An optical transceiver integrated module with relative intensity noise suppression for fiber optic gyroscope

Abstract

The present invention discloses an optical transceiver integrated module with relative intensity noise suppression for a fiber optic gyroscope (FOG). The module comprises a pump source module, an erbium-doped fiber, and a receiver module. The pump source module and the receiver module are connected via the erbium-doped fiber. The waveguide wavelength division multiplexer in the pump source module comprises three ports: left-side port 1 is axially coupled to a laser pump source core, left-side port 2 is connected to a first Faraday reflector, and right-side port 3 is connected to a first erbium-doped fiber terminal of the erbium-doped fiber. The second erbium-doped fiber terminal of the erbium-doped fiber in the receiver module is axially coupled to a polarization-maintaining filter isolator. The 50:50 polarization-maintaining waveguide coupler comprises four ports: the other end of the polarization-maintaining filter isolator is connected to input port 1, input port 2 is connected to a detector, output port 1 is connected to a pigtail, and output port 2 is connected to a second Faraday reflector. The optical transceiver integrated module provides a reliable technical approach for the integration and miniaturization of high-precision FOGs, reduces optical path loss, and effectively improves the signal-to-noise ratio.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices and relates to an optical transceiver integrated module with relative intensity noise suppression for high-precision fiber optic gyroscopes. The module is used for integrating an ASE light source with intensity noise suppression with a detector in the field of high-precision fiber optic gyroscopes, and for the integration and coupling packaging between the ASE light source, the detector and the pigtail. Background Art

[0002] Fiber optic gyroscopes (FOGs) are angular velocity sensors based on the Sagnac effect and are widely used in inertial navigation systems. With the continuous development of the inertial navigation field, the requirements for angular velocity sensing accuracy are also increasing. Because optical fiber has very low transmission loss at 1550nm, it is suitable for long-distance transmission or sensing. High-precision FOGs generally use a 1550nm amplified spontaneous emission (ASE) light source based on erbium-doped fiber. This broad-spectrum light source offers advantages such as high wavelength stability and high output power, making it suitable for improving the gyro's zero-bias stability and scale factor stability. However, light intensity fluctuations caused by the beat frequency of different frequency components in the broad-spectrum light source affect the output of the ASE light source. As the optical power increases, the output intensity fluctuation increases. The relative intensity noise (RIN) of the light source is generally defined as the ratio of the intensity fluctuation to the average optical power. In the signal detection process of fiber optic gyroscope, when the optical power reaching the detector exceeds tens of microwatts, the signal-to-noise ratio will no longer increase with the increase of light source power, and RIN becomes the main noise that limits the detection accuracy. Therefore, relevant RIN suppression methods have been developed. The traditional intensity noise suppression ASE solution has the disadvantages of too dispersed devices and too large volume of the entire light source module. Its principle structure is as follows: Figure 2 (a) shows the structure of the fiber pigtail and the melting point. Furthermore, the presence of pigtails and melting point leads to reliability issues and additional errors caused by melting point reflections. Therefore, an effective integration solution is needed to integrate modular components into a whole.

[0003] In order to realize the integration of optical transceiver modules in high-precision fiber optic gyroscopes and reduce the volume size, designing a feasible optical path scheme and structural layout of the optical transceiver modules is the key to solving the problem. The present invention proposes an integration method of a fiber optic gyroscope relative intensity noise suppression ASE light source transceiver module, which is used to reduce the size and weight of the optical transceiver modules in high-precision fiber optic gyroscopes, and has far-reaching significance for the lightweight and miniaturization of high-precision fiber optic gyroscopes. Summary of the Invention

[0004] The present invention aims to achieve the integration of an intensity noise suppression ASE light source and detector for use in a high-precision fiber optic gyroscope. Specifically, an integrated solution based on a waveguide wavelength division multiplexer (WDM) and a waveguide coupler is proposed. The present invention employs the following technical solutions:

[0005] An optical transceiver integrated module with relative intensity noise suppression for a fiber optic gyroscope comprises: a pump source module, an erbium-doped optical fiber, and a receiving module, wherein the pump source module and the receiving module are connected via the erbium-doped optical fiber;

[0006] The pump source module includes a laser pump source, a waveguide wavelength division multiplexer, and a first Faraday reflector. The waveguide wavelength division multiplexer includes three ports, a left port 1 is axially coupled to the laser pump source tube core, a left port 2 is connected to the first Faraday reflector, and a right port is connected to the first erbium-doped fiber terminal of the erbium-doped fiber;

[0007] The receiving module includes a polarization-maintaining filter isolator, a 50:50 polarization-maintaining waveguide coupler, a second Faraday reflector, a detector, and a pigtail. The second erbium-doped fiber terminal of the erbium-doped fiber is axially coupled to the polarization-maintaining filter isolator. The 50:50 polarization-maintaining waveguide coupler includes two input ports and two output ports, wherein the other end of the polarization-maintaining filter isolator is connected to input port 1, input port 2 is connected to the detector, output port 1 is connected to the pigtail, and output port 2 is connected to the second Faraday reflector.

[0008] Furthermore, the first Faraday reflector includes a first Faraday rotator crystal, a total reflection filter film, and a first tubular magnet; the left side port 2 of the waveguide wavelength division multiplexer is connected to the first Faraday rotator crystal, and the end surface of the first Faraday rotator crystal opposite to the end surface connected to the left side port 2 is coated with a total reflection filter film; the first Faraday rotator crystal is located inside the first tubular magnet and can rotate along the first tubular magnet;

[0009] The second Faraday reflector includes a second Faraday rotator crystal, a 2% reflection filter film, and a second tubular magnet. The second output port of the polarization-maintaining filter isolator is connected to the second Faraday rotator crystal. The end face of the second Faraday rotator crystal opposite to the end face connected to the second output port is coated with a 2% reflection filter film. The second Faraday rotator crystal is located inside the second tubular magnet and can rotate along the second tubular magnet.

[0010] Furthermore, in the pump source module, the pump light is transmitted to the erbium-doped fiber through a waveguide wavelength division multiplexer. The erbium-doped fiber generates spontaneous radiation under the action of the pump light. The radiated light of the erbium-doped fiber is transmitted in both forward and reverse directions. Among them, the reverse radiated light is reversely transmitted through the waveguide wavelength division multiplexer and coupled to the first Faraday reflector. After being reflected by the first Faraday reflector, it returns to the erbium-doped fiber again and is radiated and output through the second erbium-doped fiber terminal of the erbium-doped fiber.

[0011] Furthermore, in the receiving module, the forward radiation light of the erbium-doped optical fiber is coupled into the 50:50 polarization-maintaining waveguide coupler through the polarization-maintaining filter isolator, and is coupled into the pigtail through output port one and transmitted to the second Faraday reflector through output port two. The light coupled into output port one is output through the pigtail, i.e., the output light of the integrated module; the light from output port two is rotated in polarization state and reflected by the second Faraday reflector, becoming backward-transmitted light with a polarization state rotated by 90°. The backward-transmitted light and the external return light input in reverse through the pigtail are again reversely transmitted through the 50:50 polarization-maintaining waveguide coupler and coupled to input port two, and detected by the detector.

[0012] Furthermore, the pump source module, erbium-doped fiber and receiving module are encapsulated in the same thin cylindrical structure, the erbium-doped fiber is looped in the groove on the inner wall of the thin cylindrical structure, and the pigtail is led out from the side wall hole of the thin cylindrical structure along the tangential direction.

[0013] Furthermore, the pigtail includes a metallized fiber segment, which is welded to the sidewall hole of the thin cylindrical structural member; the position of the metallized fiber segment in the pigtail is determined by the distance between the receiving module and the sidewall hole of the thin cylindrical structural member.

