An optical transceiver integrated assembly for a triaxial integrated fiber-optic gyroscope

Abstract

The application discloses a light receiving and transmitting integrated assembly for a three-axis integrated optical fiber gyroscope, comprising a light source module, a light splitting module, a polarization control module, an output tail fiber and a detector module, adopts a high-bi fiber gyroscope light source tube core as a light source, realizes separation of three-axis light paths and effective separation of output and return beams through cooperation of the light splitting module and the polarization control module, the output beam is output through the output tail fiber, and the return beam is received and detected by a photosensitive surface of the detector module. The light receiving and transmitting integrated assembly can improve integration of a three-axis optical fiber gyroscope light receiving and transmitting module and reduce influence of environmental factors on the light path, and provides an effective and feasible scheme for integration and miniaturization of the optical fiber gyroscope.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical path design, and particularly relates to an optical path structure integration scheme design of a three-axis integrated optical fiber gyroscope optical transceiver assembly. BACKGROUND

[0002] As an angular velocity sensor, the optical fiber gyroscope is widely used in the field of inertial navigation, can monitor the angular velocity and attitude of a carrier, and generally needs three optical fiber gyroscopes arranged in three orthogonal directions in an inertial navigation system to monitor the attitude change of the carrier in the whole three-dimensional space. In many application fields such as small unmanned aerial vehicles and microsatellites, in addition to the requirement of navigation accuracy, the sensing module also needs to be small in size, low in power consumption and high in reliability. The traditional light and small three-axis integrated optical fiber gyroscope mainly adopts the following modes: small-diameter optical fiber winding, device miniaturization, common light source and circuit board, but each optical element is still a separate unit. In addition, the number of tail fibers and fusion points is large, which reduces the reliability of the optical transceiver module.

[0003] The difficulty of the three-axis integrated optical transceiver assembly integration scheme lies in the possible mutual crosstalk between the three-axis optical paths, the electromagnetic interference between the light source and the detector, and the temperature control and heat dissipation of the active components in the module. Since these problems are difficult to handle, there is no mature commercial optical fiber gyroscope optical transceiver integration assembly in China at present. The reported optical fiber gyroscope optical transceiver integration assembly is a single-axis chip optical transceiver integration assembly. This scheme adopts a waveguide coupler, needs chip-level heterogeneous integration, has a large process difficulty, and is relatively difficult to implement. SUMMARY

[0004] The purpose of the present application is to realize the integration of the optical transceiver module in the three-axis optical fiber gyroscope, and an optical path integration scheme of the three-axis integrated optical transceiver module is proposed. The optical path structure adopts a design idea of spatial light transmission coupling, the process is compatible with the process in the communication field, and is beneficial to mass production of domestic products. Moreover, the scheme can realize the function of multi-axis common path, and has far-reaching significance for the miniaturization of optical fiber gyroscopes.

[0005] An optical transceiver integration assembly for a three-axis integrated optical fiber gyroscope, comprising a light source module, a light splitting module, a polarization control module, an output tail fiber and a detector module.

[0006] The light source module comprises an SLD light source die (1) and a light source collimating lens (2), and the light source collimating lens (2) is arranged at the rear end of the light emitting surface of the SLD light source die (1).

[0007] The light splitting module comprises a first NPBS (3), a second NPBS (4), an HR coating (5), a first PBS (6), a second PBS (7), and a third PBS (8). The first NPBS (3) and the second NPBS (4) have equal transmittance and reflectance for parallel polarized p light and vertical polarized s light. The first PBS (6), the second PBS (7), and the third PBS (8) are all transmissive to p light and all reflective to s light. The first NPBS (3) is arranged on the right side of the light source collimating lens (2), and the first PBS (6) is arranged on the right side of the first NPBS (3). The second NPBS (4) is arranged below the first NPBS (3), and the second PBS (7) is arranged on the right side of the second NPBS (4). The HR coating (5) is arranged below the second NPBS (4), and the third PBS (8) is arranged on the right side of the HR coating (5) and obliquely below the second PBS (7).

