Polarization Beam Splitter (PBS). The primary function of the polarizer is to lose the unwanted polarization and thus increase the fraction of the desired polarization. Conventional polarizers, including birefringent fibers, multilayer films, and the like, are typically large. The integrated photonic platform is represented by Silicon On Insulator (SOI), and strong limitation On an optical field is effectively realized by means of a Complementary Metal-Oxide-Semiconductor (CMOS) processing technology and the advantage of high refractive index of Silicon material, so that miniaturization of a device is promoted.

The current common polarizer based on the SOI platform mainly comprises a mixed surface plasma polarizer, a grating polarizer and a high birefringence silicon waveguide polarizer. Surface plasmon-based polarizers can achieve smaller size, higher polarization extinction ratio, however the inherent ohmic loss of metallic materials makes such polarizers more insertion loss. The grating polarizer effectively realizes polarization filtering by utilizing a photon forbidden band effect, can realize a polarizer with small size and high polarization extinction ratio, but has smaller bandwidth due to the wavelength sensitive characteristic of the grating structure. The birefringent silicon waveguide-based polarizer has the advantages of simple structure, high polarization extinction ratio, small insertion loss and the like, and is widely concerned. Common birefringence silicon waveguide polarizers include shallow etched silicon waveguide polarizers and adiabatic bending silicon waveguide polarizers. Although the traditional birefringence silicon waveguide polarizer can realize low insertion loss and high polarization extinction ratio, the polarizer with the structure has huge structural size and limited working bandwidth, and is difficult to meet the requirement of large bandwidth required by practical application.

Disclosure of Invention

An object of the utility model is to provide a full wave band polarizer based on silicon waveguide utilizes the toper gradual change silicon waveguide of shallow sculpture and the bar silicon waveguide of shallow sculpture to realize covering full optical communication wave band high polarization extinction ratio, low-loss polarizer.

The utility model provides a full wave band polarizer based on silicon waveguide comprises shallow etching toper gradual change silicon waveguide and shallow etching bar silicon waveguide. The shallow-etching tapered gradual-change silicon waveguide comprises a first shallow-etching tapered gradual-change silicon waveguide (2) and a second shallow-etching tapered gradual-change silicon waveguide (4); the shallow etching strip-shaped silicon waveguide is formed by a first shallow etching strip-shaped silicon waveguide (3); the input silicon waveguide (1) is connected with a first shallow etching tapered silicon waveguide (2), and the first shallow etching strip-shaped silicon waveguide (3) is respectively connected with the first shallow etching tapered silicon waveguide (2) and a second shallow etching tapered silicon waveguide (4). The second shallow etched tapered silicon waveguide is connected with an output silicon waveguide (5).

The shallow etching conical gradual change silicon waveguide and the shallow etching strip-shaped silicon waveguide have the same etching depth.

The utility model discloses well optical signal is by input silicon waveguide 1 input, through first shallow etching toper gradual change silicon waveguide 2, and the polarized light (TM) of the perpendicular silicon waveguide upper surface direction of electric field takes place the part and reveals to reveal to the substrate silicon layer from the silica substrate, another polarized light (TE) realizes from thick silicon waveguide to the low conversion that loses of shallow etching silicon waveguide. The light energy after the primary filtering enters the first shallow etching strip-shaped silicon waveguide 3, TM polarized light is further lost, and TE polarized light realizes lossless transmission. The light filtered by the first shallow etching strip-shaped silicon waveguide 3 enters the second shallow etching tapered gradual-change silicon waveguide 4, TM polarized light is lost, TE polarized light realizes low-loss conversion from the shallow etching strip-shaped silicon waveguide to the thick silicon waveguide and is output from the output silicon waveguide 5, and therefore the full-wave-band polarization effect is achieved.

Preferably, the first shallow etching tapered gradual change silicon waveguide inputs 1260-1675 nm of optical signals into the first shallow etching strip-shaped silicon waveguide and outputs the optical signals by the second shallow etching tapered gradual change silicon waveguide.

Preferably, the input end of the polarizer is provided with an input silicon waveguide (1), and the output end is provided with an output silicon waveguide (5).

