A photoelectric detector with adjustable coupling efficiency for fiber optic gyroscope

Abstract

The present invention belongs to the technical field of fiber optic gyroscope and fiber optic sensor, and specifically discloses a photoelectric detector with adjustable coupling efficiency for fiber optic gyroscope, including a tube shell, a first carrier, a piezoelectric micromirror, a fiber optic collimator, a nozzle, a first reflector, a second reflector, a second carrier, a PIN chip, and a circuit board ceramic substrate. The present invention monitors the peak height of the comb wave of the interference signal through the circuit system of the fiber optic gyroscope, and controls the coupling efficiency of the detector in real time through the light intensity closed-loop feedback system to ensure that the peak height of the comb wave remains consistent, thereby solving the problems of full-temperature zero bias fluctuation, short-term output data abnormality at low temperature cold start, and gradually increasing total optical path loss of the fiber optic gyroscope, and does not cause the scale factor drift problem caused by the change of the light source driving current.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber gyroscope and optical fiber sensing, and in particular relates to a photoelectric detector with adjustable coupling efficiency for an optical fiber gyroscope. Background Art

[0002] In the actual engineering application of fiber optic gyroscope, the detector is the end point of the fiber optic gyroscope optical path, which is responsible for converting the interference light intensity signal into an electrical signal. At present, the traditional photoelectric detector used in the fiber optic gyroscope adopts an 8-degree inclined fiber optic component and a photoelectric conversion chip to align and couple. The fiber optic component is fixed to the shell by soldering. The interior is all solid and has no moving parts. The detector coupling efficiency is a fixed value. In terms of environmental adaptability, especially wide temperature range environmental adaptability, fixed coupling efficiency detectors have many disadvantages, as follows:

[0003] First, the fiber optic gyroscope has the problem of zero bias fluctuation at all temperatures (-55~+85℃). The total optical path loss of the fiber optic gyroscope fluctuates within the full temperature range, resulting in fluctuations in the optical power reaching the detector and changes in the height of the interference light comb wave signal, causing the zero bias fluctuation of the fiber optic gyroscope. For the 1310nm band fiber optic gyroscope with a temperature-controlled light source chip, the typical value of the optical power change rate reaching the detector is ±10%, and the maximum fluctuation reaches ±20%. The power fluctuation is mainly contributed by the change in the output power of the light source and the change in the insertion loss of the Y waveguide. For the 850nm band low-power fiber optic gyroscope with no temperature control of the light source chip, the typical value of the optical power fluctuation reaching the detector is ±40%, and the maximum value is as high as ±60%. The power fluctuation comes from the drastic change in the luminous efficiency of the light source chip with temperature. Although the zero bias drift can be compensated by a temperature sensor combined with a temperature model, the optical path loss does not have strict repeatability with temperature changes, so the compensation can only have limited effect.

[0004] Second, the fiber optic gyroscope has an abnormal output data problem during a short period of cold start at -55°C. The luminous power of the 1310nm band light source chip is about 4-5 times that of normal temperature at -55°C. When cold started at -55°C, the power reaching the detector exceeds the saturation light intensity of the detector photoelectric conversion chip (PIN chip), and the fiber optic gyroscope digital closed-loop control system works abnormally, resulting in abnormal output data of the fiber optic gyroscope. 5-10 seconds after power-on, the thermoelectric cooler heats the light source chip to nearly 25°C before the gyroscope can output the correct angular velocity information. Therefore, the fiber optic gyroscope data is unavailable in the first 5-10 seconds after startup.

[0005] Third, after long-term use, the total optical path loss of the fiber optic gyroscope will gradually increase. The luminous efficiency of the light source chip will decrease, the coupling point of the light source and the Y-waveguide will be slightly displaced, and the alignment accuracy will decrease, especially for non-hermetic Y-waveguides, where the coupling point is greatly affected by external pollutants such as water vapor. The above series of factors will cause the power reaching the detector to gradually decrease after long-term use of the fiber optic gyroscope, and the signal-to-noise ratio of the interference signal will decrease, resulting in the degradation of the zero-bias stability of the fiber optic gyroscope after long-term use.