[0014] The advantages and positive effects of the present invention are:

[0015] (1) The structural scheme adopted in the present invention, “an optical transceiver integrated module with relative intensity noise suppression for high-precision fiber optic gyroscope”, is universal: the erbium-doped optical fiber is separated from the two integrated modules, the pump source module and the receiver module, so that the length of the erbium fiber can be adjusted easily and different erbium fiber lengths can be designed according to different power and wavelength stability requirements; the pump module of the ASE light source, the intensity noise suppression structure and the detector module are integrated separately, which provides a reliable technical approach for the integration and miniaturization of the ASE light source module and the detector module of the high-precision fiber gyroscope.

[0016] (2) The present invention, "an optical transceiver integrated module with relative intensity noise suppression for a high-precision fiber optic gyroscope", adopts waveguide WDM and waveguide couplers to replace the fused-tapered optical fiber devices in the traditional separation component solution, to achieve light beam splitting and coupling, greatly improving the integration of the optical transceiver module, while avoiding the polarization crosstalk or reflected secondary wave interference that may exist in the pigtail fusion point.

[0017] (3) The present invention, “an optical transceiver integrated module with relative intensity noise suppression for high-precision optical fiber gyroscope”, while focusing on the integration of the optical path, adopts waveguide WDM to replace the fused-taper WDM in the traditional ASE light source, reducing the optical path loss by 50%, which helps to improve the signal-to-noise ratio of the high-precision optical gyroscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the principle structure diagram of the fiber optic gyroscope. Figure 1 (a) Fiber optic gyroscope structure without intensity noise suppression; Figure 1 (b) Fiber optic gyroscope structure including intensity noise suppression; Figure 1 (c) is a fiber optic gyroscope scheme that suppresses intensity noise using a Faraday reflector.

[0019] Figure 2 This is the optical path structure diagram of the intensity noise suppression ASE light source and receiving (detector) module. Figure 2 (a) is a traditional separated component solution, in which the components in the optical transceiver module are separated from each other and connected to each other through pigtail fusion; Figure 2 (b) The pump source part and the intensity noise suppression and light receiving part of the intensity noise suppression ASE light source transceiver module are integrated into an integrated optical path structure; the integration of the pump source module 22 and the receiving module 23 is achieved through an axis coupling system.

[0020] Figure 3 It is a three-dimensional schematic diagram of the integrated structure of the designed relative intensity noise suppression ASE light source transceiver module. Figure 3 (a) is the integrated structure of the pump source module; Figure 3 (b) is a receiving module integrated structure; the pump source module 22 and the receiving module 23 are connected through two terminals 41 and 42 of the erbium-doped optical fiber 4.

[0021] Figure 4 This is a schematic diagram of the principle of Faraday rotation effect.

[0022] Figure 5 This is a schematic diagram of the integrated structure of the designed relative intensity noise suppression ASE light source transceiver module, in which the opening on the side wall of the tube shell of the pigtail terminal 21 module realizes interaction with the external light path.

[0023] Figure 6This is a partially enlarged schematic diagram of the polarization-maintaining fiber pigtail terminal 21. The polarization-maintaining fiber is fixed in a silica U-shaped groove, and the end face is cut and polished to meet the requirements. The polarization-maintaining fiber pigtail terminal 21 is then axially coupled to the waveguide coupler 18. In order to hermetically seal the entire module, the section of optical fiber after the pigtail terminal needs to be metallized and then welded to the shell.

[0024] In the figure: 1-980 pump source; 2-fused tapered WDM; 3-Faraday filter reflector; 4-erbium-doped fiber; 5-filter isolator; 6-50:50 polarization-maintaining coupler; 7-99:1 polarization-maintaining coupler; 8-detector; 9-99% port of coupler 7; 10-1% port of coupler 7; 11-12-pigtail terminal; 13-polarization-maintaining pigtail; 14-laser pump source; 15-waveguide WDM; 16-first Faraday reflector; 17-filter isolator; 18-50:50 polarization-maintaining waveguide coupler; 19-first Two Faraday reflectors; 20-detector tube core; 21-polarization-maintaining fiber pigtail terminal; 22-pump source module; 23-receiving module; 24-U-shaped groove; 25-polarization-maintaining fiber; 26-metallized fiber segment; 161-first Faraday rotator crystal; 162-total reflection filter membrane; 163-first tubular magnet; 41-first erbium-doped fiber terminal; 42-second erbium-doped fiber terminal; 191-second Faraday rotator crystal; 192-2% reflection filter membrane; 193-second tubular magnet; 271-light source heat sink; 272-277-companion plates. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings.

