CN114153032B - Three-dimensional asymmetric microcavity device for light field regulation and integration device thereof - Google Patents
Three-dimensional asymmetric microcavity device for light field regulation and integration device thereof Download PDFInfo
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Abstract
The invention provides a three-dimensional asymmetric microcavity device for light field regulation and control and an integrated device thereof, wherein the three-dimensional asymmetric microcavity device comprises a substrate and an optical micro-ring cavity positioned on the substrate, the section of the optical micro-ring cavity gradually deflects according to a section deflection angle theta along with the change of an azimuth angle phi of a micro-ring, and a closed loop connected end to end is formed; the cross section of the optical micro-ring cavity is a cross section passing through the ring center along the axial direction of the micro-ring cavity, and the cross section deflection angle theta is an included angle between the midpoint connecting line direction of the short sides of the cross section and the axial direction perpendicular to the substrate. The technical scheme of the invention adopts a three-dimensional asymmetric structure, supports the light field to form resonance in the whispering gallery mode, can be used as a passive or active integrated device, realizes the regulation and control of polarization, spin and wavelength by utilizing the spin orbit coupling phenomenon in the light field, does not need to depend on special materials, and is suitable for an extremely wide band range; the laser beam can be conveniently manufactured through single femtosecond laser processing, and has the advantages of compact design, convenience in integration and multiplexing.
Description
Technical Field
The invention belongs to the fields of light transmission, light signal generation and processing technology and on-chip photon devices, and particularly relates to a three-dimensional asymmetric microcavity device for light field regulation and control and an integrated device thereof.
Background
Polarization is one of the fundamental properties of light. Conventional elements for manipulating the polarization of light, the spin properties of light, are transparent wave plates with specific birefringence properties, such as half wave plates, quarter wave plates, etc. With the progress of leading edge science in recent years, a novel half-wave plate with a periodically gradual structure in a polar coordinate system, namely a q-plate (q-plate), is developed, and can generate and regulate the orbital angular momentum of light. The same type of novel devices for regulating and controlling the polarization and the spin of the light field comprise a liquid crystal variable wave plate, a Dammann grating and the like. The elements are used for regulating and controlling the light beam in free space, and have important significance in the application of the optical communication field of large bandwidth and all-optical exchange, in particular in the optical information systems of polarization multiplexing and mode division multiplexing. However, waveplates are bulky, difficult to integrate, require precise optical alignment during operation, and have significant wavelength selectivity and limitations. In recent years, academic research on super-structured surfaces has promoted the application of sub-wavelength scale planar structures in the aspects of generating geometric phases and optical field regulation. The device has compact size and high performance, is suitable for regulating and controlling a free space optical path, but has huge mode field mismatch compared with a traditional optical waveguide device integrated on a chip and having submicron scale, and needs a special coupling strategy, so that the integration is difficult to realize.
The existing on-chip integrated polarization regulation device is mainly based on propagation difference characteristics of different polarization modes in the waveguide, and can form a polarization beam splitter and a polarization converter. However, such devices are mainly based on cascaded waveguides, and require a certain propagation distance to realize mode discrimination, and have large occupied size, which is unfavorable for high-density integration. In addition, the design realizes single functions, such as separation of two polarization modes or conversion between two specific polarizations, and main performance parameters, such as extinction ratio, insertion loss and application bandwidth, are limited due to the actual processing technology.
An optical microcavity with whispering gallery modes is a widely used structure in integrated photonic circuits. Because the light source has high quality factor and compact volume, the light source can be used for realizing the functions of light source, light amplification, signal modulation, light field sensing and the like, and particularly, the performance of the light source is greatly improved by the effect of cavity field enhancement. The traditional whispering gallery mode on-chip devices represented by micro-rings and micro-discs are plane devices, and adopt symmetrical design, and the working condition is usually a single polarization mode, namely one of transverse electric and transverse magnetic orthogonal modes. However, the device itself lacks the processing capability for complex and mixed polarization, and the regulation and control can be realized by additionally integrating magnetic poles or preparing microcavities based on magneto-optical materials and introducing an external magnetic field.
Disclosure of Invention
Aiming at the technical problems, the invention discloses a three-dimensional asymmetric microcavity device for light field regulation and control and an integrated device thereof, wherein the device can realize free regulation and control on polarization, spin, wavelength and other characteristics of a light field and a motion track, can be integrated with conventional optical waveguide devices such as an on-chip optical waveguide, an optical fiber and the like, can be applied to realizing functions required in various integrated photon chips, such as a filter, a polarization converter, a multiplexer, a light source, an amplifier, a polarization meter and the like, and can also be applied to the fields of special optical sensing, optical calculation, quantum communication and the like. The integrated device can be a passive on-chip device, a multiplexing device, an active three-dimensional microcavity device and the like containing three-dimensional asymmetric microcavities for light field regulation.
In this regard, the invention adopts the following technical scheme:
the three-dimensional asymmetric microcavity device for light field regulation comprises a substrate and an optical micro-ring cavity positioned on the substrate, wherein the optical micro-ring cavity is of an echo wall structure, the section of the optical micro-ring cavity gradually deflects along with the change of azimuth angle phi of a micro-ring according to section deflection angle theta, and a closed loop connected end to end is formed; the cross section of the optical micro-ring cavity is a cross section passing through the ring center along the axial direction of the optical micro-ring cavity, the cross section deflection angle theta is an included angle between the connecting line direction of the midpoint of the short side of the cross section and the axial direction of the substrate, and the azimuth angle phi satisfies the following conditions: phi is more than or equal to 0 DEG and less than or equal to 360 deg.
