CN111399117B - Hybrid integrated silicon nitride micro-ring resonant cavity and preparation method thereof - Google Patents
Hybrid integrated silicon nitride micro-ring resonant cavity and preparation method thereof Download PDFInfo
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- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
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Abstract
The invention discloses a hybrid integrated silicon nitride micro-ring resonant cavity and a preparation method thereof, wherein the silicon nitride micro-ring resonant cavity comprises: a silicon nitride waveguide; the silicon nitride micro-ring resonant cavity is arranged to form coupling connection with the silicon nitride waveguide; a wedge-shaped vertical coupler comprising: the silicon nitride Bragg grating coupler is connected with the silicon nitride waveguide through a wedge-shaped coupler, the polycrystalline silicon wedge-shaped coupling structure is arranged on the silicon nitride Bragg grating coupler and/or the wedge-shaped coupler, and the III-V family wedge-shaped coupling structure is arranged on the polycrystalline silicon wedge-shaped coupling structure; and the III-V waveguide is arranged and connected with the III-V wedge-shaped coupling structure. The silicon nitride micro-ring resonant cavity provided by the invention can realize vertical coupling between the III-V group waveguide and the silicon nitride waveguide. The designed hybrid integrated micro-ring resonant cavity has the comprehensive advantages of low loss, high polarization suppression ratio, high integration level, simple preparation process and the like.
Description
Technical Field
The invention relates to the field of optics and micro-nano systems, in particular to a hybrid integrated silicon nitride micro-ring resonant cavity and a preparation method thereof.
Background
The basic working principle of the resonant integrated optical gyroscope is to detect the resonant frequency difference of two clockwise and clockwise beams caused by the Sagnac effect in the rotation process of a Waveguide Ring Resonator (WRR), thereby realizing the detection of the rotation angular velocity. The main devices of the laser device comprise a laser device, a phase modulator, a ring-shaped resonant cavity and a detector. The ring resonator is the core device of the integrated optical gyroscope, and the performance parameters of the ring resonator determine the ultimate sensitivity of the whole optical gyroscope. At present, international and domestic researches on integrated optical gyroscopes generally focus on how to prepare high-quality micro-ring resonant cavities, and mainly focus on how to reduce waveguide transmission loss and how to inhibit secondary polarization states. The silicon nitride waveguide with high width-depth ratio is an excellent solution for preparing a high-performance micro-ring resonant cavity. The high-aspect-ratio structure can realize low-loss transmission of a waveguide single TE mode. However, silicon nitride is not capable of preparing active devices, and how to realize monolithic integration of passive and active devices is still a difficult problem.
Therefore, there is a need to provide a new hybrid integrated silicon nitride micro-ring resonator capable of realizing passive and active hybrid integration, so as to realize a truly monolithic integrated optical gyroscope.
Disclosure of Invention
Technical problem to be solved
The invention provides a hybrid integrated silicon nitride micro-ring resonant cavity and a preparation method thereof, which at least partially solve the technical problems.
(II) technical scheme
The invention provides a hybrid integrated silicon nitride micro-ring resonant cavity on one hand, which comprises:
a silicon nitride waveguide;
the silicon nitride micro-ring resonant cavity is arranged to form coupling connection with the silicon nitride waveguide;
a wedge-shaped vertical coupler comprising:
the silicon nitride Bragg grating coupler is connected with the silicon nitride waveguide through a wedge-shaped coupler;
the polycrystalline silicon wedge-shaped coupling structure is arranged on the silicon nitride Bragg grating coupler and the wedge-shaped coupler; and
the III-V family wedge-shaped coupling structure is arranged on the polycrystalline silicon wedge-shaped coupling structure;
the III-V group waveguide is connected with the III-V group wedge-shaped coupling structure;
the III-V group waveguide is connected with the silicon nitride waveguide through three layers of wedge-shaped vertical couplers, so that the integration of active and passive devices is realized.
In some embodiments, the silicon nitride micro-ring resonator further comprises: the silicon nitride micro-ring resonator comprises a substrate silicon wafer, wherein a silicon dioxide layer is deposited on the substrate silicon wafer, and a silicon nitride core layer is formed by a silicon nitride waveguide, a silicon nitride Bragg grating coupler, a wedge-shaped coupler and a silicon nitride micro-ring resonator and is arranged on the silicon dioxide layer.
