CN214375657U - Hybrid integrated photoelectric chip, optical modulator and fiber-optic gyroscope - Google Patents

Abstract

The invention discloses a hybrid integrated photoelectric chip, an optical modulator and a fiber-optic gyroscope, wherein the hybrid integrated photoelectric chip comprises an electro-optic crystal substrate with a linear electro-optic effect and a PLC (programmable logic controller) optical waveguide substrate, and an optical waveguide end face of the electro-optic crystal substrate is connected with an optical waveguide end face of the PLC optical waveguide substrate; the electro-optic crystal substrate with the linear electro-optic effect is formed with a waveguide and a modulation electrode, wherein the waveguide is used for optical wave transmission and phase modulation, and the position of the modulation electrode is matched with that of the waveguide; the PLC optical waveguide substrate is provided with a waveguide for splitting and combining light waves. The hybrid integrated photoelectric chip and the optical modulator based on the hybrid integrated photoelectric chip can effectively reduce the recoupling of asymmetric mode light waves generated at the first Y branch to the second Y branch and the parasitic phase difference formed in the phase modulator in the electro-optic crystal, and are favorable for improving the zero-offset stability of the interference type optical fiber gyroscope.

Description

Hybrid integrated photoelectric chip, optical modulator and fiber-optic gyroscope

Technical Field

The invention relates to the technical field of fiber optic gyroscopes, in particular to a hybrid integrated photoelectric chip and an optical modulator.

Background

The inertial technology is the core technology for inertial navigation, guidance control, positioning and orientation, attitude stabilization and the like of various moving objects, wherein a gyroscope is used as a core component of an inertial measurement system and is used for measuring the angular displacement and the angular velocity of the moving objects, and the gyroscope plays a key role in the performance of the inertial system. The interference type fiber-optic gyroscope based on the Sagnac effect has the advantages of being free of moving parts, large in dynamic range, high in sensitivity, resistant to electromagnetic interference, flexible in structure and the like, and strong in compatibility with optical communication devices, so that batch production can be achieved, and rapid development and wide engineering application are achieved in recent years.

Fig. 1 shows a basic optical path structure of a conventional interference-type fiber optic gyroscope, in which a Sagnac interferometer is a main body and has an anisotropic optical path structure formed by discrete optoelectronic devices such as a laser source, a fiber coupler, a photodetector, a Y-waveguide modulator, and a fiber ring. In order to improve the reliability and the integration level of the interferometric fiber optic gyroscope, a technical scheme of a fiber optic gyroscope based on a double-Y-branch waveguide modulator is provided by those skilled in the art, and the basic optical path structure of the fiber optic gyroscope is shown in fig. 2. The optical wave splitting and beam combining functions of the optical fiber coupler are realized through the waveguide coupler, and the waveguide coupler and the Y waveguide modulator are prepared on the same lithium niobate wafer to form the double-Y branch waveguide modulator, so that the number of optical fiber fusion points of the interference type optical fiber gyroscope and the number of discrete photoelectric components can be effectively reduced, and the integration level and the reliability of the optical fiber gyroscope are further improved.

Although the structure adopting the double-Y-branch waveguide modulator is beneficial to improving the integration level of discrete photoelectric components, as the optical wave forms 3dB light splitting at the first Y branch, half of the optical wave exists in an asymmetric mode instead of a guided wave mode and radiates into the lithium niobate substrate wafer. Further, a part of the asymmetric mode light waves are recoupled into the second Y branch by reflection or refraction at the bottom edge or side edge of the substrate wafer, causing the parasitic light waves with asymmetry to be superposed with the guided-wave mode light waves transmitted on the two transmission arms of the second Y branch to generate a parasitic phase difference. Since the parasitic phase difference is very sensitive to temperature variation, the zero-bias stability of the interference type fiber optic gyroscope is seriously affected.

Therefore, the problem to be solved by the present invention is to reduce the phase difference caused by the parasitic light wave existing in the double Y-branch waveguide modulator at the second Y-branch, and to reduce the influence of the phase difference on the zero-offset stability of the interferometric fiber optic gyroscope.

Disclosure of Invention

A first object of the present invention is to provide a hybrid integrated optical-electrical chip, in which an optical waveguide array including an electro-optical phase modulation function is connected to a dual Y-branch waveguide coupler based on a Planar Lightwave Circuit (PLC), thereby reducing a parasitic phase difference caused by an asymmetric mode lightwave and improving sensing accuracy of an interference-type fiber optic gyroscope based on the hybrid integrated optical-electrical chip.

In order to achieve the first object of the invention, the invention provides a hybrid integrated photoelectric chip, which comprises an electro-optical crystal substrate with a linear electro-optical effect and a PLC optical waveguide substrate, wherein an optical waveguide end face of the electro-optical crystal substrate is connected with an optical waveguide end face of the PLC optical waveguide substrate;

the electro-optic crystal substrate with the linear electro-optic effect is formed with a waveguide and a modulation electrode, wherein the waveguide is used for optical wave transmission and phase modulation, and the position of the modulation electrode is matched with that of the waveguide;

the PLC optical waveguide substrate is provided with a waveguide for splitting and combining optical waves;

the waveguide for light wave transmission is connected with the waveguide for phase modulation through the waveguide for light wave splitting and beam combining functions.