The technical scheme provides a novel three-dimensional asymmetric microcavity device structure, wherein a cross section gradually changing along with an azimuth angle is introduced on the basis of a plane micro-ring formed by an optical waveguide with a rectangular cross section, and the end-to-end positions are overlapped to form a closed loop. The precise regulation and control of the structural gradient on the guided wave condition is utilized to change the motion track of the resonant photon and the relative orbital angular momentum and spin angular momentum characteristics thereof, and the mutual coupling strength is regulated and controlled. Compared with a conventional annular whispering gallery mode microcavity on a chip, the structure can additionally realize the following new functions: 1) Free regulation and conversion of the polarization state of the input light wave; 2) As a filter device for discriminating the spin state of the input light wave; 3) As a light source, light field regulation and control with different polarization states of multipath output are realized.
As a further development of the invention, the cross section is rectangular.
As a further improvement of the present invention, the section deflection angle θ satisfies: and the section deflection angle theta is larger than or equal to 0 degree and smaller than or equal to 90 degrees, and is changed along with the azimuth angle phi from 0 degree, and reaches the maximum value of 90 degrees after the azimuth angle phi is changed by 180 degrees. I.e. the cross-section after 180 degrees of change completely evolves into the horizontal direction, the deflection angle reaches a maximum of 90.
By adopting the technical scheme, the symmetry is broken on the basis of the traditional planar micro-ring, a spin orbit coupling mechanism is introduced, and the spin angular momentum is equivalently modulated by changing the direction of the cross section at different azimuth angles, so that the polarization of light can deflect along the deflection of the cross section although the light field motion track is still in the x-y plane.
As a further improvement of the invention, the long side of the rectangle is 2-20 micrometers, and the short side is 400 nanometers-2 micrometers.
As a further improvement of the invention, the cross section is quadrilateral, and the heights of the tops of the cross sections at all positions of the optical micro-ring cavity from the base are equal.
As a further improvement of the invention, the optical micro-ring cavity is in a frustum shape with a big top and a small bottom or with a big top and a big bottom.
As a further improvement of the present invention, the section deflection angle θ satisfies: θ 1 ≤θ≤θ 2 Wherein θ 1 、θ 2 Ranging from 1 ° to 20 °.
By adopting the technical scheme, the polarization-state free conversion device has higher structural freedom degree, and can be used for realizing free regulation and control of polarization states, including free conversion, identification, separation and generation of linear polarization, circular polarization, elliptical polarization and left-handed and right-handed spin polarization states.
As a further improvement of the invention, the height W of the top of the section from the base is 2-20 micrometers, and the lengths of the upper bottom T1 and the lower bottom T2 of the section meet 400-2 micrometers.
By adopting the technical scheme, besides introducing deflection angles, the structure has a non-uniform width design of the cross section, and the equivalent refractive index distribution n of the mode along the axial z-axis direction of the substrate eff (z) modulation is obtained, and the optical wave transmission track can be realized to be inclined by original mediocre in-plane resonance according to the Fermat principleOut-of-plane resonance trajectories.
As a further improvement of the present invention, the diameter of the optical micro-ring cavity is 3-1000 microns.
The invention also discloses a preparation method of the three-dimensional asymmetric microcavity device for light field regulation, wherein the optical micro-ring cavity is formed on a substrate by adopting a two-photon polymerization or ablation 3D printing technology. Further, a 3D printing technique of two-photon polymerization or ablation based on femtosecond laser scanning is adopted.
The invention also discloses a passive on-chip device which is an integrated device based on the three-dimensional asymmetric microcavity for light field regulation, and comprises the three-dimensional asymmetric microcavity device for light field regulation and a planar waveguide or an optical fiber, wherein the planar waveguide or the optical fiber is positioned on one side of the three-dimensional asymmetric microcavity device for light field regulation for coupling. Preferably, the planar waveguide is a channel waveguide with a rectangular cross section. Further preferably, the planar waveguide is a single-mode waveguide. The planar waveguide is made of silicon, silicon nitride, silicon dioxide, indium phosphide or polymer.
As a further improvement of the invention, the passive on-chip device is a passive on-chip filter device, the passive on-chip filter device comprises a bottom cladding with a low refractive index, a groove is arranged on the bottom cladding, the three-dimensional asymmetric microcavity device for light field regulation is connected with the bottom of the groove through a support column, and the planar waveguide is positioned on the surface of the bottom cladding and outside the three-dimensional asymmetric microcavity device for light field regulation. And a gap is reserved between the planar waveguide and the three-dimensional asymmetric microcavity device for optical field regulation.
The invention also discloses a multiplexing device which is an integrated device based on the three-dimensional asymmetric microcavity for light field regulation, and comprises the three-dimensional asymmetric microcavity device for light field regulation and a plurality of waveguides, wherein the waveguides form a waveguide array, the waveguides are in contact with the side wall of the three-dimensional asymmetric microcavity device for light field regulation, and the extending directions of the waveguides are parallel to the substrate of the three-dimensional asymmetric microcavity device for light field regulation.