[0006] The above three problems are all similar to the problem of optical power fluctuation. In engineering, the problem of optical power fluctuation can be solved by adjusting the optical power in real time by changing the light source driving current, but this solution will cause the scale factor to drift, and medium and high precision fiber optic gyroscopes cannot be used. It can only be applied to low-precision gyroscopes that have very low requirements for scale factor stability. Summary of the invention

[0007] The purpose of the present invention is to solve the problems of full-temperature zero bias fluctuation, short-time output data abnormality at low-temperature cold start and gradual increase in total optical path loss in a fiber optic gyroscope, and a photoelectric detector with adjustable coupling efficiency for a fiber optic gyroscope is proposed.

[0008] The technical solution of the present invention is: a photoelectric detector with adjustable coupling efficiency for a fiber optic gyroscope, comprising a tube shell, a piezoelectric micromirror, a fiber optic collimator, a first reflector, a second reflector, a PIN chip, a nozzle, a second carrier and a circuit board ceramic substrate;

[0009] The piezoelectric micromirror, the optical fiber collimator, the first reflector, the second reflector and the PIN chip are all located inside the tube shell; the piezoelectric micromirror is provided with a bias voltage whose size and positive and negative values ​​are adjustable; the nozzle is located on the outer wall of the tube shell, and the optical fiber collimator is located inside the nozzle; the circuit board ceramic substrate is located inside the tube shell; the center of the first reflector is located on the central axis of the nozzle; the PIN chip is located on the second carrier; the line connecting the center point of the first reflector and the center point of the second reflector is parallel to the short side of the tube shell, and the line connecting the center point of the PIN chip and the center point of the second reflector is parallel to the long side of the tube shell.

[0010] The beneficial effects of the present invention are:

[0011] The present invention adds a piezoelectric micromirror, a first reflector, a second reflector and a fiber collimator inside a photodetector tube shell, and sets a bias voltage with adjustable size and positive and negative values ​​on the piezoelectric micromirror to control the coupling efficiency of the photodetector in real time, thereby effectively solving the three problems of full-temperature zero bias fluctuation, short-term output data abnormality during low-temperature cold start, and gradually increasing total optical path loss of the fiber optic gyroscope, without causing the problem of scale factor drift caused by changes in the light source driving current.

[0012] Preferably, the photodetector further comprises a first carrier; the first carrier is located at one end of the circuit board ceramic substrate close to the nozzle; the piezoelectric micromirror is located on the first carrier, and the first reflector is located on the piezoelectric micromirror; the first carrier, the second reflector and the second carrier are arranged in an "L" shape in space;

[0013] The optical fiber collimator is used to transmit the optical signal to the first reflector;

[0014] The first reflector is used to receive the optical signal, rotate according to the bias voltage and adjust the transmission direction of the optical signal and the ratio of the light spot energy received by the PIN chip to the total light spot energy, and output the adjusted optical signal to the second reflector;

[0015] The second reflector is used to receive the adjusted optical signal and reflect the adjusted optical signal to the PIN chip;

[0016] The PIN chip is used to receive the optical signal of the second reflector, perform photoelectric conversion on the optical signal of the second reflector, and output a weak current signal to achieve coupling efficiency regulation.

[0017] Preferably, the photoelectric detector further comprises a first carrier; the piezoelectric micromirror is located on the first carrier, the second reflector is located on the piezoelectric micromirror, and the first reflector, the first carrier and the second carrier are arranged in an "L" shape in space;

[0018] The optical fiber collimator is used to transmit the optical signal to the first reflector;

[0019] The first reflector is used to receive the optical signal and reflect the optical signal to the second reflector;

[0020] The second reflector is used to receive the optical signal of the first reflector, rotate according to the bias voltage, adjust the direction of optical signal transmission of the first reflector and the ratio of the light spot energy received by the PIN chip to the total light spot energy, and output the adjusted optical signal to the PIN chip;

[0021] The PIN chip is used to receive the optical signal of the second reflector, perform photoelectric conversion on the optical signal of the second reflector, and output a weak current signal to achieve coupling efficiency regulation.