The electro-optic crystal substrate with the linear electro-optic effect adopts one of the following materials: lithium niobate, lithium tantalate, lead lanthanum zirconate titanate, and potassium titanyl phosphate.

The PLC optical waveguide substrate adopts quartz or silica-based silicon dioxide as a substrate material.

The waveguide for light wave transmission and phase modulation and the waveguide for light wave splitting and beam combining function adopt one of the following structures:

a first waveguide structure: the waveguides used for optical wave transmission and phase modulation comprise a first straight waveguide, a second straight waveguide, a third straight waveguide and a fourth straight waveguide;

the waveguide for the light wave splitting and beam combining function comprises a first Y-branch waveguide, a second Y-branch waveguide and an arc waveguide which are arranged side by side, and the first Y-branch waveguide and the second Y-branch waveguide are connected through the arc waveguide;

two arms of the first Y-branch waveguide are respectively connected with the first straight waveguide and the second straight waveguide, and two arms of the second Y-branch waveguide are respectively connected with the third straight waveguide and the fourth straight waveguide;

second waveguide structure: the waveguides used for optical wave transmission and phase modulation comprise a first straight waveguide, a second straight waveguide, a third straight waveguide and a fourth straight waveguide;

the waveguide for the light wave splitting and beam combining function comprises a first Y-branch waveguide and a second Y-branch waveguide, the second Y-branch waveguide comprises two circular arc waveguides, a first branch arm and a second branch arm, two arms of the first Y-branch waveguide are respectively connected with a second straight waveguide and a third straight waveguide, the first Y-branch waveguide is respectively connected with the first branch arm and the second branch arm through the two circular arc waveguides, and the first branch arm and the second branch arm are respectively connected with the first straight waveguide and a fourth straight waveguide.

Wherein, in the first waveguide structure, the structure of the modulation electrode adopts one of the following structures:

a first electrode structure: the modulation electrode comprises a modulation electrode first branch and a modulation electrode second branch, wherein the modulation electrode first branch and the modulation electrode second branch are placed on the upper surface of the electro-optic crystal substrate and are respectively placed on two sides of the third straight waveguide and the fourth straight waveguide;

second electrode structure: the modulation electrode comprises a first modulation electrode branch and a second modulation electrode branch, wherein the first modulation electrode branch and the second modulation electrode branch are arranged on the upper surface of the electro-optic crystal substrate, the first modulation electrode branch is respectively arranged right above the third straight waveguide and the fourth straight waveguide, and the second modulation electrode branch is arranged on two sides of the third straight waveguide and the fourth straight waveguide;

in the second waveguide structure, the structure of the modulation electrode adopts one of the following structures:

third electrode configuration: the modulation electrode comprises a modulation electrode first branch and a modulation electrode second branch, wherein the modulation electrode first branch and the modulation electrode second branch are placed on the upper surface of the electro-optic crystal substrate and are respectively placed on two sides of the first straight waveguide and the fourth straight waveguide;

fourth electrode configuration: the modulation electrode comprises a first modulation electrode branch and a second modulation electrode branch, wherein the first modulation electrode branch and the second modulation electrode branch are arranged on the upper surface of the electro-optic crystal substrate, the first modulation electrode branch is respectively arranged right above the first straight waveguide and the fourth straight waveguide, and the second modulation electrode branch is arranged on two sides of the first straight waveguide and the fourth straight waveguide.

The end face of the PLC optical waveguide substrate is provided with a thin film with a function of reducing light reflection, and the side end face is the end opposite to the end face connected with the electro-optical crystal substrate.

A second object of the present invention is to provide an optical modulator based on the hybrid integrated optoelectronic chip, which includes any one of the above hybrid integrated optoelectronic chip schemes and an optical fiber array connected to the hybrid integrated optoelectronic chip;

and optical fibers are arranged in the optical fiber array, and one ends of the optical fibers are respectively connected with the first straight waveguide, the second straight waveguide, the third straight waveguide and the fourth straight waveguide.

4 optical fibers, namely a first optical fiber, a second optical fiber, a third optical fiber and a fourth optical fiber, are placed in the optical fiber array and are respectively connected with the waveguide in the electro-optic crystal substrate, wherein the first optical fiber, the second optical fiber, the third optical fiber and the fourth optical fiber are polarization maintaining optical fibers or single mode optical fibers.

The optical fiber array is connected with the electro-optical crystal substrate, and the electro-optical crystal substrate is connected with the PLC optical waveguide substrate in an adhesive mode through glue.

A third object of the present invention is to provide a fiber-optic gyroscope based on the optical modulator, including any one of the above optical modulator solutions, and a laser light source, a photodetector, and an optical fiber loop connected to the optical modulator;

the other end of the optical fiber is connected with the laser light source, the photoelectric detector and the optical fiber ring, the polarization maintaining optical fiber is connected with the optical fiber ring, and the polarization maintaining optical fiber or the single mode optical fiber is connected with the laser light source and the photoelectric detector.