[0008] The polarization control module comprises a non-reciprocal Faraday optical rotator (11) and a half-wave plate (12). The polarization control module is arranged on the right side of the light splitting module. After the light beam output from the light splitting module passes through the polarization control module, the polarization direction is rotated by 90°. After the light beam returned from the output pigtail passes through the polarization control module, the polarization direction remains unchanged. Alternatively, after the light beam output from the light splitting module passes through the polarization control module, the polarization direction remains unchanged. After the light beam returned from the output pigtail passes through the polarization control module, the polarization direction is rotated by 90°.

[0009] The detector module comprises a first focusing lens (91), a second focusing lens (92), a third focusing lens (93), a first detector (101), a second detector (102), and a third detector (103). The first focusing lens (91) and the first detector (101) are arranged above the first PBS (6). The second focusing lens (92) and the second detector (102) are arranged below the second PBS (7). The third focusing lens (93) and the third detector (103) are arranged below the third PBS (8).

[0010] The output pigtail comprises a first pigtail collimating mirror (131), a second pigtail collimating mirror (132), a third pigtail collimating mirror (133), a first polarization maintaining pigtail (141), a second polarization maintaining pigtail (142), and a third polarization maintaining pigtail (143). The output pigtail is arranged on the right side of the polarization control module to realize the output of three-axis light beams.

[0011] Further, the ratio of the transmittance and reflectance of the first NPBS (3) is 1:2, and the ratio of the transmittance and reflectance of the second NPBS (4) is 1:1.

[0012] Further, the light beam of the light source module is p light, after being incident to the first NPBS (3), the transmitted light (p light) is incident to the first PBS (6), the first PBS (6) transmits all the p light and is incident to the polarization control module, the polarization direction of the light beam is rotated by 90° and becomes s light, and is emitted through the first tail fiber collimating mirror (131) and the first polarization maintaining tail fiber (141); meanwhile, the s light returned from the first polarization maintaining tail fiber (141) keeps the polarization direction unchanged after passing through the polarization control module, is reflected to the first focusing lens (91) through the first PBS (6), is received and detected by the photosensitive surface of the first detector (101) after being converged.

[0013] Further, the light beam of the light source module is p light, after being incident to the first NPBS (3), the reflected light (p light) is incident to the second NPBS (4), is incident to the second PBS (7) after being reflected, the second PBS (7) transmits all the p light and is incident to the polarization control module, the polarization direction of the light beam is rotated by 90° and becomes s light, and is emitted through the second tail fiber collimating mirror (132) and the second polarization maintaining tail fiber (142); meanwhile, the s light returned from the second polarization maintaining tail fiber (142) keeps the polarization direction unchanged after passing through the polarization control module, is reflected to the second focusing lens (92) through the second PBS (7), is received and detected by the photosensitive surface of the second detector (102) after being converged.

[0014] Further, the light beam of the light source module is p light, after being incident to the first NPBS (3), the reflected light (p light) is incident to the second NPBS (4), is incident to the HR coating (5) after being transmitted, the HR coating (5) reflects the light beam to the third PBS (8), the third PBS (8) transmits all the p light and is incident to the polarization control module, the polarization direction of the light beam is rotated by 90° and becomes s light, and is emitted through the third tail fiber collimating mirror (133) and the third polarization maintaining tail fiber (143); meanwhile, the s light returned from the third polarization maintaining tail fiber (143) keeps the polarization direction unchanged after passing through the polarization control module, is reflected to the third focusing lens (93) through the third PBS (8), is received and detected by the photosensitive surface of the third detector (103) after being converged.

[0015] The advantages and positive effects of the application are as follows:

[0016] The optical transceiver integrated assembly can effectively avoid mutual crosstalk between the light paths by adopting the polarization-independent beam splitting prism (NPBS), the polarization-dependent beam splitting prism (PBS) and the polarization rotation control unit.

[0017] (1) The application "a light receiving and transmitting integrated assembly for a three-axis integrated fiber-optic gyroscope" has a universal structure scheme: it is applicable to fiber-optic gyroscopes using SLD light sources, and can be popularized to single-axis and double-axis fiber-optic gyroscope light receiving and transmitting modules by changing the layout and use of the light splitting prism in the light splitting module, thereby providing a reliable technical approach for the integration and miniaturization of light receiving and transmitting modules of light small fiber-optic gyroscopes.

[0018] (2) The application "a light receiving and transmitting integrated assembly for a three-axis integrated fiber-optic gyroscope" can realize full polarization maintaining transmission of the optical path through the use of the polarization control unit, avoiding the difficulty of stable performance of the polarization maintaining coupler in the traditional full polarization maintaining scheme of the fiber-optic gyroscope.