[0022] Preferably, the chip side length of the piezoelectric micromirror is 0.8mm-1.5mm; the diameter of the first reflector is Ф0.5mm-Ф1.2mm, the rotation angle range of the first reflector is ±2.4°, the driving voltage of the first reflector is ≤5V, and the rotation speed of the first reflector is ≤5ms.

[0023] Preferably, an amplifier circuit is further provided on the ceramic substrate of the circuit board for receiving the weak current signal output by the PIN chip, performing current-to-voltage conversion and three-stage amplification on the weak current signal, and outputting the amplified voltage signal.

[0024] Preferably, the tube shell is provided with 8 signal pins, namely: a first pin, a second pin, a third pin, a fourth pin, a fifth pin, a sixth pin, a seventh pin and an eighth pin; the first pin, the second pin, the third pin and the fourth pin are located on a long side of the tube shell close to the second carrier; the fifth pin, the sixth pin, the seventh pin and the eighth pin are located on the other long side of the tube shell;

[0025] Among them, the first pin is the Vss interface, the second pin is the first ground terminal, the third pin is suspended, the fourth pin is the output interface, the fifth pin is the second ground terminal, the sixth pin is the piezoelectric micromirror Vcc1 interface, the seventh pin is the Vcc interface, and the eighth pin is the piezoelectric micromirror Vss1 interface; the amplification circuit is connected to the signal pin by gold wire bonding.

[0026] Preferably, the optical fiber collimator adopts C-lens as the collimating lens and is sealed with a metal tube.

[0027] Preferably, the distance between the PIN chip and the second reflector is 5 mm-15 mm.

[0028] The beneficial effects of the above preferred solution are:

[0029] The above preferred solution can effectively adjust the coupling efficiency of the photodetector by applying a bias voltage to the piezoelectric micromirror, changing the angle of the first reflector or the second reflector built into the piezoelectric micromirror, and then changing the proportion of input light received by the photosensitive surface of the PIN chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the photoelectric detector with adjustable coupling efficiency for the fiber optic gyroscope provided in the first embodiment of the present invention.

[0031] Figure 2 The figure shows a schematic diagram of the optical path system of the fiber optic gyroscope provided in Example 3 of the present invention.

[0032] Figure 3 Shown is a schematic diagram of the optical path provided in Example 3 of the present invention.

[0033] Figure 4 The figure is a schematic diagram of the working principle of controlling the reflection direction of the piezoelectric micromirror to adjust the coupling efficiency when the bias voltage of the piezoelectric micromirror provided in Example 3 of the present invention is 0.

[0034] Figure 5The figure is a schematic diagram of the working principle of controlling the reflection direction of the piezoelectric micromirror to adjust the coupling efficiency when the bias voltage of the piezoelectric micromirror provided in Example 3 of the present invention is greater than 0.

[0035] Figure 6 The figure is a schematic diagram of the working principle of controlling the reflection direction of the piezoelectric micromirror to adjust the coupling efficiency when the bias voltage of the piezoelectric micromirror provided in Example 3 of the present invention is less than 0.

[0036] Figure numerals: 1. tube shell; 2. first carrier; 3. piezoelectric micromirror; 4. nozzle; 5. fiber collimator; 6. first reflector; 7. second reflector; 8. second carrier; 9. PIN chip; 10. circuit board ceramic substrate; 11. amplifier circuit; 12. first pin; 13. second pin; 14. third pin; 15. fourth pin; 16. fifth pin; 17. sixth pin; 18. seventh pin; 19. eighth pin. DETAILED DESCRIPTION

[0037] Now, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the accompanying drawings are only exemplary and are intended to explain the principles and spirit of the present invention, rather than to limit the scope of the present invention.