Compared with a double-Y-branch waveguide modulator in the prior art, the hybrid integrated photoelectric chip and the optical modulator based on the hybrid integrated photoelectric chip can effectively reduce the recoupling of asymmetric mode light waves generated at the first Y branch to the second Y branch and the parasitic phase difference formed in the phase modulator in the electro-optic crystal, and are beneficial to improving the zero-bias stability of the interference type fiber optic gyroscope.

Drawings

FIG. 1: the optical path structure schematic diagram of the interference type optical fiber gyroscope based on the Y waveguide modulator in the prior art;

FIG. 2: the optical path structure schematic diagram of the interference type fiber-optic gyroscope based on the double Y-branch waveguide modulator in the prior art;

FIG. 3: the invention provides a structural schematic diagram of a first embodiment of a hybrid integrated photoelectric chip;

FIG. 4: the invention provides a schematic diagram of a transmission route of light waves in a hybrid integrated photoelectric chip;

FIG. 5: the transmission route of light waves in a double-Y waveguide modulator chip in the prior art is shown schematically;

FIG. 6: the structure schematic diagram of the optical modulator provided by the invention;

FIG. 7: the invention provides a structural schematic diagram of a second embodiment of a hybrid integrated photoelectric chip;

fig. 8 and 9: the structure of the third embodiment of the hybrid integrated photoelectric chip provided by the invention is shown schematically;

FIG. 10: the optical path structure schematic diagram of the interference type fiber-optic gyroscope based on the optical modulator provided by the invention;

in the figure, the names corresponding to the integrated components provided by the invention are marked as follows: 200. an electro-optic crystal substrate; 1-prior art Y waveguide modulator, 2-prior art double Y branch waveguide modulator, 201, first straight waveguide; 202. a second straight waveguide; 203. a third straight waveguide; 204. a fourth straight waveguide; 211. a modulating electrode first branch; 212. a modulating electrode second branch; 300. a PLC optical waveguide substrate; 301. a first Y-branch waveguide; 302. a second Y-branch waveguide; 301a, a first branch arm of a first Y-branch waveguide; 301b, a second branch arm of the first Y-branch waveguide; 302a, a first branch arm of a second Y-branch waveguide; 302b, a second branch arm of a second Y-branch waveguide; 311. a first circular arc waveguide; 312. a second circular arc waveguide; 313. a third circular waveguide; 321. a film having a function of reducing light reflection; 400. an optical fiber array; 401. a first optical fiber; 402. a second optical fiber; 403. fiber III; 404. fiber four; 411. a first optical fiber port; 412. a second optical fiber port; 413. a third optical fiber port; 414. a fourth optical fiber port; A. an end face where the electro-optical crystal substrate 200 is connected to the optical fiber array 400; B. an end surface of the PLC optical waveguide substrate 300.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that the term "connected" and the words used to express "connected" in this application, such as "connected", "fixed", "hinged", etc., include both the direct connection of one element to another element and the connection of one element to another element through another element.

The specific meaning of the above terms in the present application can be understood by those skilled in the art as the case may be.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Example one

Fig. 3 is a schematic structural diagram of a hybrid integrated optoelectronic chip according to an embodiment of the present invention, which is a top view structure.

Specifically, the hybrid integrated optoelectronic chip provided in this embodiment includes: the electro-optical crystal substrate 200, the PLC optical waveguide substrate 300, the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203, the fourth straight waveguide 204, the modulation electrode first branch 211, the modulation electrode second branch 212, the first Y-branch waveguide 301, the second Y-branch waveguide 302 and the circular arc waveguide 311.

The electro-optical crystal substrate 200 is an optical crystal having a linear electro-optical effect, such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead lanthanum zirconate titanate (PLZT), or potassium titanyl phosphate (KTP).

In a preferred embodiment, lithium niobate is used as a constituent material of the electro-optic crystal substrate 200. Further, the electro-optical crystal substrate 200 is formed of an X-cut or Y-cut lithium niobate crystal.

The first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203, and the fourth straight waveguide 204 are straight strip-shaped optical waveguides, and are all prepared in the electro-optic crystal substrate 200. Taking lithium niobate crystals as an example, the optical waveguides known to those skilled in the art include titanium-diffused waveguides, annealed proton-exchanged waveguides, zinc-diffused waveguides, zinc oxide-diffused waveguides, and the like. The first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203 and the fourth straight waveguide 204 may be selected from any one of the above fabrication techniques, or a combination of several fabrication techniques. Preferably, the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203 and the fourth straight waveguide 204 are all annealed proton-exchanged waveguides. Alternatively, the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203, and the fourth straight waveguide 204 may also be annealed proton exchange waveguides fabricated on a ridge-shaped protruding structure fabricated on the electro-optic crystal substrate 200 by one of the technical means such as dry etching, wet etching, or optical precision cutting.