The invention also discloses an active three-dimensional microcavity device which is an integrated device based on the three-dimensional asymmetric microcavity for light field regulation, and comprises the three-dimensional asymmetric microcavity device for light field regulation, wherein an optical micro-ring cavity of the three-dimensional asymmetric microcavity device for light field regulation contains active materials.
As a further improvement of the present invention, the active material includes at least one of a fluorescent dye, an up-conversion material, an aggregation-induced emission molecule, colloidal quantum dots, or an optical material having strong nonlinear characteristics. By adopting the technical scheme, active materials are introduced, and resonance signals can be formed by pumping with an external light source and photoluminescence. The output light may be collected by a waveguide or an optical fiber. The device can be used as a multimode lasing light source to realize specific spin orbit coupling in different mode resonance orbits, so that different polarization properties are carried among modes, the device can be used for free space optical communication, on-chip optical communication optical interconnection, optical calculation, optical sensing and other applications, and can also be used as a quantum light source to generate polarization entangled photons for processing single photon characteristics and be used for quantum communication and quantum calculation.
Compared with the prior art, the invention has the beneficial effects that:
aiming at the common limitations of large volume, difficult integration, limited applicable bandwidth, single function and the like in the prior art, the technical scheme of the invention is improved, and has the beneficial effects that the method mainly comprises the following three aspects:
(1) The technical scheme of the invention adopts a three-dimensional asymmetric structure, supports the light field to form resonance in the whispering gallery mode, can be used as a passive or active device, can utilize the spin orbit coupling phenomenon in the light field to realize the regulation and control of polarization, spin and wavelength, does not need to depend on special materials, and is suitable for an extremely wide band range. Compared with the traditional wave plate, the structure of the wave plate can be conveniently and fast manufactured through single femtosecond laser processing, and the wave plate has the natural advantage of compact design as a miniature optical cavity, and solves the problems of large volume, difficult integration, limited applicable bandwidth and single function.
(2) The technical scheme of the invention can be established on the basis of a conventional on-chip IV-III-V semiconductor optical waveguide loop for preparation, so that a complete heterogeneous integration flow is formed. At the same time, its compact microcavity structure is highly compatible with fully automated, flow-through optical waveguide, fiber coupling technologies already in the industry.
(3) Due to the adoption of a three-dimensional asymmetric structure, the technical scheme of the invention can axially accommodate a theoretical upper-limit-free high-order resonance mode to acquire spin orbit coupling and geometric phases with different intensities, so that multiplexing polarization regulation and control can be realized by adopting a single device. The regulated light field can be transmitted on a chip, can be coupled to a free space through a lens, and has wide practicability.
Drawings
Fig. 1 is a schematic structural diagram of a three-dimensional asymmetric microcavity device for light field modulation according to embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view of three of the sites A, X, B of FIG. 1; wherein (a) is point A, (B) is point X, and (c) is point B.
Fig. 3 is a correspondence relationship between azimuth and deflection angle in embodiment 1 of the present invention.
Fig. 4 is a schematic diagram of the light field polarization state evolution of the microcavity structure of embodiment 1 of the present invention in the poincare sphere.
FIG. 5 is a three-dimensional light field simulation result diagram of embodiment 1 of the present invention; wherein (a) is a resonance spectrogram; (b) Is a top view of the light field intensity, comprising two partial magnified views.
Fig. 6 is a schematic structural diagram of a three-dimensional asymmetric microcavity device for optical field modulation according to embodiment 2 of the present invention, wherein (a) is a perspective view and (b) is an oblique optical wave resonance trace diagram.
Fig. 7 is a cross-sectional view of three of the sites A, X, B of fig. 6; wherein (a) is point A, (B) is point X, and (c) is point B.
Fig. 8 is a graph showing the relationship between azimuth angle and inclination angle in embodiment 2 of the present invention.
Fig. 9 is a schematic diagram of the evolution of the optical field polarization state in poincare sphere of the microcavity device according to embodiment 1 of the present invention, wherein (a) is a left-handed case and (b) is a right-handed case.
FIG. 10 is a plot of the corresponding azimuth angles and the corresponding resonant wavelengths of the Poincare sphere for different ellipsoids according to embodiment 2 of the present invention; wherein (a) is a schematic diagram of azimuth angles corresponding to different ellipsoids in the poincare sphere, and (b) is a diagram of the correspondence between azimuth angles and resonant wavelengths.
FIG. 11 is a three-dimensional light field simulation result of embodiment 2 of the present invention; wherein (a) is a resonance spectrogram, (b) is a side view of light field intensity distribution, and (c) is a polarization resolution polar graph acquired at different positions of the z-axis.
Fig. 12 is a schematic diagram of the processing of the device of example 1 prepared by two-photon polymerization in example 3 of the present invention.
Fig. 13 is an electron scanning microscope image of the device of example 1 prepared in example 3 of the present invention.
Fig. 14 is a schematic structural diagram of the microcavity device of embodiment 4 of the present invention applied to a passive device; wherein (a) is a schematic side view of coupling using tapered fibers and (b) is an optical microscope image.