Preferably, the input silicon waveguide (1) and the output silicon waveguide (5) are both deep-etched silicon strip waveguides.

Preferably, the thickness of the substrate is 700 μm, the thickness of the buried layer is 2 μm, the thickness of the silicon core layer is 220nm, and the etching depth of the shallow etching is 120 nm.

Preferably, the polarizer structure is centrosymmetric with respect to the central shallow etched strip silicon waveguide.

The utility model discloses the profitable effect that has is:

(1) the shallow etched tapered gradual-change silicon waveguide can realize the high-efficiency conversion of TE light in the silicon waveguides with different thicknesses in the whole communication waveband, so that the insertion loss of the whole polarizer is reduced, and the working bandwidth (O, E, S, C, L, U, 1260nm-1675nm) covering the whole communication waveband is realized.

(2) TM polarized light can be efficiently lost by using the shallow etching strip-shaped silicon waveguide, so that high polarization extinction ratio is obtained.

(3) The tapered gradual change silicon waveguide and the shallow etching strip silicon waveguide with the same etching depth are adopted, so that the process steps are reduced, and the processing cost of the device is reduced.

Drawings

FIG. 1 is a schematic top view of a full-band polarizer structure of a silicon waveguide according to the present invention;

in the figure: 1. the waveguide structure comprises an input silicon waveguide, 2 a first shallow etching tapered silicon waveguide, 3 a first shallow etching strip-shaped silicon waveguide, 4 a second shallow etching tapered silicon waveguide and 5 an output silicon waveguide.

FIG. 2 is a simplified diagram of the process for preparing the full-band polarizer of the silicon waveguide of the present invention;

FIG. 3 is a cross-sectional view of the input waveguide (output waveguide) in the full-band polarizer of the silicon waveguide of the present invention;

FIG. 4 is a cross-sectional view of a shallow etched tapered graded silicon waveguide structure in a full-band polarizer of the silicon waveguide of the present invention;

FIG. 5 is a cross-sectional view of a shallow etched strip-shaped silicon waveguide structure in a full-band polarizer of the silicon waveguide of the present invention;

FIG. 6 outputs TE polarization and TM polarization transmittance simulation curves for a silicon waveguide.

In order to more clearly show the difference between the deep-etched silicon waveguide and the shallow-etched silicon waveguide, the deep-etched silicon core layer and the shallow-etched silicon layer are shown as 220nm thick silicon and 100nm thick silicon in fig. 1, and air in the upper cladding layer is not shown.

Detailed Description

The present invention will be further explained with reference to the accompanying drawings and examples of embodiments of full-band polarizers based on silicon waveguides.

In order to better explain the present embodiment, the components of the drawings are enlarged or reduced and omitted, and do not represent actual product sizes.

As shown in fig. 1, 3, 4 and 5, the structure of the silicon waveguide full-band polarizer of the embodiment is schematically shown.

The silicon waveguide polarizer of the embodiment comprises a silicon substrate 7, a buried layer 8, a silicon core layer 9 and an upper cladding layer 10 which are arranged from bottom to top.

Selecting a nanowire silicon waveguide based on an SOI material, wherein a silicon core layer is made of a silicon material, the thickness of the silicon core layer is 220nm, and the refractive index of the silicon core layer is 3.476; the buried layer is a 2-micron silicon dioxide insulating layer with the refractive index of 1.445; the substrate layer is a 700 mu m silicon substrate, and the refractive index of the substrate layer is the same as that of the silicon core layer; the upper cladding is air and has a refractive index of 1. All the silicon waveguides are uniform in width and 500nm, the tip of the shallow-etched tapered silicon waveguide is 60nm, the etching depth of the shallow etching is 120nm, and the silicon waveguide transmits a TE and TM mixed polarization fundamental mode.

The two shallow-etched tapered silicon waveguides are uniformly and linearly tapered and symmetrical, the width change is from 500nm to 60nm, the tapered length is 10 mu m, and the length of the middle shallow-etched strip-shaped silicon waveguide is 50 mu m.