[0038] Embodiment 1:

[0039] like Figure 1 As shown, a photoelectric detector with adjustable coupling efficiency for a fiber optic gyroscope includes a tube shell 1, a piezoelectric micromirror 3, a fiber collimator 5, a first reflector 6, a second reflector 7, a PIN chip 9, a nozzle 4, a second carrier 8 and a circuit board ceramic substrate 10;

[0040] The piezoelectric micromirror 3, the optical fiber collimator 5, the first reflector 6, the second reflector 7 and the PIN chip 9 are all located inside the tube shell 1; the piezoelectric micromirror 3 is provided with a bias voltage whose size and positive and negative can be adjusted; the nozzle 4 is located on the outer wall of the tube shell 1, and the optical fiber collimator 5 is located inside the nozzle 4; the circuit board ceramic substrate 10 is located inside the tube shell 1; the center of the first reflector 6 is located on the central axis of the nozzle 4; the second carrier 8 is located on the edge of the circuit board ceramic substrate 10 which is perpendicular to the edge where the first reflector 6 is located, and the PIN chip 9 is located on the second carrier 8; the line connecting the center point of the first reflector 6 and the center point of the second reflector 7 is parallel to the short side of the tube shell 1, and the line connecting the center point of the PIN chip 9 and the center point of the second reflector 7 is parallel to the long side of the tube shell 1.

[0041] In this embodiment, the photodetector further comprises a first carrier 2; the first carrier 2 is located at one end of the circuit board ceramic substrate 10 close to the nozzle 4; the piezoelectric micromirror 3 is located on the first carrier 2, and the first reflector 6 is located on the piezoelectric micromirror 3; the first carrier 2, the second reflector 7 and the second carrier 8 are arranged in an "L" shape in space;

[0042] The optical fiber collimator 5 is used to transmit the optical signal to the first reflector 6;

[0043] The first reflector 6 is used to receive the optical signal, rotate according to the bias voltage and adjust the transmission direction of the optical signal and the ratio of the light spot energy received by the PIN chip 9 to the total light spot energy, and output the adjusted optical signal to the second reflector 7;

[0044] The second reflector 7 is used to receive the adjusted optical signal and reflect the adjusted optical signal to the PIN chip 9;

[0045] The PIN chip 9 is used to receive the optical signal of the second reflector 7, perform photoelectric conversion on the optical signal of the second reflector 7, and output a weak current signal to achieve coupling efficiency regulation.

[0046] The first carrier 2 faces the nozzle 4, and the first reflector 6 and the optical fiber collimator 5 of the input optical signal are at a 45° angle. The first carrier 2 needs to reserve the positive electrode, negative electrode and grounding gold wire bonding pad positions for the chip of the piezoelectric micromirror 3.

[0047] In this embodiment, the chip side length of the piezoelectric micromirror 3 is 0.8mm-1.5mm; the diameter of the first reflector 6 is Ф0.5mm-Ф1.2mm, the rotation angle range of the first reflector 6 is ±2.4°, the driving voltage of the first reflector 6 is ≤5V, and the rotation speed of the first reflector 6 is ≤5ms.

[0048] In this embodiment, an amplifier circuit 11 composed of electronic components such as capacitors, resistors, transistors and field effect transistors is prefabricated on the circuit board ceramic substrate 10, which is used to receive the weak current signal output by the PIN chip 9, and perform current-voltage conversion and three-stage amplification on the weak current signal to output the amplified voltage signal.