Fig. 15 is a schematic structural diagram of a characterization system for output light in a passive structure in embodiment 4 of the present invention.
FIG. 16 is a graph of characterization measurements of the passive device of example 4 of the present invention; wherein (a) is a transmission spectrum and (b) is a polarization-resolved polar graph obtained at A, B two measurement positions.
Fig. 17 is a schematic structural diagram of a passive on-chip filter device according to embodiment 5 of the present invention; wherein, (a) is a side view, (b) is a top view of the dual waveguides when coupled at A, B points, respectively, and (c) is a top view of the coupled waveguides with respect to the polarization state output when coupled at any azimuth angle.
Fig. 18 is a schematic diagram showing the structure of an on-chip multiplexed waveguide coupling device according to embodiment 6 of the present invention; wherein, (a) is a side view and (b) is a top view.
Fig. 19 is a three-dimensional light field simulation result diagram of an active microcavity device according to embodiment 6 of the present invention for coupling out signals from different axial positions, wherein (a) is right-handed elliptical polarization and (b) is left-handed elliptical polarization.
Fig. 20 is a schematic diagram of a pump light spatially selective excitation and signal collection device for an active microcavity device according to embodiment 6 of the present invention.
Wherein the reference numerals include: 101-high energy density light beam, 102-effective focus, 103-three-dimensional microcavity structure, 104-substrate, 105-photoresist;
201-tapered fiber, 202-microcavity cavity, 203-pillar, 204-channel waveguide, 205-bottom cladding, 206-outcoupling waveguide;
301-wavelength tunable laser, 302-polarization control module, 303-coupling module, 304-photodetector or spectrometer, 305-polarization analyzer module or polarimeter, 306-objective lens, 307-imaging camera;
401-microcavity, 402-waveguide array;
501-pumping light source, 502-spatial light modulator, 503-objective lens, 504-active microcavity device, 505-electric control displacement platform, 506-array coupling system, 507-filter.
Detailed Description
Preferred embodiments of the present invention are described in further detail below.
Example 1
As shown in fig. 1 to 3, a three-dimensional asymmetric microcavity device for light field regulation comprises a substrate and an optical micro-ring cavity positioned on the substrate, wherein the optical micro-ring cavity supports an optical whispering gallery resonance mode, the section of the optical micro-ring cavity is gradually deflected along with the change of azimuth angle phi of a micro-ring according to a section deflection angle theta, and a closed loop connected end to end is formed. Wherein the cross section of the micro-ring cavity is rectangular. Fig. 1 is a perspective view in which the optical wave resonance locus is identified.
The axial direction perpendicular to the chip substrate is defined as the z-axis. The cross section of the optical micro-ring cavity is a cross section passing through the ring center along the axial direction of the optical micro-ring cavity, and the cross section deflection angle theta is defined as an included angle between the connecting line direction of the midpoint of the short side of the cross section and the axial direction of the substrate, namely an included angle between the rectangular long side of the cross section and the z axis. In fig. 3, the deflection angle at point a is 0 degrees, where the rectangular long side of the cross section (length is defined as W) is parallel to the z-axis, and after the azimuth angle Φ becomes large, the cross section starts to deflect (as shown by point X), and after the angle Φ changes by 180 degrees (point B), the cross section completely evolves into the horizontal direction, and the deflection angle reaches the maximum, which is 90 degrees. The section then evolves again through the azimuth angle in the interval of 180-360 degrees, and finally the closed loop of end to end is realized. Fig. 3 shows the relationship between deflection angle and azimuth angle.
The light carries a certain spin angular momentum, direction and sign when propagating along the waveguide and is related to the spin component of the light wave and is coplanar with the propagation track, so that the light wave has effective orbital angular momentum when resonating along the closed loop of the micro-ring. However, in conventional planar micro-rings, the coupling between spin angular momentum and orbital angular momentum is very weak and negligible. By adopting the structure of the technical scheme of the embodiment, the spin angular momentum is equivalently modulated by changing the direction of the section at different azimuth angles. Thus, although the light field motion profile is still in the x-y plane, the polarization of the light may be deflected along the deflection of the cross-section.
The trajectory of the polarization state of the transmitted light on the poincare sphere is shown in fig. 4. If the point a is defined as one of two orthogonal linear polarization modes, namely, the transverse magnetic mode TM in the conventional on-chip waveguide, the light is propagated after 180 degrees of azimuth angle, the same mode evolves into the light with the linear polarization mode along the horizontal direction at the point B, namely, the transverse electric mode TE in the conventional on-chip waveguide, and the corresponding evolution track is located at the equatorial position in the poincare sphere. When the point A is horizontal linear polarization mode light, the evolution effect is the same. Therefore, the corresponding linear polarization state with a certain angle can be obtained through coupling output in different azimuth angles, and the polarization deflection and the section polarization have clear corresponding relations.
Fig. 5 shows a simulation result of a specific example of the structure using the three-dimensional electromagnetic field simulation module in the finite element calculation tool COMSOL Multiphysics. Wherein the emulation wavelength is near the C-band of communication (about 1530-1565 nm). Fig. 5 (a) shows the periodic resonance spectrum in this structure, with adjacent modes having different azimuthal mode numbers, and the mode spacing (i.e., the "free spectral range") exhibiting equidistant effects. Each set of modes includes two sets of orthogonal polarization components. Fig. 5 (b) shows a top view of the light field intensity distribution at a selected specific mode wavelength. The 90 degree deflection effect of the structure on the polarization direction of the propagating light can be clearly seen from the partial enlarged diagrams at the point A and the point B and the polarization direction of the light field marked by the arrow.