The modulation electrode first branch 211 and the modulation electrode second branch 212 are disposed on the upper surface of the electro-optic crystal substrate 200 and disposed on two sides of the third straight waveguide 203 and the fourth straight waveguide 204, respectively. An electric field distribution can be formed in the electro-optic crystal substrate 200 by applying an electric signal with a certain amplitude to the modulation electrode first branch 211 and the modulation electrode second branch 212, and the phase of the light wave transmitted in the third straight waveguide 203 and the fourth straight waveguide 204 can be modulated by the linear electro-optic effect thereof.

It should be noted that, as shown in fig. 3, when the modulation electrode first branch 211 is disposed on both sides of the third straight waveguide 203 and the fourth straight waveguide 204, one or two modulation electrode second branches 212 may be disposed therebetween.

The first straight waveguide 201 or the second straight waveguide 202 is only used for transmitting light waves and does not perform phase modulation, so that no modulation electrode is disposed at the first straight waveguide 201 or the second straight waveguide 202, of course, modulation electrodes may be disposed on two sides of the first straight waveguide 201 or the second straight waveguide 202, and no third straight waveguide 203 or the fourth straight waveguide 204 is disposed.

In the present embodiment, the light wave splitting and combining functions of the Y-branch optical waveguide as described in the background art are realized by the first Y-branch waveguide 301 and the second Y-branch waveguide 302 formed in the PLC optical waveguide substrate 300, and the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203, and the fourth straight waveguide 204 formed in the electro-optic crystal substrate 200 are only used for transmission and phase modulation of light waves (the straight waveguides 203 and 204) and do not participate in the light wave splitting or combining action. In addition, since the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203 and the fourth straight waveguide 204 formed in the electro-optic crystal substrate 200 preferably employ annealed proton-exchanged optical waveguides, the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203 and the fourth straight waveguide 204 are also used for filtering the polarization state of the optical wave to obtain highly linearly polarized optical waves, which is well known to those skilled in the art.

The lithium niobate crystal has a large linear electro-optic effect, is an excellent material for manufacturing the optical waveguide phase modulator, and has the remarkable advantages of high modulation rate, low modulation driving voltage and the like. However, the optical waveguide manufactured in the lithium niobate crystal has a high bending loss, so the allowable bending radius of the optical waveguide is large, generally in a few centimeters, and a small bending radius tends to cause a large increase in the bending loss.

Planar Lightwave Circuit (PLC) optical waveguides based on quartz or silica-based silicon dioxide materials do not have excellent electro-optic modulation performance, but are ideal dielectric materials for passive optical transmission. Particularly, the PLC optical waveguide has a low transmission loss on one hand, and also allows a bending radius as small as about 2mm without a large increase in bending loss on the other hand, so that it can be used to fabricate a circular waveguide or an optical waveguide structure with more integrated optical device functions, and the PLC optical waveguide substrate 300 uses quartz or silica-based silicon as a substrate material.

The idea on which the invention is based is therefore that: the optical waveguide phase modulator and the double-Y waveguide coupler are respectively arranged in two substrates made of different materials, and the two Y-branch optical waveguides are connected through the arc waveguide by utilizing the characteristic of low bending loss of the PLC optical waveguide, so that the transmission direction of the asymmetric mode optical wave is opposite to that of the guided wave mode optical wave, and the recoupling of the asymmetric mode optical wave at the second Y branch is reduced.

The PLC optical waveguide substrate 300 may be fabricated using an optical waveguide fabrication process known to those skilled in the art, such as ion diffusion or a semiconductor process.

Specifically, the PLC optical waveguide substrate 300 includes: the PLC optical waveguide substrate 300 includes a first Y-branch waveguide 301, a second Y-branch waveguide 302, and an arc waveguide 311, wherein the first Y-branch waveguide 301 and the second Y-branch waveguide 302 are connected to each other by the arc waveguide 311.

Wherein, two arms of the first Y-branch waveguide 301 formed in the PLC optical waveguide substrate 300 are respectively connected with the first straight waveguide 201 and the second straight waveguide 202 formed in the electro-optical crystal substrate 200, two arms of the second Y-branch waveguide 302 formed in the PLC optical waveguide substrate 300 are respectively connected with the third straight waveguide 203 and the fourth straight waveguide 204 formed in the electro-optical crystal substrate 200, and two arms of the first Y-branch waveguide 301 and two arms of the second Y-branch waveguide 302 are disposed on the same side of the PLC optical waveguide substrate 300.

Since the electro-optical crystal substrate 200 and the PLC optical waveguide substrate 300 are two independent crystal substrates, the connection between the substrate 200 and the substrate 300 is achieved by:

first, each straight waveguide formed in the electro-optic crystal substrate 200 is aligned with two Y-branch waveguides formed in the PLC optical waveguide substrate 300 using a six-dimensional optical fiber fine adjustment jig; then, using ultraviolet glue to bond the end surfaces of the two substrates; and finally, using an ultraviolet lamp to expose and cure the ultraviolet glue to complete the connection of the two substrates.

The transmission route of light waves in the hybrid integrated optoelectronic chip is described below with reference to fig. 4 and 5. Referring to fig. 4 and fig. 5, fig. 4 is a schematic diagram of a transmission path of a light wave in a hybrid integrated optoelectronic chip provided by the present invention, and fig. 5 is a schematic diagram of a transmission path of a light wave in a conventional dual Y-branch waveguide modulator chip.