[0019] (3) In the light path structure scheme of the application "a light receiving and transmitting integrated assembly for a three-axis integrated fiber-optic gyroscope", the theoretical utilization efficiency of optical power is more than 90%, avoiding the waste of 50% of the branch optical power in the 2x2 coupler in the traditional three-axis integrated fiber-optic gyroscope, significantly improving the power utilization efficiency and also being conducive to the improvement of the signal-to-noise ratio of the system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a fiber-optic gyroscope structure using traditional separate components, wherein "·" represents the optical fiber fusion point.

[0021] Figure 2 It is a fiber-optic gyroscope structure using the three-axis integrated light receiving and transmitting assembly designed in the application, wherein "·" represents the optical fiber fusion point.

[0022] Figure 3 It is the optical path structure diagram of the three-axis integrated light receiving and transmitting assembly in the application "a light receiving and transmitting assembly integrated scheme for a three-axis integrated fiber-optic gyroscope".

[0023] Figure 4 It is a schematic diagram of the principle of polarization state rotation control of the polarization control module of the designed three-axis integrated light receiving and transmitting assembly. represents the direction of light beam propagation; represents the polarization direction of the light beam.

[0024] In the figure: 1-SLD light source die, 2-light source collimating lens, 3-first NPBS (1:2), 4-second NPBS (1:1), 5-HR coating, 6-first PBS, 7-second PBS, 8-third PBS, 91 / 92 / 93-focusing lens, 101 / 102 / 103-detector, 11-non-reciprocal Faraday rotator, 12-half-wave plate, 131 / 132 / 133-tail fiber collimating mirror, 141 / 142 / 143-polarization maintaining tail fiber. DETAILED DESCRIPTION

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

[0026] This invention proposes an integrated solution for the optical transceiver module for the miniaturization and integration of a three-axis integrated fiber optic gyroscope, which meets high application requirements. Figure 1 The image shows the basic optical path structure of a traditional three-axis integrated fiber optic gyroscope. Figure 2 The figure shows the optical path structure of a fiber optic gyroscope using the integrated optical transceiver assembly designed according to this invention. As can be seen from the figure, traditional fiber optic gyroscope designs have many discrete components, resulting in a large overall size, numerous fiber pigtails, and many fusion splices. The triaxial integrated optical transceiver assembly designed by this invention effectively reduces the number of components and the overall size, while significantly reducing the number of pigtail fusion splices. This reduces nonlinear errors introduced by environmental factors affecting fiber characteristics and errors introduced by backscattering at fiber fusion splices. Figure 3 The invention specifically illustrates the structural scheme and optical path transmission route of the integrated optical transceiver assembly designed in this invention. The key to this invention lies in the design of the optical path scheme and the overall structural layout of the assembly. The integrated optical transceiver assembly scheme adopted in this invention is as follows: using a high-polarization fiber optic gyroscope light source chip, and through the cooperation of a beam splitting module and a polarization control module, the separation of the three-axis optical path and the effective separation of the output and return beams are achieved, and a simple and feasible full polarization-maintaining scheme for the fiber optic gyroscope optical path is realized. The specific implementation scheme is described below.

[0027] An integrated optical transceiver assembly for a three-axis fiber optic gyroscope includes a light source module, a beam splitter module, a polarization control module, an output pigtail, a detector module, and collimating and focusing lenses. The specific optical path structure and light transmission path are as follows: Figure 3 As shown:

[0028] (1) Light source module

[0029] The designed triaxial integrated optical transceiver module includes an SLD light source chip 1, a light source collimating lens 2, and a temperature control unit for the light source. The SLD light source chip emits a broadband Gaussian beam and is one of the core components of the module. The collimating lens then converges and collimates the divergent beam emitted from the light source chip into parallel light.

[0030] (2) Spectrometer

[0031] The beam splitter module of the designed triaxial integrated optical transceiver assembly consists of two NPBSs as power distribution execution units; three PBSs as units for separating the output beam and the return beam of the pigtail; and a high reflectivity (HR) coating to change the propagation direction of the beam.

[0032] In order to make the optical power of the three light beams close, the transmittance and reflectance of the two NPBSs are different, wherein T:R of NPBS3 is 1:2, and T:R of NPBS4 is 1:1 compared with NPBS3.