Furthermore, the structure of the embodiment can be widely applied to different wave bands such as visible light, near infrared, middle infrared and the like. A unified adjustment can be made for all design parameters corresponding to the band. The following design takes the communication C-band as an example, with a rectangular cross section, the long side W preferably being in the range of 2 to 20 microns and the short side T preferably being in the range of 400 nm to 2 microns.
Example 2
The embodiment provides another asymmetric three-dimensional micro-ring whispering gallery mode cavity with higher structural freedom degree, which can be used for realizing free regulation and control of polarization states, including free transformation, identification, separation and generation of linear polarization, circular polarization, elliptical polarization and left-handed and right-handed spin polarization states.
The structure of the asymmetric microcavity is shown in fig. 6, which is a perspective view with the tilted light wave resonance trace identified. The microcavity cavity has a quadrilateral cross section, and the length of the cross section along the z-axis is defined as W. The whole structure is in a shape of a frustum with a big top and a small bottom, or the diameter of the upper part and the lower part is defined as D B 、D T . The deflection angle of the central axis and the z axis of the quadrangular section is defined as theta. The angle is not drastically changed as in the previous structure, and is generally 1-20 degrees. The deflection effect may also take an asymmetric form, e.g. θ at point A 1 Point B is theta 2 The middle is gradually transited, and in the evolution of the azimuth angle of 180-360 degrees, the original section structure is regressed, so that the closed loop is realized. Fig. 7 shows a schematic diagram of a cross-sectional structure of the embodiment at points a, B and transition X, wherein the direction is a counterclockwise propagation view angle of the light wave. Fig. 8 shows the deflection angle as a function of azimuth angle.
In addition to the introduction of deflection angles, the structure has an upper and a lower unequal width design of a section, and the lengths of the two bottom edges of the upper bottom and the lower bottom are respectively T1 and T2. Equivalent refractive index profile n of mode along z-axis eff (z) modulation can be obtained and the optical wave transmission path can be converted from the original mediocre in-plane resonance to an inclined out-of-plane resonance path according to the fermat principle, as shown in fig. 6. Resonance forming closureIs inclined at an angle beta to the original resonant surface.
The spin-orbit coupling phenomenon of photons in this structure is analyzed as follows. The photon motion track is separated from the original plane and inclined, and a strong enough wave vector component K appears along the axial direction z . Therefore, the orbital angular momentum originally present in the whispering gallery mode resonance can be combined with the wave vector K z The spin angular momentum carried is coupled with each other, and the coupling strength is related to the magnitude of the tilt angle beta. In oblique propagation, photons evolve stepwise from the original linear polarization to elliptical polarization. Fig. 9 shows the evolution of the resonant mode in the poincare sphere in this structure, and the propagating light can complete a closed loop with any elliptical polarization. The direction of evolution of photons on poincare spheres is determined by the spin of photons within the microcavity. The upper hemisphere and the lower hemisphere distinguish corresponding left-handed elliptical polarized light and right-handed elliptical polarized light. The evolution of photons in the upper and lower hemispheres is determined by the direction of propagation (i.e., clockwise, counterclockwise propagation) of the photons within the microcavity. The two propagation directions are also embodied as two different sets of propagation trajectories in the microcavity.
Therefore, the asymmetric properties of the structure, including the deflection angle, the asymmetry of the cross section and the like, determine the ellipsometry and the geometric phase of the resonance light field. According to Pancharam-Berry (PB) phase theory [ Journal of Modern Optics,1987,34,1401-1407], photons complete a closed resonant loop, starting from point A and returning to point A (referred to herein as point A') to produce a geometric phase of
<A|A'>＝exp(-iΩ/2)，
Where Ω is the solid angle formed by the evolution trace on the poincare sphere.
Under the condition of meeting resonance, the optical field at the point A can be expressed as the superposition interference of the original point A and the component back to the point A after propagation, namely
I＝||A>e iΦ +|A'>e -iΦ |，
Where Φ is the dynamic phase brought about by the propagation. The interference phenomenon must take into account two phase superposition effects,
I＝2+2|<A|A'>cos(arg<A|A'>-2Φ|。
therefore, compared with the traditional planar micro-ring cavity, the resonance wavelength shifts with the increase of the geometric phase.
Fig. 10 (a) shows the corresponding azimuth angles of different ellipsoids in poincare sphere, thus resulting in a significant difference in geometric phase. The left-handed and right-handed input light correspond to opposite geometric phases, causing opposite signs of shift in resonance wavelength. From fig. 10 (b), it can be seen that under different ellipsometric influences, the resonance wavelength shifts under the original influence. Based on this characteristic, the structure can act as a filter, distinguishing input light carrying different spin properties.