[0049] In this embodiment, the tube shell 1 is provided with 8 signal pins, namely: a first pin 12, a second pin 13, a third pin 14, a fourth pin 15, a fifth pin 16, a sixth pin 17, a seventh pin 18 and an eighth pin 19; the first pin 12, the second pin 13, the third pin 14 and the fourth pin 15 are located on one long side of the tube shell 1 close to the second carrier 8; the fifth pin 16, the sixth pin 17, the seventh pin 18 and the eighth pin 19 are located on the other long side of the tube shell 1;

[0050] Among them, the first pin 12 is a Vss (-5V) interface, the second pin 13 is a first ground terminal (GND), the third pin 14 is suspended, the fourth pin 15 is an output (Vout) interface, the fifth pin 16 is a second ground terminal (GND), the sixth pin 17 is a piezoelectric micromirror Vcc1 (5V) interface, the seventh pin 18 is a Vcc (5V) interface, and the eighth pin 19 is a piezoelectric micromirror Vss1 (-5V) interface; the amplifier circuit 11 connects the ground, input voltage and output signal of the amplifier circuit 11 to the signal pin on the tube shell 1 by gold wire bonding.

[0051] In this embodiment, the piezoelectric micromirror 3 is pasted on the first carrier 2, the first carrier 2 faces the nozzle 4, the center of the first reflector 6 is on the central axis of the nozzle 4, and the first reflector 6 in the piezoelectric micromirror 3 and the optical fiber collimator 5 of the input optical signal are at a 45° angle.

[0052] In this embodiment, the optical fiber collimator 5 uses a spherical lens (C-lens) as a collimating lens and is sealed with a metal tube; after coupling, the optical fiber collimator 5 is fixed inside the nozzle 4 by welding.

[0053] In this embodiment, the distance between the PIN chip 9 and the second reflector 7 is 5 mm-15 mm.

[0054] In this embodiment, taking the input optical fiber as the YOFC 1310nm small mode field single mode optical fiber (model: CS1011B) as an example, the specific parameters are selected as follows:

[0055] The collimating lens has a curvature radius of R = 0.8 mm, an outer diameter of Φ = 0.5 mm, and a length of L = 1.8 mm; the outer diameter of the optical fiber collimator 5 made of the collimating lens is Φ1.3 mm, the working distance of the optical fiber collimator 5 is 9 mm, and the beam waist radius is 22 um;

[0056] The chip size of the piezoelectric micromirror 3 is 1.0 mm*1.0 mm, the diameter of the first reflector 6 is Φ0.6 mm, the rotation angle is -1.0 deg~1.0 deg, the driving voltage is ≤5 V, and the rotation speed is <5 ms.

[0057] In this embodiment, the piezoelectric micromirror 3 is provided with a bias voltage with adjustable size and positive and negative; by adjusting the positive and negative and size of the bias voltage, the first reflector 6 is rotated, thereby adjusting the direction of light signal transmission and the proportion of the light spot energy received by the PIN chip 9 to the total energy of the light spot, so as to achieve coupling efficiency regulation. When no bias voltage is applied to the piezoelectric micromirror 3, half of the light spot is inside the photosensitive surface of the PIN chip 9, and half is outside the photosensitive surface of the PIN chip 9. When a forward bias voltage is applied to the piezoelectric micromirror 3, the first reflector 6 on the piezoelectric micromirror 3 rotates forward, the light spot moves toward the center of the photosensitive surface, the light spot on the photosensitive surface of the PIN chip 9 gradually increases, and the coupling efficiency of the detector increases. As the applied bias voltage continues to increase, the light spot continues to move after passing the center of the photosensitive surface, and the light spot will move out from the other side of the photosensitive surface, or even away from the photosensitive surface. Therefore, the size of the forward bias voltage needs to be controlled within a certain range according to actual conditions, and cannot be increased indefinitely. When a reverse bias voltage is applied to the piezoelectric micromirror 3, the first reflector 6 on the piezoelectric micromirror 3 rotates in the opposite direction, and the light spot on the photosensitive surface of the PIN chip 9 moves away from the center of the photosensitive surface. The light spot on the photosensitive surface of the PIN chip 9 gradually decreases, and the coupling efficiency of the photodetector decreases. As the reverse bias voltage increases, the light spot moves away from the photosensitive surface.