[0033] The transmittance and reflectance of the NPBS in the light splitting module are equal for p light and s light (Tp≈Ts, Rp≈Rs); the PBS is used to transmit all p light (Tp≈1, Rp≈0) and reflect all s light (Ts≈0, Rs≈1) of the module output, so as to separate the outgoing light beam and the return light beam.

[0034] (3) Polarization control module

[0035] The polarization control module of the designed three-axis integrated optical transceiver assembly is composed of a non-reciprocal Faraday rotator 11 and a half-wave plate 12. In order to distinguish the polarization state of the outgoing light beam of the designed three-axis integrated optical transceiver assembly from the polarization state of the return light beam of the fiber, the PBS in the light splitting module is used to make the transmittance and reflectance of the outgoing light beam and the return light beam of the module different. For example, the actual optical path structure adopted in the present application is used: the polarization control module mentioned above is non-reciprocal for the light in the output / return direction, and the polarization is changed, as shown in the figure, so that the output p light (parallel polarized light) is rotated by 90° in the polarization direction after passing through the polarization control module, and becomes s light (perpendicular polarized light), while the s light returned from the fiber does not change the polarization direction after passing through the polarization control module. Figure 4

[0036] (4) Detector module

[0037] The detector module of the designed three-axis integrated optical transceiver assembly mainly includes photodiode (PD) chips 101, 102 and 103 as system detectors, and focusing lenses 91, 92 and 93 placed in front of the photodiode chips, which are the final receiving units of the module and convert the received optical signals into electrical signals.

[0038] The light source of the optical transceiver integrated assembly proposed in the present application adopts a high-bi SLD light source die (which is adjusted to p light in the optical path of the present design), and the polarized light output by the light source die 1 is a divergent light beam. After collimation by the collimating lens 2, the light beam is incident on the polarization-independent light splitting prism (NPBS) 3. The light splitting ratio of the NPBS for s light and p light is the same, and the PBS is used to transmit all p light (Tp≈1, Rp≈0) and reflect all s light (Ts≈0, Rs≈1) of the module output, so as to separate the outgoing light beam and the return light beam. p p s s

[0039] ​​​​​The propagation process of light in the light splitting module does not involve the transformation of the polarization state, and the exiting light beam is always p light. The transmission light beams of PBS-6, PBS-7 and PBS-8 are changed in polarization state after passing through the non-reciprocal polarization control module 11+12, that is, the polarization state is transformed from p light to s light, that is, the transmission light of the polarization maintaining fiber 141, 142 and 143 is s light, and the light beam transmitted back by 141, 142 and 143 remains s light after passing through the polarization control module 11+12, and the specific principle and process are as shown in Figure 4

[0040] The return light beams transmitted back by the tail fibers 141, 142 and 143 remain s light after passing through the polarization control module 11+12, and are all reflected after passing through PBS-6, PBS-7 and PBS-8 respectively, that is, the separation of the output light path and the return light path can be realized, and the return light beams are converged by the focusing lenses 91-93 and received and detected by the light sensitive surfaces of the detectors 101-103. The optical signals received by the detectors are converted into electrical signals, and then processed by the subsequent signal processing and preamplification circuit and output by the pins of the assembly.

[0041] The application expounds an integrated scheme of a three-axis integrated optical fiber gyroscope light transceiver module from the perspective of light path scheme design, which can improve the integration of the three-axis optical fiber gyroscope light transceiver module while reducing the influence of environmental factors on the light path, and provides an effective and feasible scheme for the integration and miniaturization of the light fiber gyroscope.​