FIG. 11 is a simulation result of the structure calculated using a three-dimensional electromagnetic field simulation tool. The periodic formants are represented in the spectrum in fig. 11 (a). Fig. 11 (b) shows a side view of the resonant light field distribution, and the out-of-plane tilt of the resonant locus is evident. FIG. 11 (c) is a graph showing polar coordinate distribution of polarization states at different z-axis positions, wherein the resonant mode exhibits a distinct elliptical polarization property and is dependent on the position.
The embodiment can be widely applied to different wave bands such as visible light, near infrared, middle infrared and the like. A unified adjustment can be made for all design parameters corresponding to the band. The communication C-band (about 1530-1565 nm) is exemplified below. The cross section is quadrilateral, the height of the top of the cross section, i.e. the distance W of the top from the substrate, is preferably in the range of 2 micrometers to 20 micrometers, and the upper T1 and lower T2 bottoms are preferably in the range of 400 nanometers to 2 micrometers.
Example 3
A method for preparing a three-dimensional asymmetric microcavity device for light field modulation, which is used for preparing the device of the embodiment 1 or the embodiment 2.
For the special three-dimensional microcavity structure, the traditional top-down photoetching technology is difficult to be adopted in the preparation process, and the 3D printing forming technology based on laser scanning is an alternative scheme. Because of the insufficient structural accuracy achievable by conventional ultraviolet exposure 3D printing technology, the preferred preparation scheme is to realize three-dimensional printing or ablation technology under two-photon polymerization based on femtosecond laser.
As shown in fig. 12, which is a schematic diagram of a two-photon polymerization process, a photoresist 105 is deposited on a substrate 104 and is processed by using a high energy density beam 101 focused by a pulse laser, preferably having ultra-short femtosecond pulses (with a pulse width of about-10-1000 fs) and a high energy density. The excitation wavelength is near infrared band, preferably 700-1000nm, ensuring that the energy after two photons are absorbed simultaneously can modify the photoresist 105. The volume of the effective focal point 102 of two-photon polymerization is greatly reduced compared with the volume of conventional single photon excitation under optical focusing. The three-dimensional microcavity structure 103 can be formed by three-dimensional point-by-point scanning exposure processing through a two-dimensional high-speed scanning rotating mirror and a precise ceramic piezoelectric platform, and the structural precision can be less than 100nm, so that the requirements are met. The processed substrate 104 can be a conventional glass sheet, a quartz sheet or a silicon wafer, or can be a chip processed with a planar optical waveguide loop, so as to realize heterogeneous integration.
Preferred photoresist materials 105 are SU-8, orcocomp, and nanoscales IP-Dip, IP-780, IP-G780, or IP-S. There is a certain difference in refractive index between different types of photoresists. Outside the microcavity is a low refractive index environment, which can be air, liquid, low refractive index filled polymer, etc. If a higher refractive index difference is required to be manufactured, a microcavity structure with smaller volume is realized, and oxide materials with high refractive index and low absorption, such as TiO, can be uniformly deposited on the inner surface and the outer surface at the later stage by means of Atomic Layer Deposition (ALD) technology 2 、HfO 2 . In order to achieve a sufficiently large axial refractive index difference, a secondary printing may also be implemented, enabling a splice of two different refractive index materials. In addition to the microcavity body, for supporting the three-dimensional structure, additional preparation of a supporting frame, preferably a frustum structure, is required, and the contact area with the microcavity is reduced to control scattering loss.
As a verification test of the present invention, the device structure of example 1 was molded on a quartz substrate with a lateral 10nm scanning accuracy based on a femtosecond laser beam of 780nm wavelength using a two-photon polymerization lithography commercial instrument. Then, the solution was treated with a developing machine for 13 minutes, washed with isopropyl alcohol, and finally, the remaining adhering liquid was removed with a supercritical dryer. Fig. 13 is an electron scanning microscope image of the device produced.
Example 4
The embodiment is an application of a three-dimensional asymmetric microcavity device for light field regulation. The following description will be made mainly with respect to the microcavity structure of embodiment 1, which is applied to a passive device.
A passive device employing a three-dimensional asymmetric microcavity device for optical field conditioning as described in example 1 coupled with an optical fiber or planar optical waveguide, the structure of which is shown in fig. 14 (a). Tapered fiber 201, preferably realized by localized heating and stretching of a common single mode fiber, preferably 2 μm or less in diameter as an input fiber, ensures that a sufficiently strong evanescent field is present to interact with microcavity cavity 202. Wherein the microcavity cavity 202 is supported by the support 203 and coupling is accomplished by a micromanipulator near the microcavity cavity 202. Alternatively, another tapered fiber 201 is used on the other side of the microcavity to achieve out-coupling. Fig. 14 (b) is an optical microscope image of coupling using tapered optical fibers.
Fig. 15 is a schematic diagram of a microcavity characterization system comprising a wavelength tunable laser 301, a polarization control module 302, a coupling module 303 of an input fiber to a tapered fiber or on-chip optical waveguide, and optionally a photodetector or spectrometer 304, an analyzer module or polarimeter 305 for analysis of the output signal. Furthermore, the device coupling alignment requires the aid of an optical microscopy imaging section, including a high magnification objective 306 and an imaging camera 307.