[0058] The present invention adjusts the bias voltage of the piezoelectric micromirror 3 by real-time monitoring the peak height voltage value of the comb wave output by the detector, and realizes the constant peak height of the comb wave output by the detector through the closed-loop feedback control system in the gyroscope. The scheme of the present invention can replace the traditional detector in the fiber optic gyroscope in situ without adding any optical devices. The size and optical fiber interface are exactly the same as those of the traditional detector. The two idle pins of the original ceramic 8-pin dual in-line package detector are used to adjust the DC voltage bias pins of the coupling efficiency.

[0059] Embodiment 2:

[0060] This embodiment also provides a method for implementing a photoelectric detector with adjustable coupling efficiency for a fiber optic gyroscope.

[0061] In this embodiment, the photodetector further comprises a first carrier 2; the piezoelectric micromirror 3 is located on the first carrier 2, the second reflector 7 is located on the piezoelectric micromirror 3, and the first reflector 6, the first carrier 2 and the second carrier 8 are arranged in an "L" shape in space;

[0062] The optical fiber collimator 5 is used to transmit the optical signal to the first reflector 6;

[0063] The first reflector 6 is used to receive the optical signal and reflect the optical signal to the second reflector 7;

[0064] The second reflector 7 is used to receive the optical signal of the first reflector 6, rotate according to the bias voltage, adjust the direction of the optical signal transmission of the first reflector 6 and the ratio of the light spot energy received by the PIN chip 9 to the total light spot energy, and output the adjusted optical signal to the PIN chip 9;

[0065] The PIN chip 9 is used to receive the optical signal of the second reflector 7, perform photoelectric conversion on the optical signal of the second reflector 7, and output a weak current signal to achieve coupling efficiency regulation.

[0066] Embodiment 3:

[0067] Based on Example 1, this example describes the specific working principle and process of the photoelectric detector with adjustable coupling efficiency for the fiber optic gyroscope proposed by the present invention.

[0068] In this embodiment, the optical path system of the fiber optic gyroscope is composed of a superluminescent diode light source, a 2*2 fiber coupler, a PIN-FET photodetector, a Y-waveguide integrated optical phase modulator and a polarization-maintaining fiber ring. The entire optical path is as follows: Figure 2 As shown in Figure 2, the PIN-FET photodetector is the end point of the optical path of the fiber optic gyroscope and is responsible for converting the interference light intensity signal into an electrical signal.

[0069] In this embodiment, if Figure 3 As shown, the optical signal is transmitted from the optical fiber collimator 5 to the first reflector 6 at the center of the piezoelectric micromirror 3. The first reflector 6 at the center of the piezoelectric micromirror 3 reflects the input optical signal by 90 degrees, so that the optical signal is transmitted to the second reflector 7. The second reflector 7 then reflects the optical signal by -90 degrees, so that the optical signal is finally transmitted to the photosensitive surface of the PIN chip 9. The PIN chip 9 converts the optical signal into a current signal, and the amplifier circuit 11 performs current-to-voltage conversion and amplification on the current signal. The photodetector pin outputs a voltage signal that is proportional to the light intensity.

[0070] When a bias voltage is applied to the piezoelectric micromirror 3, the first reflector 6 rotates under the force generated by the bias voltage, causing the optical signal input from the optical fiber collimator 5 to the first reflector 6 to rotate a certain angle compared with the original transmission path after being reflected by the first reflector 6. The optical signal is then reflected by the second reflector 7, and after being transmitted for a certain distance, the position of the light spot finally input to the PIN chip 9 is deflected. By adjusting the positive and negative and the magnitude of the bias voltage applied to the piezoelectric micromirror 3, the transmission direction of the light beam and the position of the light spot can be adjusted in real time, and the proportion of the light spot energy received by the PIN chip 9 to the total light spot energy can be controlled, so as to achieve real-time regulation of the coupling efficiency.