Specifically, the solid arrow at the lower left of fig. 4 indicates the incident light wave from the laser light source, and the incident light wave first enters the first straight waveguide 201 in the electro-optical crystal substrate 200, and the high polarization characteristic of the first straight waveguide 201 can filter the polarization state of the incident light wave and obtain highly linearly polarized light.

Further, the light wave enters the first branch arm 301a of the first Y-branch waveguide 301 in the PLC optical waveguide substrate 300 through the transmission of the first straight waveguide 201, the light wave transmitted in the first Y-branch waveguide 301 is split by 3dB at the Y-branch, wherein half of the light wave enters the circular arc waveguide 311 in a guided wave mode for continuous transmission, and the other half of the light wave forms an asymmetric mode and is radiated into the PLC optical waveguide substrate 300. In fig. 4 and 5, solid arrows indicate transmission paths of guided-mode light waves, and dashed arrows indicate transmission paths of asymmetric-mode light waves.

Further, the guided-wave mode light wave transmitted in the optical waveguide reaches the second Y-branch waveguide 302 arranged side by side with the first Y-branch waveguide 301 by passing through the circular arc waveguide 311, and is split into two light waves at the Y-branch, which enter the first branch arm 302a of the second Y-branch waveguide 302 and enter the second branch arm 302b of the second Y-branch waveguide for transmission, respectively.

Further, the two light waves enter the third straight waveguide 203 and the fourth straight waveguide 204 in the electro-optical crystal substrate 200 through the transmission of the second Y-branch waveguide first branch arm 302a and the second Y-branch waveguide second branch arm 302b of the second Y-branch waveguide 302 in the PLC optical waveguide substrate 300, respectively, and modulate the phase of the light wave transmitted in the third straight waveguide 203 and the fourth straight waveguide 204 through the electric field formed between the modulation electrode first branch 211 and the modulation electrode second branch 212. The two light waves after phase modulation finally exit from the hybrid integrated optoelectronic chip from the third straight waveguide 203 and the fourth straight waveguide 204.

As is apparent from comparing fig. 4 and fig. 5, the hybrid integrated optoelectronic chip provided by the present invention first places the dual Y-branch optical waveguide in the PLC optical waveguide substrate 300, and further connects the two Y-branch optical waveguides 301 and 302 through the circular waveguide 311 by utilizing the characteristic of small bending radius of the PLC optical waveguide, so that the two Y-branch optical waveguides 301 and 302 are placed side by side in the PLC optical waveguide substrate 300. However, this placement is not achievable in existing lithium niobate optical waveguide modulators, particularly existing dual Y-branch waveguide modulators.

In the conventional dual Y-branch waveguide modulator shown in fig. 5, the two Y-branch optical waveguides are fabricated in the same lithium niobate wafer on the one hand, and are disposed on both sides of the lithium niobate wafer on the other hand. Therefore, in the conventional dual Y-branch waveguide modulator, the asymmetric mode light wave (indicated by a dashed arrow in fig. 5) formed at the first Y-branch will continue to be transmitted forward along the original light wave transmission direction, and thus, the asymmetric mode light wave will be reflected and refracted by the bottom edge and the side edge of the lithium niobate wafer, so that a part of the asymmetric mode light wave will be recoupled on the second Y-branch, and will be superimposed on the light wave transmitted in the two arms of the second Y-branch to further form a parasitic phase difference, which will greatly affect the zero offset stability of the interferometric fiber optic gyroscope.

As can be seen from fig. 4, in the hybrid integrated optical-electrical chip provided by the present invention, the asymmetric mode light wave (indicated by the dashed arrow in fig. 4) formed at the first Y-branch waveguide 301 continues to transmit along the transmission direction of the original light wave until reaching the end face B of the PLC optical waveguide substrate 300. In addition, the transmission of the guided-wave mode light wave continuously transmitted in the PLC optical waveguide through the circular arc waveguide 311 turns the transmission route of the light wave by 180 °, so that the transmission direction of the light wave and the asymmetric mode light wave is also 180 ° reversed, thereby effectively reducing the recoupling of the asymmetric mode light wave to the first branch arm 302a of the second Y-branch waveguide and the second branch arm 302b of the second Y-branch waveguide 302, and further effectively reducing the generation of the parasitic phase difference.

In order to further reduce the existence of the asymmetric mode light wave in the PLC optical waveguide substrate 300, a film 321 with a function of reducing light reflection, such as a metal film or an anti-reflection dielectric film (anti-reflection dielectric film), may be deposited on the end face B, and the reflection of the asymmetric mode light wave at the end face B is reduced through the absorption effect of the metal film or the enhancement effect of the anti-reflection dielectric film on the light wave transmission.

As shown in fig. 6, based on the hybrid integrated optoelectronic chip, the present embodiment provides an optical modulator, which includes: the hybrid integrated optoelectronic chip, the optical fiber array 400, and the optical fiber array 400 is also the optical fiber array.