In some embodiments, the thickness of the silicon dioxide layer is greater than or equal to 2 μm.
In some embodiments, the wedge coupler is a waveguide with a wedge structure, the narrow waveguide end of the waveguide is connected with the silicon nitride waveguide, and the wide waveguide end is matched with the structural size of the silicon nitride bragg grating coupler.
In some embodiments, the thickness of the polysilicon wedge coupling structure is 400-600 nm.
In some embodiments, the silicon nitride waveguide structure is a rectangular waveguide structure.
In some embodiments, the waveguide structure at the coupling connection between the silicon nitride waveguide and the micro-ring resonator is a straight waveguide or a curved waveguide structure.
The invention also provides a preparation method of the hybrid integrated silicon nitride micro-ring resonant cavity, which comprises the following steps:
depositing a silicon nitride layer on the silicon dioxide layer of the substrate silicon wafer;
preparing a silicon nitride waveguide, a silicon nitride Bragg grating coupler, a wedge-shaped coupler and a silicon nitride micro-ring resonant cavity on the silicon nitride layer to obtain a silicon nitride core layer;
depositing a polysilicon layer on the silicon nitride core layer, and preparing a polysilicon wedge-shaped coupling structure on the polysilicon layer;
and bonding a III-V group derivation layer on the polycrystalline silicon layer, and preparing a III-V group wedge-shaped coupling structure and a III-V group waveguide on the III-V group derivation layer.
Further, wherein:
in some embodiments, the coupling distance between the silicon nitride waveguide and the silicon nitride micro-ring resonator is determined according to the set transmission loss of the micro-ring and the length of the resonator.
In some embodiments, the period, duty cycle, etch depth, and number of grating periods of the silicon nitride bragg grating coupler are determined based on the diffraction capability of the grating, the directivity of the grating, and the influence of the overlap integral of the grating and the optical field on the grating coupling efficiency.
(III) advantageous effects
According to the technical scheme, the silicon nitride micro-ring resonant cavity and the preparation method thereof provided by the invention have the following beneficial effects:
(1) the hybrid integrated silicon nitride micro-ring resonant cavity is prepared on a silicon dioxide layer of a silicon substrate, and can be finally integrated with a laser and a detector on the same substrate by means of mature silicon-based integrated optical development, so that the real chip-level size of the resonant gyroscope is realized. In addition, the subsequent demodulation circuit can also be realized by means of a mature silicon-based CMOS circuit;
(2) the high silicon nitride waveguide is a waveguide structure with the lowest transmission loss known at present, and the low waveguide transmission loss means higher fineness of the device;
(3) the coupling between the optical waveguides is realized through a horizontal coupling structure, the control on the light propagation direction can be realized through grating coupling, so that the possibility of three-dimensional integration of devices is provided, and the surface fluctuation of the material deposited by LPCVD is only a few tenths of nanometers, so that the insertion loss of the coupler can be greatly reduced;
(4) through the bonding technology, other processes can be further carried out on the vertical coupling device, the implementation of subsequent processes is facilitated, and the high integration degree of the device is greatly facilitated.
Drawings
FIG. 1 is a diagram illustrating a wedge-shaped vertical coupler construction according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a layered structure of a hybrid integrated silicon nitride micro-ring resonator according to an embodiment of the present invention;
FIG. 3 is a top view of a layered front side of the hybrid integrated silicon nitride micro-ring resonator shown in FIG. 2;
fig. 4 is a flow chart of a method for manufacturing a silicon nitride micro-ring resonator according to an embodiment of the invention.
Description of the symbols:
101-a silicon nitride bragg grating coupler; 102-a wedge coupler;
103-straight waveguide; 104-micro ring resonant cavity;
201-a polysilicon wedge coupling structure;
301-III-V family wedge coupling structures; a 302-III-V straight waveguide;
Detailed Description
In order to reduce the loss of light during transmission, the commonly used waveguide material is a silicon nitride waveguide with high aspect ratio, and the transmission loss of the silicon nitride waveguide can be 2 to 3 orders of magnitude lower than that of the traditional silicon waveguide. However, silicon nitride cannot be used for manufacturing lasers and photodetectors due to the inherent characteristics of silicon nitride, and therefore, the integration of the whole gyroscope is not challenged before.