[0026] Figure 1 The figure shows the principle structure of fiber optic gyroscope, where Figure 1 (a) is the basic optical path structure of a traditional fiber optic gyroscope. Figure 1 (b) shows the optical path structure of a traditional high-precision fiber optic gyroscope with intensity noise suppression. As can be seen from the figure, the traditional fiber optic gyroscope intensity noise suppression scheme has many separate components, resulting in a large overall volume and many fiber pigtails and fusion points. Figure 1 (c) is a new type of high-precision fiber gyroscope structure that uses a Faraday reflector to suppress intensity noise. The present invention proposes an integrated solution for the miniaturization and integration of the ASE light source and detector with intensity noise suppression in the above-mentioned high-precision fiber gyroscope structure.

[0027] Specifically, the present invention reduces the volume and weight of the optical transceiver module composed of the ASE light source, the intensity noise suppression optical path, and the detector, while abolishing the method of connecting the traditional separation devices through fiber pigtail fusion splicing, reducing the nonlinear error introduced by environmental factors on the optical fiber characteristics and the error introduced by backscattering at the melting point of the optical fiber. Figure 2 Figure (a) shows the optical path structure of an ASE light source transceiver module with intensity noise suppression using traditional discrete components. Typically, the 980 pump source 1 and the erbium-doped fiber 4 in the ASE light source are connected via a fused-tapered WDM 2. Due to the principle of dual-fiber fused-tapering, there is a 50% theoretical optical energy loss. Furthermore, the traditional intensity noise suppression scheme uses a 90° orthogonally fused polarization-maintaining pigtail as the reference light input, and achieves intensity matching with the signal light through a 99:1 polarization-maintaining coupler 7 (signal light 99%, reference light 1%). This splicing process is very prone to introducing errors. Figure 2 (b) shows the integrated optical path structure of the optical transceiver module designed in the present invention. This invention utilizes a waveguide-type WDM 15 to replace the fused-taper WDM 2 in conventional ASE light sources. This facilitates direct on-axis coupling with the laser pump source 14 and Faraday reflector (FRM) 16 while avoiding the 50% optical energy loss found in conventional solutions. Furthermore, the designed intensity noise suppression ASE light source transceiver module features a 90° polarization-rotated FRM 19, providing a reference optical path for intensity noise suppression. The reflectivity of the FRM 19's reflective coating is controlled to approximately 2%, and the FRM 19 is then coupled to the signal optical path via a 50:50 polarization-maintaining waveguide coupler 18, achieving the same effect as a 99:1 polarization-maintaining coupler 7. Furthermore, the 99:1 polarization-maintaining coupler 7 and its 90° cross-splice of the polarization-maintaining pigtail at its 1% port 10, as found in conventional intensity noise suppression solutions, are eliminated. This eliminates the polarization-cross coupling between the pigtail terminals 11 and 12 required in conventional optical path solutions, reducing the complexity of manual operation.

[0028] Furthermore, the present invention integrates a pump source module, erbium-doped fiber, and receiver module into an integrated optical transceiver module. This optical transceiver module integration scheme utilizes a separate integration scheme: the pump source module and the receiver module for the intensity noise suppression optical path are integrated separately, with the erbium-doped fiber serving as the hub. The two integrated modules are connected in series, and then further integrated and packaged into a single unit. The overall structure of the designed intensity noise suppression ASE optical transceiver module is disc-shaped, making it compatible with the fiber optic gyroscope system it is intended for. The fiber pigtail of the designed integrated module requires metallization, with the location of the fiber metallization determined by the distance between the receiving module and the perforation in the sidewalls of the integrated module.