In the optical modulator provided in this embodiment, since the input and output of the optical wave are located at the same end of the hybrid integrated optical-electrical chip, i.e. the end face a of the electro-optical crystal substrate 200, the form of the optical Fiber Array (Fiber Array) is selected to perform coupling and bonding between the optical Fiber and each optical waveguide of the hybrid integrated optical-electrical chip.

The optical fiber array 400 is a crystal block made of any one of materials such as quartz, silicon, glass, and lithium niobate, and a crystal block made of quartz is preferably used. The optical fiber array 400 has 4 optical fibers, i.e., a first optical fiber 401, a second optical fiber 402, a third optical fiber 403, and a fourth optical fiber 404. And the third optical fiber 403 and the fourth optical fiber 404 are polarization-maintaining optical fibers and are used for being connected with a polarization-maintaining optical fiber ring in the optical fiber gyroscope through optical fiber fusion. The first optical fiber 401 and the second optical fiber 402 may be polarization maintaining optical fibers or single mode optical fibers, and are respectively used for connecting with a laser light source or a photodetector through optical fiber fusion. The optical fiber array 400 with optical fibers includes 4 optical fiber ports, i.e., a first optical fiber port 411, a second optical fiber port 412, a third optical fiber port 413, and a fourth optical fiber port 414, which are respectively connected to the first straight waveguide 201, the second straight waveguide 202, the third straight waveguide 203, and the fourth straight waveguide 204 in the electro-optic crystal substrate 200.

The connection between the fiber array 400 and the end face a of the electro-optic crystal substrate 200 is also bonded by using ultraviolet curing glue and further cured by exposing the glue by using an ultraviolet lamp.

In addition, the invention provides a fiber-optic gyroscope, in particular an interference fiber-optic gyroscope, based on the optical modulator. As shown in fig. 10, there is provided an optical path structure of an interference type fiber optic gyroscope, including: laser light source 501, photodetector 502, optical fiber loop 503. The laser light source 501 is connected with the first optical fiber 401 (or the second optical fiber 402) through an optical fiber, the photodetector 502 is connected with the second optical fiber 402 (or the first optical fiber 401) through an optical fiber, and two optical fibers of the optical fiber loop 503 are respectively connected with the third optical fiber 403 and the fourth optical fiber 404.

It should be noted that, in the following description,

the light wave emitted from the laser light source 501 passes through the first optical fiber 401, the first straight waveguide 201, the transmission of the branch arm 301a in the first Y branch and the 180 ° rotation of the circular arc waveguide 311 in sequence, is divided into two light waves in the second Y branch 302, and enters the optical fiber loop 503 along the transmission of the third straight waveguide 203, the third optical fiber 403, the fourth straight waveguide 204 and the fourth optical fiber 404, respectively, as shown in fig. 10, the two light waves point to the left side in the direction of the arrow in front of the optical fiber loop 503, and is called as "forward light wave". The light wave entering the optical fiber loop 503 along the optical fiber three 403 is transmitted in the optical fiber loop 503 in a clockwise direction and enters the optical fiber four 404, and the light wave entering the optical fiber loop 503 along the optical fiber four 404 is transmitted in the optical fiber loop 503 in a counterclockwise direction and enters the optical fiber three 403, as shown in fig. 10, two light waves pointing to the right in the direction of the arrow in front of the optical fiber loop 503 are called as "reverse light waves".

The two "reverse light waves" are transmitted through the third 403 and the third 203 optical fibers and the fourth 404 and the fourth 204 optical fibers, respectively, and are combined at the second Y branch 302. The combined optical wave reaches the first Y branch 301 through 180 ° rotation of the circular waveguide 311, and a part of the optical wave is transmitted along the branch arm 301b, the second straight waveguide 202, the second optical fiber 402 through the splitting of the first Y branch 301, and reaches the photodetector 502.

When the interference type fiber-optic gyroscope rotates along the rotating shaft of the optical fiber loop, the phases of the two beams of 'reverse light waves' transmitted in the optical fiber loop can be changed respectively, and then the amplitudes of the combined light waves formed by the two beams of 'reverse light waves' at the second Y branch 302 can be changed correspondingly, and finally the output electric signal of the photoelectric detector is caused to change. By applying electrical signals of appropriate magnitude to the modulation electrode branches 201 and 202, the angular velocity information of the fiber optic gyroscope can be demodulated.

Compared with the existing double-Y-branch waveguide coupler which needs to carry out optical fiber coupling for four times, the optical modulator provided by the invention only needs to carry out optical coupling for two times, namely the coupling between the optical fiber array and each straight waveguide of the electro-optic crystal substrate 200 and the coupling between each straight waveguide of the electro-optic crystal substrate 200 and two Y-branch optical waveguides in the PLC optical waveguide substrate 300, so that the optical fiber coupling for two times is reduced, and the sensing precision, the reliability and the convenient operation degree of the interference type optical fiber gyroscope system are improved.

Example two

Fig. 7 shows a second embodiment of the present invention.