The process of introducing light from one optical element into another is called optical coupling, and the exchange of energy that causes the power of one mode to be completely transferred into another mode of the same waveguide or between two waveguides is called optical waveguide coupling.
The wedge coupler is also called wedge coupler, and is formed by making a section of waveguide into a wedge-shaped optical waveguide region. The wedge-shaped spot-mode converter overcomes the difference caused by the aspects of effective refractive index, core diameter size, symmetry and the like by using the wedge-shaped waveguide, improves the degree of mode field matching and reduces the end face reflection loss, thereby coupling the light waves into the waveguides with different sizes.
In the grating vertical coupling structure, the diffraction grating on the surface of the waveguide is used for diffracting the incident light wave vertical to the surface of the waveguide into another waveguide structure, so that the propagation direction of the light can be changed.
The invention can fully utilize the integratability of the silicon waveguide and the low loss advantage of the silicon nitride waveguide by virtue of the vertical coupling structure of the silicon waveguide and the silicon nitride waveguide. Compared with the waveguide horizontal coupling, the coupling distance of the waveguide vertical coupling structure is more accurately controlled, and the device performance is more consistent with the design value. Therefore, the gyroscope optical waveguide chip has a wider application prospect.
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
In one aspect, the present invention provides a hybrid integrated silicon nitride micro-ring resonator, comprising:
a silicon nitride waveguide;
the silicon nitride micro-ring resonant cavity is arranged to form coupling connection with the silicon nitride waveguide;
a wedge-shaped vertical coupler comprising:
the silicon nitride Bragg grating coupler is connected with the silicon nitride waveguide through a wedge-shaped coupler;
the polycrystalline silicon wedge-shaped coupling structure is arranged on the silicon nitride Bragg grating coupler and the wedge-shaped coupler; and
the III-V family wedge-shaped coupling structure is arranged on the polycrystalline silicon wedge-shaped coupling structure;
the III-V group waveguide is connected with the III-V group wedge-shaped coupling structure;
the III-V group waveguide is connected with the silicon nitride waveguide through three layers of wedge-shaped vertical couplers, so that the integration of active and passive devices is realized.
In some embodiments, the silicon nitride micro-ring resonator further comprises:
a substrate silicon wafer on which a silicon dioxide layer is deposited;
the silicon nitride waveguide, the silicon nitride Bragg grating coupler, the wedge-shaped coupler and the silicon nitride micro-ring resonant cavity form a silicon nitride core layer which is arranged on the silicon dioxide layer;
further, the thickness of the silicon dioxide layer is greater than or equal to 2 μm.
In some embodiments, the wedge-shaped coupler is a waveguide with a wedge-shaped structure (gradually changing width), a narrow waveguide end of the waveguide is connected with a silicon nitride waveguide, a wide waveguide end is matched with the structure size of the silicon nitride bragg grating coupler, and the waveguide limiting coefficient is adjusted by changing the width of the waveguide, so that the heterogeneous waveguide coupling is realized.
In some embodiments, the thickness of the polysilicon wedge coupling structure layer is 400-600 nm.
In some embodiments, the silicon nitride waveguide structure is a rectangular waveguide structure, and such a silicon nitride waveguide structure can effectively reduce loss caused by rough sidewalls of the waveguide due to etching.
In some embodiments, the waveguide structure at the coupling connection between the silicon nitride waveguide and the micro-ring resonator is a straight waveguide or a bent waveguide structure, so as to reduce a coupling mismatch factor and reduce insertion loss of the evanescent wave coupler.