[0029] The optical transceiver integrated module with relative intensity noise suppression for a fiber optic gyroscope of the present invention specifically includes the following structural designs:

[0030] The optical transceiver integrated module includes three parts: a pump source module, an erbium-doped fiber, and a receiving module. Among them, the pump source module includes a 980nm laser (LD) pump source, a waveguide wavelength division multiplexer (WDM), and a first Faraday reflector; the receiving module includes a polarization-maintaining filter isolator, a 50:50 waveguide polarization-maintaining coupler, a second Faraday reflector that realizes 90° polarization rotation, a detector, and a pigtail; and the erbium-doped fiber is the connecting part between the pump source module and the receiving module. Because the ASE light source is based on the principle of amplifying the spontaneous emission of erbium-doped fiber, the erbium-doped fiber is difficult to integrate into the integrated chip of the module, so the ASE light source and photodetector of the fiber optic gyroscope are integrated into two integrated modules that can be connected with erbium-doped fiber jumpers, namely Figure 2 (b) Pump source module and receiving module shown.

[0031] The specific structural design analysis of the designed erbium-doped fiber ASE light source transceiver module with intensity noise suppression for the fiber optic gyroscope is as follows:

[0032] (1) Integration solution of pump source module:

[0033] The pump source module of the designed integrated solution includes the laser pump source 14, the waveguide wavelength division multiplexer 15 and the first Faraday reflector 16 in the traditional ASE light source solution. Figure 3 (a) The specific implementation method is as follows: a 980nm laser is used as the pump light source, and a waveguide-type 980 / 1550nm WDM 15 is employed, which includes three effective ports: Port 1 on the left side of WDM 15 is directly coupled to the 980nm pump source tube core and fixed with matching glue. Port 2 on the left side of WDM 15 is connected to a first Faraday rotator crystal 161. The end face of the first Faraday rotator crystal 161 opposite to the end face of the WDM 15 is coated with a 1550nm band total reflection filter film 162; a first tubular magnet 163 is matched with the first Faraday rotator crystal 161. The first Faraday rotator crystal 161 is located inside the first tubular magnet 163 and is within the uniform magnetic field provided by the magnet. The right side of WDM 15 is connected to a window that can be connected to an erbium-doped fiber jumper and is fixed to the first erbium-doped fiber terminal 41 with matching glue.

[0034] Specifically, the pump light is transmitted to the erbium-doped fiber 4 through WDM15. The erbium-doped fiber generates spontaneous radiation under the action of the pump light. The radiated light of the erbium-doped fiber is transmitted in both forward and reverse directions. Among them, the reverse radiated light is reversely transmitted through WDM15 and coupled to the first Faraday reflector 16. After reflection, it returns to the erbium-doped fiber again and is radiated and output through the first erbium-doped fiber terminal 41 of the erbium-doped fiber 4.

[0035] In particular, the Faraday rotator crystal can rotate along the tubular magnet, thereby utilizing the magneto-optical effect to rotate the polarization direction of the light beam. The effect of the Faraday rotator crystal on the polarization state of the light beam is determined by the Faraday magneto-optical effect. By selecting the material, structure, and magnetic induction intensity B of the rotator crystal, the polarization state of the light beam reflected by the Faraday reflector can be changed and maintained stable. Figure 4 As shown, when the magnetic field is not particularly strong, the rotation angle θ of the polarization plane caused by the Faraday rotation effect F It is proportional to the distance L that light travels along the medium, the Verdet constant V of the medium, and the magnetic induction intensity B of the magnetic field:

[0036] θ F =VBL

[0037] (2) Integration solution of receiving module:

[0038] The receiver module of the designed integrated solution includes a polarization-maintaining filter isolator 17, a 50:50 polarization-maintaining waveguide coupler 18 and a detector in the traditional intensity noise suppression fiber gyroscope solution, and adopts a 2% reflection filter film 192 and a second Faraday rotator crystal 191 with a 90° polarization rotation to realize the function of a 99:1 polarization-maintaining coupler in the traditional intensity noise suppression ASE light source. Figure 3 (b) As shown. The second erbium-doped fiber terminal 42 is directly coupled to the polarization-maintaining filter isolator 17 in an axial direction; the other end of the polarization-maintaining filter isolator 17 is connected to the input port 1 of the 50:50 polarization-maintaining waveguide coupler 18. The forward radiation from the erbium-doped fiber is coupled into the coupler 18 through the polarization-maintaining filter isolator 17, and is coupled into the pigtail through output port 1 and transmitted to the second Faraday reflector 19 through output port 2. The light coupled into output port 1 is output through the pigtail, which is the output light of the module; the light from output port 2 is rotated in polarization state and reflected by the second Faraday reflector 19, becoming backward-transmitted light with a polarization state rotated by 90°. Like the external return light input in the reverse direction through the pigtail, it is reversely transmitted through the coupler 18 and coupled to input port 2, and detected by the detector 20. Among them, the portion of the return light coupled to input port 1 is lost by the filter isolator 17 and will not continue to be transmitted to the erbium-doped fiber or even the pump source module.

[0039] Each optical element in the integrated module is controlled by the base accompanying plate (light source heat sink 271, accompanying plates 272-277 in the figure) to ensure the coaxiality of the optical path, and thereby fix each optical element to the ceramic substrate.

[0040] (3) Overall integration method and structural design of relative intensity noise suppression ASE light source transceiver module:

[0041] The pump source module 22 and the receiving module 23, as well as the erbium-doped optical fiber 4 between them, are placed in the same integrated unit. The erbium fiber is looped along the inner wall of the structure in the designed groove. The circuits of the pump source and its cooler, as well as the circuits of the detector, are implemented on a circular circuit board that matches the bottom of the module housing. The overall structure is as follows: Figure 5 shown.

[0042] From the perspective of structural design, the overall size of the relative intensity noise suppression ASE light source transceiver integrated module is limited by the sizes of the pump source module and the receiving module on the one hand; and by the bending radius that the erbium fiber can tolerate and the length of the erbium fiber on the other hand.

[0043] Because it is used in the fiber optic gyroscope system, in order to connect with the sensitive ring (fiber optic ring + Y-waveguide module) of the subsequent fiber optic gyroscope and facilitate the structural architecture and layout of the entire fiber optic gyroscope system, the present invention designs the relative intensity noise suppression ASE light source transceiver integrated module into a thin cylindrical shape, and the pigtail is led out from the hole in the side wall of the cylinder along the tangential direction, avoiding the bending distance required for fiber coiling when the pigtail is led out along the diameter direction, which helps to reduce the system structure size.

[0044] also, Figure 6 This is a partially enlarged schematic diagram of the polarization-maintaining fiber pigtail terminal 21. The polarization-maintaining optical fiber 25 is fixed in the silica U-shaped groove 24, and the end face is cut and polished to make the fiber pigtail end face meet the requirements. The polarization-maintaining fiber pigtail terminal 21 is then axially coupled to the waveguide coupler 18. In order to hermetically seal the entire module, a section of the optical fiber after the fiber pigtail terminal needs to be metallized, namely the metallized optical fiber segment 26. The metallized optical fiber segment 26 is welded to the cylindrical side wall hole to achieve hermetic packaging of the integrated module.

[0045] From the perspective of optical path design, the present invention describes an integrated solution for a high-precision fiber optic gyroscope intensity noise suppression ASE light source and a detector optical transceiver module. This solution can improve the integration of the high-precision fiber optic gyroscope optical transceiver module while reducing the optical path error, providing an effective and feasible solution for the integrated and miniaturized development of high-precision fiber optic gyroscopes.