Claims

1. An integrated optical transceiver assembly for a three-axis integrated fiber optic gyroscope, characterized in that, Includes a light source module, a beam splitting module, a polarization control module, an output pigtail, and a detector module; The light source module includes an SLD light source chip (1) and a light source collimating lens (2). The light source collimating lens (2) is disposed at the rear end of the light-emitting surface of the SLD light source chip (1). The beam splitting module includes a first NPBS (3), a second NPBS (4), an HR coating (5), a first PBS (6), a second PBS (7), and a third PBS (8). The first NPBS (3) and the second NPBS (4) have equal transmittance and reflectance for parallel polarized p-light and vertically polarized s-light. The first PBS (6), the second PBS (7), and the third PBS (8) transmit all p-light and reflect all s-light. The first NPBS (3) is located to the right of the collimating lens (2) of the light source, and the first PBS (6) is located to the right of the first NPBS (3). The second NPBS (4) is located below the first NPBS (3), and the second PBS (7) is located to the right of the second NPBS (4). The HR coating (5) is located below the second NPBS (4), and the third PBS (8) is located to the right of the HR coating (5) and diagonally below the second PBS (7). The polarization control module includes a non-reciprocal Faraday rotator (11) and a half-wave plate (12). The polarization control module is located on the right side of the beam splitter. The beam output from the beam splitter is rotated 90° after passing through the polarization control module, and the beam returning from the output pigtail is kept unchanged after passing through the polarization control module. Alternatively, the beam output from the beam splitter is kept unchanged after passing through the polarization control module, and the beam returning from the output pigtail is rotated 90° after passing through the polarization control module. The detector module includes a first focusing lens (91), a second focusing lens (92), a third focusing lens (93), a first detector (101), a second detector (102), and a third detector (103). The first focusing lens (91) and the first detector (101) are located above the first PBS (6), the second focusing lens (92) and the second detector (102) are located below the second PBS (7), and the third focusing lens (93) and the third detector (103) are located below the third PBS (8). The output pigtail includes a first pigtail collimating lens (131), a second pigtail collimating lens (132), a third pigtail collimating lens (133), a first polarization-maintaining pigtail (141), a second polarization-maintaining pigtail (142), and a third polarization-maintaining pigtail (143). The output pigtail is located to the right of the polarization control module to realize the output of a three-axis beam.

2. The optical transceiver integrated assembly for a three-axis integrated fiber optic gyroscope according to claim 1, characterized in that, The ratio of transmittance to reflectance of the first NPBS (3) is 1:2, and the ratio of transmittance to reflectance of the second NPBS (4) is 1:

1.

3. The optical transceiver integrated assembly for a three-axis integrated fiber optic gyroscope according to claim 1 or 2, characterized in that, The emitted beam of the light source module is p-beam. After being incident on the first NPBS (3), the transmitted light is incident on the first PBS (6). The first PBS (6) transmits all the p-beam and is incident on the polarization control module. The polarization direction of the beam is rotated by 90° and becomes s-beam. It is emitted through the first pigtail collimating lens (131) and the first polarization-maintaining pigtail (141). At the same time, the s-beam returning from the first polarization-maintaining pigtail (141) remains unchanged after passing through the polarization control module. It is reflected by the first PBS (6) to the first focusing lens (91), and after converging, it is received and detected by the photosensitive surface of the first detector (101).

4. The optical transceiver integrated assembly for a three-axis integrated fiber optic gyroscope according to claim 3, characterized in that, The emitted beam of the light source module is p-beam. After being incident on the first NPBS (3), the reflected light is incident on the second NPBS (4), and after reflection, it is incident on the second PBS (7). The second PBS (7) transmits all the p-beam and is incident on the polarization control module. The polarization direction of the beam is rotated by 90° and becomes s-beam. It is emitted through the second pigtail collimating lens (132) and the second polarization-maintaining pigtail (142). At the same time, the s-beam returning from the second polarization-maintaining pigtail (142) has its polarization direction unchanged after passing through the polarization control module. It is reflected by the second PBS (7) to the second focusing lens (92), and after converging, it is received and detected by the photosensitive surface of the second detector (102).

5. The optical transceiver integrated assembly for a three-axis integrated fiber optic gyroscope according to claim 4, characterized in that, The emitted beam of the light source module is p-beam. After being incident on the first NPBS (3), the reflected light is incident on the second NPBS (4), and after transmission, it is incident on the HR coating (5). The HR coating (5) reflects the beam to the third PBS (8). The third PBS (8) transmits all the p-beam and it is incident on the polarization control module. The polarization direction of the beam is rotated by 90° and becomes s-beam. It is emitted through the third pigtail collimating lens (133) and the third polarization-maintaining pigtail (143). At the same time, the s-beam returning from the third polarization-maintaining pigtail (143) has its polarization direction unchanged after passing through the polarization control module. It is reflected by the third PBS (8) to the third focusing lens (93), and after converging, it is received and detected by the photosensitive surface of the third detector (103).

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