In view of this, in a first exemplary embodiment of the present invention, a gyroscope optical waveguide chip is provided. In combination with the above embodiment, specifically, the method includes:
a substrate silicon wafer, on which a silicon dioxide layer, a silicon nitride core layer, a polysilicon layer, a bonding layer and a III-V group derivation layer are deposited, and a wedge-shaped vertical coupler is prepared at the end of a silicon nitride waveguide prepared on the substrate silicon wafer, wherein:
the silicon nitride core layer is positioned on the upper layer of the thermal oxygen silicon dioxide, and a silicon nitride waveguide core area structure is prepared on the silicon nitride core layer, and the silicon nitride optical waveguide core area structure comprises: the Bragg grating coupler 101, the wedge coupler 102, the straight waveguide 103 and the micro-ring resonant cavity 104 need to accurately control the grating period so as to control the coupling wavelength;
the polycrystalline silicon layer is positioned above the ridge-shaped silicon nitride optical waveguide, a polycrystalline silicon wedge-shaped coupling structure 201 is prepared on the polycrystalline silicon layer, and the thickness of the polycrystalline silicon wedge-shaped coupling structure is required to be accurately controlled so as to control the coupling distance between the upper waveguide and the lower waveguide;
the III-V group leading-out layer is positioned above the polysilicon coupling area, and is provided with a III-V group wedge-shaped coupling structure 301 and a III-V group waveguide 302;
and the silicon nitride Bragg grating coupler 101, the polysilicon wedge-shaped coupling structure 201 and the III-V family wedge-shaped coupling structure 301 jointly form the wedge-shaped vertical coupler, the silicon nitride micro-ring resonant cavity 104 positioned at the bottom layer realizes the coupling input and output of light through the wedge-shaped vertical couplers at two sides, and the wedge-shaped coupling structure 301 of the wedge-shaped vertical coupler is used for guiding in and out an optical path.
It should be noted that the wedge coupler is implemented by gradually changing the waveguide width, and the limiting coefficient of the waveguide structure can be changed by changing the waveguide width.
Fig. 1 is a layered construction diagram of a gyroscope optical waveguide chip according to an embodiment of the present invention, in which a silicon nitride core layer, a polysilicon layer, and a III-V group lead-out layer are sequentially stacked and combined from bottom to top. Fig. 2 is a schematic diagram of a layered structure shown in fig. one. In addition, the structures corresponding to the 101-302 reference numerals are obtained by etching a part of the height of the silicon nitride on the silicon nitride of the SOI substrate 1 (as shown in fig. 2), which is schematically illustrated in fig. 2.
The following describes in detail various parts of the optical waveguide vertical coupling chip shown in the present embodiment with reference to the drawings.
In this embodiment, a silicon nitride core layer is fabricated with a ridge-shaped silicon waveguide core region structure (referred to as a core region structure for short), the core region structure is formed by etching, as shown in fig. 2, the refractive index of the silicon nitride core layer at a wavelength of 1.55 μm is 3.471, which is 58% different from the refractive index of the polysilicon layer, so that the high refractive index difference can effectively limit light in the core region structure to realize miniaturization of the device structure. In a preferred embodiment, the rib waveguide core structure has a rectangular cross-section, with a rib height of 350nm and a width of 400nm, as shown in FIG. 2. And etching a grating pattern at the tail end of the silicon nitride waveguide, wherein the grating interval is 560 nm.
In this embodiment, a polysilicon layer is covered over the silicon nitride waveguide, the polysilicon layer has a thickness of 80nm and fills the silicon nitride grating, and the refractive index at 1.55 μm wavelength is 1.457.
In this embodiment, the thickness of the polysilicon layer needs to be precisely controlled to achieve coupling with the silicon nitride core layer and the III-V group derived layer.
In this example, the thickness of the III-V group derived layer was 800 nm.
In this embodiment, the silicon nitride core layer is prepared with a waveguide micro-ring resonator 104, and the micro-ring resonator 104 is located on one side of the straight waveguide 103. The refractive index of silicon nitride is 1.97, which is 26% different from the refractive index of cladding silica. In a preferred embodiment, as shown in fig. 2, the cross section of the silicon nitride optical waveguide core region structure is rectangular, and has a height of 350nm and a width of 400nm, and the high aspect ratio waveguide structure can ensure that 1.55 μm of light waves realize single-mode transmission in the waveguide.
In this embodiment, a low-loss transmission between the III-V waveguide and the silicon nitride waveguide may be finally achieved with the bragg grating coupler.