Fig. 16 (a) is a graph of the results of measurements performed on the device of example 1 using the microcavity characterization system measurements described above. A wavelength tunable laser of a communication c-band is coupled into an optical fiber for excitation, and a photoelectric detector is used for acquisition, so that a transmission spectrum with a periodic whispering gallery mode can be obtained. The polarization state of collimated incident light can be measured in a rotated waveplate method based on a polarimeter, which is embodied as a distribution in polar coordinates. As shown in fig. 16 (b), when the principal axis orientation and ellipsometry are analyzed, the corresponding polarization exists at about 90 degrees when the two characteristic points A, B are coupled, and the linear polarization property is maintained, so that the regulation function of the microcavity structure of embodiment 1 on polarization is proved.
Example 5
On the basis of embodiment 4, as another application, when used as a passive on-chip filter device, the preferred solution is integration with a conventional planar waveguide. As shown in fig. 17, the waveguide is preferably a channel waveguide 204 having a rectangular cross-section, preferably a single-mode waveguide, and the material may be a conventional guided wave material transparent at the operating wavelength, such as silicon, silicon nitride, silicon dioxide, indium phosphide, a polymer, or the like. The side view of the opposite arrangement is shown in fig. 17 (a), which exemplifies the microcavity structure of embodiment 1, and is of course equally applicable to the microcavity structure of embodiment 1. The trench is formed by etching the material of the low refractive index bottom cladding layer 205 in the microcavity region, introducing the pillars 203, connecting the microcavity 202 with the bottom of the trench of the bottom cladding layer 205 through the pillars 203, and then positioning the channel waveguide 204 outside the microcavity junction 202 and in contact with the surface of the bottom cladding layer 205. Thus, the relative position regulation and control of the waveguide and the microcavity device in the vertical direction can be ensured. The coupling-in waveguide and the coupling-out waveguide are separated from the edge of the microcavity by a sub-wavelength gap. Fig. 17 (b) and 17 (c) illustrate designs that couple out at different azimuth angles, with free modulation of the output polarization achieved by adjusting the azimuth angle prescribed by the coupling-out waveguide 206. The coupling-out waveguide is a curved optical waveguide which is coupled at any azimuth angle.
In the fiber or waveguide coupling schemes described above, the photon resonance closed loop is parallel to the plane of the substrate or inclined at a small angle.
Example 6
An on-chip multiplexing waveguide coupling device adopts a multiplexing scheme, adopts the microcavity structure of the embodiment 2, and has a structure schematic shown in fig. 18, wherein the microcavity 401 is integrally rotated by 90 degrees, a resonant optical closed loop is almost vertical to a substrate, and zero-interval coupling is performed between the waveguide array 402 and the microcavity 401. Given that the axial structural length W is sufficiently large, multiple sets of axial modes are embodied as different evolution tracks in the poincare sphere, and can be used for optical field regulation under multiplexing. By the transformation, the components of light can realize axial resolution, can be simultaneously coupled with a plurality of waveguides, and the coupling result is that a plurality of groups of components with different polarization characteristics are generated, so that multiplexing is realized.
Example 7
The technical scheme of the invention is not limited to passive on-chip devices, but can also be used as an active light-emitting device, especially a laser and a broad spectrum light source, so as to realize the polarization regulation of output light. The specific difference from the above is that: in the preparation step of the photoresist in the preparation process, the active material is uniformly doped into the photoresist. Preferred active materials are fluorescent dyes, up-conversion materials, aggregation-induced emission (AIE) molecules, colloidal quantum dots, or optical materials with strong nonlinear properties, etc. This way, a resonance signal can be formed by photoluminescence by pumping with an external light source. The output light may be collected by a waveguide or an optical fiber. The device can be used as a multimode lasing light source to realize specific spin orbit coupling in different resonance orbits, so that different polarization properties are carried among modes, the device can be used for free space optical communication, on-chip optical communication optical interconnection, optical calculation, optical sensing and other applications, and also can be used as a quantum light source to generate polarization entangled photons for processing single photon characteristics and be used for quantum communication and quantum calculation.
Fig. 19 shows a special case of the simulation result obtained by calculating the three-dimensional electromagnetic field simulation tool COMSOL Multiphysics. It can be seen that different axial positions Z can be selected 1 、Z 2 When different linear or elliptical polarizations are obtained, wherein the properties of the left-hand and right-hand elliptical polarizations can be distinguished along the propagation direction.
The structural scheme of the characterization system based on the active three-dimensional microcavity is shown in fig. 20. The pump laser 501 is preferably a pulsed laser with a relatively high energy density and a relatively low repetition rate. Spatially selective excitation of the microcavity is controllable by the reflective spatial light modulator 502, focused by the objective 503 onto the surface of the active microcavity device 504 to achieve photoluminescence, and the excitation position is also adjustable by the electronically controlled displacement platform 505. The multiplexed output optical signal may be output after being converted into free space by an array coupling system 506, such as a microlens array, an optical fiber array, a waveguide array, etc., and finally passing through a filter 507.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (7)
1. A three-dimensional asymmetric microcavity device for light field regulation, characterized in that: the optical micro-ring cavity comprises a substrate and an optical micro-ring cavity positioned on the substrate, wherein the section of the optical micro-ring cavity gradually deflects along with the change of the azimuth angle phi of the micro-ring according to the section deflection angle theta, and a closed loop connected end to end is formed; the cross section of the optical micro-ring cavity is a cross section passing through the ring center along the axial direction of the optical micro-ring cavity, and the cross section deflection angle theta is an included angle between the connecting line direction of the midpoint of the short side of the cross section and the axial direction of the substrate; the section deflection angle θ satisfies: the angle theta of the section is larger than or equal to 0 degree and smaller than or equal to 90 degrees, the deflection angle theta of the section changes along with the azimuth angle phi from 0 degree, and the maximum value reaches 90 degrees after the azimuth angle phi changes by 180 degrees; the section then evolves again through the azimuth angle in the interval of 180-360 degrees, and finally the closed loop of end to end is realized.