In this embodiment, the placement of the modulation electrode and the structure of the second Y branch are both changed:

the second modulation electrode first branch 211 and the modulation electrode second branch 212 are respectively disposed at two sides of the first straight waveguide 201 and the fourth straight waveguide 204, and are used for modulating the phase of the optical wave transmitted in the first straight waveguide 201 and the fourth straight waveguide 204. The second straight waveguide 202 or the third straight waveguide 203 is not provided with a modulation electrode and is only used for transmitting light waves, for example, the second straight waveguide 202 is connected with a laser light source and is used for introducing incident light waves, and the third straight waveguide 203 is connected with a photodetector and is used for introducing light waves into the photodetector for detection.

An incident light wave from the laser light source enters the electro-optical crystal substrate 200 via the second straight waveguide 202, and further enters the branch arm 301a of the first Y-branch 301 in the PLC optical waveguide substrate 300 through the second straight waveguide 202.

The second Y-branch 302 in this embodiment is composed of:

two circular arc waveguides 312, 313, a first branch arm 302a of a second Y-branch waveguide, and a second branch arm 302b of a second Y-branch waveguide. Unlike the first embodiment, the second Y-branch 302 of the present embodiment is composed of two circular arc waveguides 312 and 313, and is connected to the first branch arm 302a of the second Y-branch waveguide and the second branch arm 302b of the second Y-branch waveguide, respectively. Therefore, the light wave from the first Y-branch 301 is first split into two light waves at the second Y-branch 302, and a 180 ° turn of the light wave transmission direction is achieved by clockwise transmission through the circular arc waveguide 312 and counterclockwise transmission through the circular arc waveguide 313, respectively. Further, the two light waves are transmitted through the first branch arm 302a of the second Y-branch waveguide and the second branch arm 302b of the second Y-branch waveguide, respectively, and enter the first straight waveguide 201 and the fourth straight waveguide 204 in the electro-optical crystal substrate 200. The optical waves are transmitted in the same direction in the first branch arm 302a of the second Y-branch waveguide, the second branch arm 302b of the second Y-branch waveguide, and the first straight waveguide 201 and the fourth straight waveguide 204. The optical wave transmission path is shown by the solid arrows in fig. 5.

Similarly, in the optical modulator of the hybrid integrated optical-electrical chip according to the embodiment, the second optical fiber 402 connected to the second straight waveguide 202 is connected to the laser light source, the third optical fiber 403 connected to the third straight waveguide 203 is connected to the photodetector, and the third optical fiber 403 and the fourth optical fiber 404 connected to the first straight waveguide 201 and the fourth straight waveguide 204 are connected to the optical fiber loop in the optical fiber gyroscope.

EXAMPLE III

As shown in fig. 8 and 9, a third embodiment of the present invention is shown.

In the present embodiment, Z-cut lithium niobate crystal is used as the electro-optical crystal substrate 200. In order to utilize the maximum electro-optic coefficient r33 of Z-cut lithium niobate crystal, one branch of the modulation electrode needs to be placed right above the optical waveguide, and the other branch is placed at one side of the branch of the modulation electrode. In fig. 8, the modulation electrode first branch 211 is placed right above the third straight waveguide 203 and the fourth straight waveguide 204, one modulation electrode second branch 212 is placed between the third straight waveguide 203 and the fourth straight waveguide 204, or two modulation electrode second branches 212 may be placed, and of course, the modulation electrode second branch 212 may also be placed on the other side of the third straight waveguide 203 and the fourth straight waveguide 204, respectively.

In fig. 9, the modulating electrode first branch 211 is placed directly above the first straight waveguide 201 and the fourth straight waveguide 204. The modulation electrode second branch 212 is placed at the side of the modulation electrode first branch 211 for forming an electric field distribution containing a component in the vertical direction in the electro-optical crystal substrate 200.

In order to reduce the absorption of light energy of the modulation electrode, especially the modulation electrode branches disposed right above the optical waveguide, to the optical waveguide, a buffer layer film may be disposed on the upper surface of the electro-optical crystal substrate 200 to separate the optical waveguide and the modulation electrode branches right above the optical waveguide. The buffer layer film may be made of a non-metal material such as silicon oxide, silicon nitride, or aluminum oxide.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A hybrid integrated photoelectric chip is characterized in that,

the optical waveguide structure comprises an electro-optic crystal substrate with a linear electro-optic effect and a PLC optical waveguide substrate, wherein the optical waveguide end face of the electro-optic crystal substrate is connected with the optical waveguide end face of the PLC optical waveguide substrate;

the electro-optic crystal substrate with the linear electro-optic effect is formed with a waveguide and a modulation electrode, wherein the waveguide is used for optical wave transmission and phase modulation, and the position of the modulation electrode is matched with that of the waveguide;

the PLC optical waveguide substrate is provided with a waveguide for splitting and combining optical waves;

the waveguide for light wave transmission is connected with the waveguide for phase modulation through the waveguide for light wave splitting and beam combining functions.

2. The hybrid integrated optoelectronic chip of claim 1,

the electro-optic crystal substrate with the linear electro-optic effect adopts one of the following materials: lithium niobate, lithium tantalate, lead lanthanum zirconate titanate, and potassium titanyl phosphate.