In this embodiment, the III-V waveguides and the silicon nitride waveguides are integrated by three layers of wedge-shaped vertical couplers between them. The scheme can realize the hybrid integration between the silicon nitride waveguide with high polarization rejection ratio and low loss and the active device, and by means of the low loss characteristic of the three-layer wedge-shaped vertical coupler, the loss of the hybrid integrated silicon nitride micro-ring resonant cavity is very small, so that the miniaturization of the integrated optical gyroscope can be further realized on the premise of reaching the tactical inertial navigation precision.
It is also noted that the rectangular silicon nitride waveguide structure is a single polarization state single mode structure, which can sufficiently suppress the polarization state fluctuation noise commonly existing in the silicon waveguide micro-ring resonator.
In another aspect, for the silicon nitride micro-ring resonator, the invention provides a method for preparing the silicon nitride micro-ring resonator, which includes:
depositing a silicon nitride layer on the silicon dioxide layer of the substrate silicon wafer;
preparing a silicon nitride waveguide, a silicon nitride Bragg grating coupler, a wedge-shaped coupler and a silicon nitride micro-ring resonant cavity on the silicon nitride layer to obtain a silicon nitride core layer;
depositing a polysilicon layer on the silicon nitride core layer, and preparing a polysilicon wedge-shaped coupling structure on the polysilicon layer;
and bonding a III-V group derivation layer on the polycrystalline silicon layer, and preparing a III-V group wedge-shaped coupling structure and a III-V group waveguide on the III-V group derivation layer.
In view of the above, in a second exemplary embodiment of the present invention, a novel method for preparing a hybrid integrated silicon nitride micro-ring resonator is provided, which includes:
step S21: a silicon nitride waveguide layer (namely a silicon nitride core layer) structure is prepared on a thermal oxidation silicon dioxide layer of a silicon wafer.
In this embodiment, a high-precision polished silicon wafer is prepared and a substrate is cleaned, and the wafer cleaning process includes: firstly, putting a silicon wafer into a cleaning beaker, then pouring a proper amount of hydrogen peroxide, adding a proper amount of sulfuric acid according to the ratio of 1: 3 of the sulfuric acid to the hydrogen peroxide, reacting and removing pollutants on the silicon wafer through an oxidation reduction reaction, finally washing with deionized water for 10-15 times to remove sulfides on the surface of the wafer, and drying with a nitrogen gun to ensure that the surface of the wafer has no particles or water stains;
and the thermal oxidation silicon dioxide layer is more compact than the thermal oxidation silicon dioxide layer grown at normal temperature, and has less loss defects. A silicon nitride layer is then deposited to a thickness by Low Pressure Chemical Vapor Deposition (LPCVD). Coating photoresist with a certain thickness on the surface of a substrate, exposing the photoresist on the surface of the substrate by adopting ultraviolet lithography, and leaving a Bragg grating coupler 101, a wedge-shaped coupler 102, a straight waveguide 103 and a micro-ring 104 glue layer after developing and fixing;
and completely etching the silicon nitride layer by an inductively coupled plasma etcher (ICP), and cleaning and removing the photoresist to finish the pattern transfer from the photoresist pattern to the silicon nitride layer.
Step S22: and preparing a polycrystalline silicon wedge structure.
In this embodiment, polysilicon of a certain thickness is deposited on the surface of the wafer with the silicon nitride waveguide structure prepared by LPCVD, and then the surface is polished to make the surface smooth. Coating photoresist with a certain thickness on the surface of the wafer, and adopting ultraviolet lithography exposure, developing and fixing to leave a polycrystalline silicon wedge-shaped structure 201 glue layer;
and completely etching the polysilicon layer by an inductively coupled plasma etcher (ICP), and cleaning and removing photoresist to finish the pattern transfer from the photoresist pattern to the silicon nitride layer.
It is noted that the thickness of the polysilicon layer can be controlled by precisely controlling the flow rate and temperature of LPCVD
Step S23: and bonding III-V group materials on the polished polysilicon layer and preparing a III-V group wedge-shaped waveguide structure and a straight waveguide structure.