2. The three-dimensional asymmetric microcavity device for light field modulation of claim 1, wherein: the cross section is rectangular.
3. The three-dimensional asymmetric microcavity device for light field modulation of claim 2, wherein: the diameter of the optical micro-ring cavity is 3-1000 microns, the long side of the rectangle is 2-20 microns, and the short side of the rectangle is 400 nanometers-2 microns.
4. The method for manufacturing the three-dimensional asymmetric microcavity device for light field regulation and control according to any one of claims 1 to 3, which is characterized by comprising the following steps: the optical micro-ring cavity is prepared on a substrate by adopting a two-photon polymerization or ablation 3D printing technology realized based on laser scanning.
5. A passive on-chip device, characterized by: a three-dimensional asymmetric microcavity device for optical field tuning as claimed in any one of claims 1 to 3 and a planar waveguide or optical fiber.
6. A multiplexing device, characterized by: the three-dimensional asymmetric microcavity device for light field regulation and control comprises the three-dimensional asymmetric microcavity device for light field regulation and control as claimed in any one of claims 1-3 and a plurality of waveguides, wherein the waveguides form a waveguide array, the waveguides are in contact with the side wall of the three-dimensional asymmetric microcavity device for light field regulation and control, and the extending direction of the waveguides is parallel to the substrate of the three-dimensional asymmetric microcavity device for light field regulation and control.
7. An active three-dimensional microcavity device, characterized by: the three-dimensional asymmetric microcavity device for light field regulation and control comprises the three-dimensional asymmetric microcavity device for light field regulation and control according to any one of claims 1-3, wherein the cavity of the three-dimensional asymmetric microcavity device for light field regulation and control contains an active material, and the active material comprises at least one of fluorescent dye, up-conversion material, aggregation-induced emission molecules, colloidal quantum dots or material with strong nonlinear optical characteristics.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103972789A (en) * | 2014-04-04 | 2014-08-06 | 南京邮电大学 | Nitride asymmetric whispering gallery mode optical microcavity device and preparation method thereof |
| CN104253372A (en) * | 2013-06-27 | 2014-12-31 | 中国科学院化学研究所 | Whispering gallery mode photonic device and preparation method thereof |
| CN104868352A (en) * | 2015-06-03 | 2015-08-26 | 吉林大学 | Three-dimensional asymmetric miniature resonant cavity polymer single-mode laser |
| CN106058640A (en) * | 2016-08-09 | 2016-10-26 | 中国科学院半导体研究所 | Stable and directional output microcavity laser |
| CN108646350A (en) * | 2018-03-30 | 2018-10-12 | 中国科学技术大学 | Mechanical vibrator microcavity coupling body and use its optical circulators |
| CN109254349A (en) * | 2018-01-04 | 2019-01-22 | 广东工业大学 | A kind of spectrum regulation device with ring resonator |
| CN111969396A (en) * | 2020-07-27 | 2020-11-20 | 中国科学院西安光学精密机械研究所 | High-integration intermediate infrared broadband super-continuum spectrum generation device and method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102012502B1 (en) * | 2017-09-26 | 2019-10-21 | 경북대학교 산학협력단 | Designing method of dielectric cavity |
-
2021
- 2021-12-22 CN CN202111581925.6A patent/CN114153032B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104253372A (en) * | 2013-06-27 | 2014-12-31 | 中国科学院化学研究所 | Whispering gallery mode photonic device and preparation method thereof |
| CN103972789A (en) * | 2014-04-04 | 2014-08-06 | 南京邮电大学 | Nitride asymmetric whispering gallery mode optical microcavity device and preparation method thereof |
| CN104868352A (en) * | 2015-06-03 | 2015-08-26 | 吉林大学 | Three-dimensional asymmetric miniature resonant cavity polymer single-mode laser |
| CN106058640A (en) * | 2016-08-09 | 2016-10-26 | 中国科学院半导体研究所 | Stable and directional output microcavity laser |
| CN109254349A (en) * | 2018-01-04 | 2019-01-22 | 广东工业大学 | A kind of spectrum regulation device with ring resonator |
| CN108646350A (en) * | 2018-03-30 | 2018-10-12 | 中国科学技术大学 | Mechanical vibrator microcavity coupling body and use its optical circulators |
| CN111969396A (en) * | 2020-07-27 | 2020-11-20 | 中国科学院西安光学精密机械研究所 | High-integration intermediate infrared broadband super-continuum spectrum generation device and method |
Non-Patent Citations (1)
| Title |
|---|
| Spin–orbit coupling of light in asymmetric microcavities;LB Ma et al.;《Nature Communications》;第1-6页 * |
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