3. The hybrid integrated optoelectronic chip of claim 1,

the PLC optical waveguide substrate adopts quartz or silica-based silicon dioxide as a substrate material.

4. The hybrid integrated optoelectronic chip of any one of claims 1-3,

the structure of the waveguide for light wave transmission and phase modulation and the waveguide for light wave splitting and beam combining functions adopts one of the following structures:

a first waveguide structure: the waveguides used for optical wave transmission and phase modulation comprise a first straight waveguide, a second straight waveguide, a third straight waveguide and a fourth straight waveguide;

the waveguide for the light wave splitting and beam combining function comprises a first Y-branch waveguide, a second Y-branch waveguide and an arc waveguide which are arranged side by side, and the first Y-branch waveguide and the second Y-branch waveguide are connected through the arc waveguide;

two arms of the first Y-branch waveguide are respectively connected with the first straight waveguide and the second straight waveguide, and two arms of the second Y-branch waveguide are respectively connected with the third straight waveguide and the fourth straight waveguide;

second waveguide structure: the waveguides used for optical wave transmission and phase modulation comprise a first straight waveguide, a second straight waveguide, a third straight waveguide and a fourth straight waveguide;

the waveguide for the light wave splitting and beam combining function comprises a first Y-branch waveguide and a second Y-branch waveguide, the second Y-branch waveguide comprises two circular arc waveguides, a first branch arm and a second branch arm, two arms of the first Y-branch waveguide are respectively connected with a second straight waveguide and a third straight waveguide, the first Y-branch waveguide is respectively connected with the first branch arm and the second branch arm through the two circular arc waveguides, and the first branch arm and the second branch arm are respectively connected with the first straight waveguide and a fourth straight waveguide.

5. The hybrid integrated optoelectronic chip of claim 4,

in the first waveguide structure, the structure of the modulation electrode adopts one of the following structures:

a first electrode structure: the modulation electrode comprises a modulation electrode first branch and a modulation electrode second branch, wherein the modulation electrode first branch and the modulation electrode second branch are placed on the upper surface of the electro-optic crystal substrate and are respectively placed on two sides of the third straight waveguide and the fourth straight waveguide;

second electrode structure: the modulation electrode comprises a first modulation electrode branch and a second modulation electrode branch, wherein the first modulation electrode branch and the second modulation electrode branch are arranged on the upper surface of the electro-optic crystal substrate, the first modulation electrode branch is respectively arranged right above the third straight waveguide and the fourth straight waveguide, and the second modulation electrode branch is arranged on two sides of the third straight waveguide and the fourth straight waveguide;

in the second waveguide structure, the structure of the modulation electrode adopts one of the following structures:

third electrode configuration: the modulation electrode comprises a modulation electrode first branch and a modulation electrode second branch, wherein the modulation electrode first branch and the modulation electrode second branch are placed on the upper surface of the electro-optic crystal substrate and are respectively placed on two sides of the first straight waveguide and the fourth straight waveguide;

fourth electrode configuration: the modulation electrode comprises a first modulation electrode branch and a second modulation electrode branch, wherein the first modulation electrode branch and the second modulation electrode branch are arranged on the upper surface of the electro-optic crystal substrate, the first modulation electrode branch is respectively arranged right above the first straight waveguide and the fourth straight waveguide, and the second modulation electrode branch is arranged on two sides of the first straight waveguide and the fourth straight waveguide.

6. The hybrid integrated optoelectronic chip of claim 5,

and a film with a function of reducing light reflection is arranged on the end face of the PLC optical waveguide substrate, and the side end face is the end opposite to the end face connected with the electro-optical crystal substrate.

7. An optical modulator comprising a hybrid integrated optoelectronic chip according to any one of claims 1 to 6 and an array of optical fibers connected to the hybrid integrated optoelectronic chip;

and optical fibers are arranged in the optical fiber array, and one ends of the optical fibers are respectively connected with the first straight waveguide, the second straight waveguide, the third straight waveguide and the fourth straight waveguide.

8. The light modulator of claim 7,

4 optical fibers, namely a first optical fiber, a second optical fiber, a third optical fiber and a fourth optical fiber, are arranged in the optical fiber array and are respectively connected with the waveguide in the electro-optic crystal substrate,

the first optical fiber, the second optical fiber, the third optical fiber and the fourth optical fiber are polarization maintaining optical fibers or single mode optical fibers.

9. The light modulator of claim 8,

the optical fiber array is connected with the electro-optic crystal substrate, and the electro-optic crystal substrate is connected with the PLC optical waveguide substrate in an adhesive mode through glue.

10. A fiber optic gyroscope comprising the optical modulator of any of claims 7-9 and a laser light source, photodetector and fiber optic loop connected to the optical modulator;

the other end of the optical fiber is connected with the laser light source, the photoelectric detector and the optical fiber ring, the polarization maintaining optical fiber is connected with the optical fiber ring, and the polarization maintaining optical fiber or the single mode optical fiber is connected with the laser light source and the photoelectric detector.

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