In the embodiment, the III-V group layer is combined with the wafer through bonding, the bonded III-V group layer is thinned through grinding and polishing, then photoresist with a certain thickness is coated on the surface of the wafer, ultraviolet lithography exposure is adopted, and a III-V group wedge-shaped coupling structure 301 and a III-V group straight waveguide structure 302 glue layer are left after development and fixation; and completely etching the III-V material layer by an inductively coupled plasma etcher (ICP), and cleaning and removing the photoresist to finish the pattern transfer from the photoresist pattern to the III-V material layer.
Based on the silicon nitride micro-ring resonant cavity and the preparation method thereof, the optical path and the working principle of the silicon nitride micro-ring resonant and gyroscope optical waveguide grating coupling chip in the above embodiment are described in detail with reference to the accompanying drawings.
In some embodiments, the period, duty cycle, etch depth, and number of grating periods of the silicon nitride bragg grating coupler are determined based on the diffraction capability of the grating, the directivity of the grating, and the influence of the overlap integral of the grating and the optical field on the grating coupling efficiency.
In connection with the above embodiments, as shown in fig. 2, the basic structure of the grating coupling is a bragg grating structure, which adopts the concept of wave loss to explain the relationship between incident light wave loss and diffracted light wave loss. Incident light is diffracted on the surface of the grating, and in order to realize interference phase lengthening, the diffracted light beam needs to satisfy the formula
Wherein m represents the number of diffraction orders and is an integer; λ is the wavelength in the light propagation space, d is the grating center, θ is the angle of incidence,
is the diffraction angle. In order to obtain a larger coupling efficiency, the period, duty ratio, etching depth and grating period number of the grating coupler are generally changed. For a uniform grating coupler, the factors that affect the coupling efficiency of the grating coupler include three aspects: diffraction power of grating eta1Directivity of grating eta2Overlap integral eta of sum grating and optical field3。
Wherein the diffraction power η of the grating1Is related to the transmittance and reflectance of the grating, specifically:
η1＝1-T-R
T＝t2
R＝r2
the directivity of the grating refers to the distribution ratio of the upward diffracted energy and the downward diffracted energy of the grating, and specifically includes:
and the mode field overlapping integral part of the grating and the optical fiber is obtained by an eigenmode expansion method:
the coupling efficiency of the grating can be obtained:
η＝η1·η2·η3
by optimizing these three parameters, which are closely related to the coupling coefficient, the maximum coupling efficiency can be obtained.
In some embodiments, the coupling distance between the silicon nitride waveguide and the silicon nitride micro-ring resonator is determined according to the set transmission loss of the micro-ring and the length of the resonator.
In combination with the above embodiment, as shown in fig. 2, the straight waveguide 103 and the micro-ring resonator 104 perform optical coupling in a width gradual manner (the distance between the straight waveguide 103 and the micro-ring resonator 104 is gradually reduced), in this embodiment, the structure of the straight waveguide 103 at the coupling connection may be adjusted to be a straight waveguide or a curved waveguide structure according to the curvature of the ring resonator, so as to reduce the coupling mismatch factor and reduce the insertion loss of the evanescent wave coupler. In one example, the radius of the micro-ring resonator 104 is 0.3 cm. The straight waveguide 103 and the micro-ring resonator 104 have an optimal coupling coefficient. After the transmission loss of the micro-ring and the length of the resonant cavity are set, the optimal coupling coefficient can be calculated by means of software, and then the coupling distance corresponding to the coupling coefficient is obtained through simulation software.
Of course, the silicon nitride micro-ring resonator and the size setting of each component in the gyroscope optical waveguide chip in the above embodiments may also be adaptively adjusted according to actual needs, and are not limited to the embodiments shown above.
It should be noted that in the drawings or description, the same drawing reference numerals are used for similar or identical parts. Implementations not depicted or described in the drawings are of a form known to those of ordinary skill in the art. Additionally, while exemplifications of parameters including particular values may be provided herein, it is to be understood that the parameters need not be exactly equal to the respective values, but may be approximated to the respective values within acceptable error margins or design constraints. Directional phrases used in the embodiments, such as "upper," "lower," "front," "rear," "left," "right," and the like, refer only to the orientation of the figure. Accordingly, the directional terminology used is intended to be in the nature of words of description rather than of limitation.