The TE polarization and TM polarization transmittance simulation curves of the output silicon waveguide are shown in FIG. 6. TM polarized light can be efficiently lost by using the shallow etching strip-shaped silicon waveguide, so that high polarization extinction ratio is obtained.

The above-mentioned embodiments are provided for explaining the present invention, not for limiting the present invention, and any modifications and changes made to the present invention are within the spirit of the present invention and the scope of the claims and fall within the scope of the present invention.

Claims

1. The full-waveband polarizer based on the silicon waveguide is characterized by consisting of a shallow-etched tapered gradual-change silicon waveguide and a shallow-etched strip-shaped silicon waveguide; the shallow-etching tapered gradual-change silicon waveguide comprises a first shallow-etching tapered gradual-change silicon waveguide (2) and a second shallow-etching tapered gradual-change silicon waveguide (4); the shallow etching strip-shaped silicon waveguide is formed by a first shallow etching strip-shaped silicon waveguide (3); the input silicon waveguide (1) is connected with a first shallow etching tapered silicon waveguide (2), and the first shallow etching strip-shaped silicon waveguide (3) is respectively connected with the first shallow etching tapered silicon waveguide (2) and a second shallow etching tapered silicon waveguide (4); the second shallow etched tapered silicon waveguide is connected with an output silicon waveguide (5).

2. The full-band silicon waveguide-based polarizer according to claim 1, wherein the first shallow etched tapered silicon waveguide (2) is connected to the first shallow etched silicon waveguide (3) at the tapered tip of the first shallow etched tapered silicon waveguide (2), and the first shallow etched silicon waveguide (3) is connected to the second shallow etched tapered silicon waveguide (4) at the tapered tip of the second shallow etched tapered silicon waveguide (4).

3. The full-band silicon waveguide-based polarizer according to claim 1 or 2, wherein the shallow etched tapered graded silicon waveguide and the shallow etched strip silicon waveguide have the same etching depth.

4. A full-band polarizer based on silicon waveguides as claimed in claim 3, characterised in that the polarizer is provided with an input silicon waveguide (1) at the input and an output silicon waveguide (5) at the output.

5. The full-band silicon waveguide-based polarizer according to claim 3, wherein the polarizer is implemented as follows:

an optical signal is input from an input silicon waveguide (1), and passes through a first shallow etching tapered gradual change silicon waveguide (2), polarized light (TM) with an electric field vertical to the upper surface direction of the silicon waveguide partially leaks and leaks to a substrate silicon layer from a silicon dioxide substrate, and low-loss conversion from a thick silicon waveguide to the silicon waveguide is realized by the other polarized light (TE); the light energy after primary filtering enters a first shallow etching strip-shaped silicon waveguide (3), the polarized light (TM) is further lost, and the other polarized light (TE) realizes lossless transmission; light filtered by the first shallow etching strip-shaped silicon waveguide (3) enters the second shallow etching tapered gradual-change silicon waveguide (4), the loss of polarized light (TM) is almost lost, and the other polarized light (TE) realizes low-loss conversion from the shallow etching strip-shaped silicon waveguide to the thick silicon waveguide and is output from the output silicon waveguide (5), so that the full-band polarization effect is realized.

6. The full-band polarizer based on silicon waveguides as claimed in claim 4 or 5, characterised in that the input (1) and output (5) silicon waveguides are deep etched silicon strip waveguides.

7. The full-band polarizer based on silicon waveguide as claimed in claim 6, wherein the substrate has a thickness of 700 μm, the buried layer has a thickness of 2 μm, the silicon core layer has a thickness of 220nm, and the shallow etching depth is 120 nm; all silicon waveguides are uniform in width and 500nm, and the tips of the shallow-etched tapered silicon waveguides are 60 nm.

8. The full-band silicon waveguide-based polarizer according to claim 6, wherein the polarizer structure is centrosymmetric with respect to the central shallow etched strip-shaped silicon waveguide.

9. The full-band polarizer based on silicon waveguides as claimed in claim 7 or 8, wherein the two shallow etched tapered silicon waveguides are uniformly linearly tapered and symmetrical, the width variation is from 500nm to 60nm, the tapered length is 10 μm, and the middle shallow etched strip silicon waveguide length is 50 μm.