Claims

1. An optical transceiver integrated module with relative intensity noise suppression for a fiber optic gyroscope, characterized in that: include: A pump source module, an erbium-doped optical fiber and a receiving module, wherein the pump source module and the receiving module are connected via the erbium-doped optical fiber; The pump source module includes a laser pump source, a waveguide wavelength division multiplexer, and a first Faraday reflector. The waveguide wavelength division multiplexer includes three ports, a left port 1 is axially coupled to the laser pump source tube core, a left port 2 is connected to the first Faraday reflector, and a right port is connected to the first erbium-doped fiber terminal of the erbium-doped fiber; The receiving module includes a polarization-maintaining filter isolator, a 50:50 polarization-maintaining waveguide coupler, a second Faraday reflector, a detector, and a pigtail. The second erbium-doped fiber terminal of the erbium-doped fiber is axially coupled to the polarization-maintaining filter isolator; the 50:50 polarization-maintaining waveguide coupler includes two input ports and two output ports, wherein the other end of the polarization-maintaining filter isolator is connected to input port 1, input port 2 is connected to the detector, output port 1 is connected to the pigtail, and output port 2 is connected to the second Faraday reflector; The first Faraday reflector includes a first Faraday rotator crystal, a total reflection filter film, and a first tubular magnet; the left side port 2 of the waveguide wavelength division multiplexer is connected to the first Faraday rotator crystal, and the end surface of the first Faraday rotator crystal opposite to the end surface of the left side port 2 is coated with a total reflection filter film; the first Faraday rotator crystal is located inside the first tubular magnet and can rotate along the first tubular magnet; The second Faraday reflector includes a second Faraday rotator crystal, a 2% reflection filter film, and a second tubular magnet; the second output port of the polarization-maintaining filter isolator is connected to the second Faraday rotator crystal, and the end surface of the second Faraday rotator crystal opposite to the end surface connected to the second output port is coated with a 2% reflection filter film; the second Faraday rotator crystal is located inside the second tubular magnet and can rotate along the second tubular magnet; The pump source module, erbium-doped fiber and receiving module are encapsulated in the same thin cylindrical structure. The erbium-doped fiber is looped in a groove on the inner wall of the thin cylindrical structure, and the pigtail is led out from the side wall hole of the thin cylindrical structure along the tangential direction. Each optical element in the integrated module is controlled by a substrate companion plate to ensure the coaxiality of the optical path, and thereby fix each optical element to the ceramic substrate.

2. The optical transceiver integrated module according to claim 1, wherein: In the pump source module, the pump light is transmitted to the erbium-doped fiber through a waveguide wavelength division multiplexer. The erbium-doped fiber generates spontaneous radiation under the action of the pump light. The radiated light of the erbium-doped fiber is transmitted in both forward and reverse directions. Among them, the reverse radiated light is reversely transmitted through the waveguide wavelength division multiplexer and coupled to the first Faraday reflector. After being reflected by the first Faraday reflector, it returns to the erbium-doped fiber again and is radiated and output through the second erbium-doped fiber terminal of the erbium-doped fiber.

3. The optical transceiver integrated module according to claim 2, wherein: In the receiving module, forward radiation from the erbium-doped optical fiber is coupled into a 50:50 polarization-maintaining waveguide coupler via a polarization-maintaining filter isolator, and is coupled into a pigtail via output port one and transmitted to a second Faraday reflector via output port two. The light coupled into output port one is output via the pigtail, i.e., the output light of the integrated module. The light from output port two is polarized and reflected by the second Faraday reflector, becoming backward-transmitted light with a polarization state rotated by 90°. This backward-transmitted light and external return light input in reverse via the pigtail are again reversely transmitted through the 50:50 polarization-maintaining waveguide coupler, coupled to input port two, and detected by a detector.

4. The optical transceiver integrated module according to claim 1, wherein: The pigtail includes a metallized fiber segment, which is welded to the sidewall hole of the thin cylindrical structural member; the position of the metallized fiber segment in the pigtail is determined by the distance between the receiving module and the sidewall hole of the thin cylindrical structural member.

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