Also, some conventional structures and components may be shown in simplified schematic form in the drawings for the purpose of achieving a neat drawing. In addition, some features in the drawings may be slightly enlarged or changed in scale or size for the purpose of facilitating understanding and viewing of the technical features of the present invention, but this is not intended to limit the present invention. The actual dimensions and specifications of the product manufactured according to the teachings of the present invention may be adjusted according to manufacturing requirements, the nature of the product, and the invention as disclosed below.
In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A hybrid integrated silicon nitride micro-ring resonator, comprising:
a silicon nitride waveguide;
the silicon nitride micro-ring resonant cavity is arranged to form coupling connection with the silicon nitride waveguide;
a wedge-shaped vertical coupler comprising:
the silicon nitride Bragg grating coupler is connected with the silicon nitride waveguide through a wedge-shaped coupler;
the polycrystalline silicon wedge-shaped coupling structure is arranged on the silicon nitride Bragg grating coupler and the wedge-shaped coupler; and
the III-V family wedge-shaped coupling structure is arranged on the polycrystalline silicon wedge-shaped coupling structure;
the III-V waveguide is arranged and connected with the III-V wedge-shaped coupling structure;
the III-V group waveguide is connected with the silicon nitride waveguide through three layers of wedge-shaped vertical couplers, so that the integration of active and passive devices is realized.
2. The hybrid integrated silicon nitride micro-ring resonator of claim 1, further comprising:
a substrate silicon wafer on which a silicon dioxide layer is deposited;
the silicon nitride waveguide, the silicon nitride Bragg grating coupler, the wedge-shaped coupler and the silicon nitride micro-ring resonant cavity form a silicon nitride core layer which is arranged on the silicon dioxide layer.
3. The hybrid integrated silicon nitride micro-ring resonator according to claim 2, wherein the thickness of the silicon dioxide layer is greater than or equal to 2 μ ι η.
4. The hybrid integrated silicon nitride micro-ring resonator according to claim 1, wherein the wedge coupler is a waveguide with a wedge structure, a narrow waveguide end of the waveguide is connected to the silicon nitride waveguide, and a wide waveguide end is matched with the structure size of the silicon nitride bragg grating coupler.
5. The hybrid integrated silicon nitride micro-ring resonator according to claim 1, wherein the thickness of the polysilicon wedge-shaped coupling structure is 400-600 nm.
6. The hybrid integrated silicon nitride micro-ring resonator according to claim 1, wherein the silicon nitride waveguide structure is a rectangular waveguide structure.
7. The hybrid integrated silicon nitride micro-ring resonator according to claim 1, wherein the waveguide structure at the coupling connection between the silicon nitride waveguide and the micro-ring resonator is a straight waveguide or a curved waveguide structure.
8. A method for preparing a hybrid integrated silicon nitride micro-ring resonator, which realizes the preparation of the hybrid integrated silicon nitride micro-ring resonator according to any one of claims 1 to 7, and comprises the following steps:
depositing a silicon nitride layer on the silicon dioxide layer of the substrate silicon wafer;
preparing a silicon nitride waveguide, a silicon nitride Bragg grating coupler, a wedge-shaped coupler and a silicon nitride micro-ring resonant cavity on the silicon nitride layer to obtain a silicon nitride core layer;
depositing a polysilicon layer on the silicon nitride core layer, and preparing a polysilicon wedge-shaped coupling structure on the polysilicon layer;
and bonding a III-V group derivation layer on the polycrystalline silicon layer, and preparing a III-V group wedge-shaped coupling structure and a III-V group waveguide on the III-V group derivation layer.
9. The method according to claim 8, wherein the coupling distance between the silicon nitride waveguide and the silicon nitride micro-ring resonator is determined according to the set micro-ring transmission loss and the resonator length.
10. The method according to claim 8, wherein the period, duty cycle, etching depth and grating period number of the silicon nitride Bragg grating coupler are determined according to the grating diffraction capability, the grating directivity and the grating-to-optical field overlap integral effect on the grating coupling efficiency.
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