[0071] For the conventional detector, 100% of the light energy emitted by the 8-degree inclined optical fiber assembly is received by the PIN chip 9. Figure 4 As shown in FIG. 1 , when the bias voltage applied to the piezoelectric micromirror 3 is 0, the light energy received by the PIN chip 9 accounts for 50% of the total area of ​​the light spot, and the coupling efficiency is 50% at this time; Figure 5 As shown in FIG. 1 , when a positive bias voltage is applied to the piezoelectric micromirror 3, the light beam is deflected downward, the light energy received by the PIN chip 9 increases, and the coupling efficiency increases; Figure 6 As shown, when a negative bias voltage is applied to the piezoelectric micromirror 3, the light beam is deflected upward, the light energy received by the PIN chip 9 is reduced, and the coupling efficiency is reduced.

[0072] In this embodiment, the present invention solves the problem of power fluctuation of the fiber optic gyroscope at full temperature by real-time monitoring the voltage value of the peak height of the comb wave output by the detector. When the peak height decreases, the bias voltage value applied to the piezoelectric micromirror 3 is increased to increase the coupling efficiency of the detector; when the peak height decreases, the opposite is true. The present invention can ensure that the detector output peak is stable at a fixed value in a full temperature environment of -55~+85℃, so that the total optical path loss of the fiber optic gyroscope remains constant, thereby improving the full temperature accuracy of the fiber optic gyroscope. The present invention is particularly critical to improving the full temperature accuracy of the low-power 850nm band fiber optic gyroscope without a thermoelectric cooler.

[0073] In this embodiment, the problem of abnormal output during the cold start of the fiber optic gyroscope in the 1310nm band is addressed. This problem is mainly aimed at the special environment of the cold start of the fiber optic gyroscope in a high-altitude low-temperature environment. When cold-starting at a low temperature (such as -55°C), the output power of the light source is 4-5 times that of normal temperature. At this time, the photodetector optical chip is in a saturated state, outputting a DC signal and unable to output a normal comb wave. At the moment after starting, the present invention measures the resistance of the built-in thermistor of the light source, calculates the required photodetector responsivity through the known "light source chip temperature (or thermistor resistance)-output power" curve model, and outputs the corresponding negative voltage to the piezoelectric micromirror 3, reducing the coupling efficiency of the photodetector, so that the photodetector can instantly output a normal comb wave without waiting for the light source temperature control to slowly heat the chip temperature from -55°C to 25°C. Since the response time of the piezoelectric micromirror 3 is less than 5ms, the cold start preparation time of the fiber optic gyroscope can be free from the temperature control rate of the light source.

[0074] In this embodiment, the problem of gradually increasing optical path loss after long-term use of the fiber optic gyroscope is solved by real-time monitoring of the voltage value of the comb wave peak height output by the detector. When the peak height decreases, the bias voltage value applied to the piezoelectric micromirror 3 is increased to increase the coupling efficiency of the detector; when the peak height decreases, the opposite is true.

[0075] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A photoelectric detector with adjustable coupling efficiency for a fiber optic gyroscope, characterized in that: It comprises a tube shell (1), a piezoelectric micromirror (3), a nozzle (4), an optical fiber collimator (5), a first reflector (6), a second reflector (7), a second carrier (8), a PIN chip (9) and a circuit board ceramic substrate (10); The piezoelectric micromirror (3), the optical fiber collimator (5), the first reflector (6), the second reflector (7) and the PIN chip (9) are all located inside the tube shell (1); the piezoelectric micromirror (3) is provided with a bias voltage whose size and positive and negative values ​​are adjustable; the nozzle (4) is located on the outer wall of the tube shell (1), and the optical fiber collimator (5) is located inside the nozzle (4); the circuit board ceramic substrate (10) is located inside the tube shell (1); the center of the first reflector (6) is located on the central axis of the nozzle (4); the PIN chip (9) is located on the second carrier (8); the line connecting the center point of the first reflector (6) and the center point of the second reflector (7) is parallel to the short side of the tube shell (1), and the line connecting the center point of the PIN chip (9) and the center point of the second reflector (7) is parallel to the long side of the tube shell (1).

2. The photoelectric detector with adjustable coupling efficiency according to claim 1, characterized in that: The photoelectric detector further comprises a first carrier (2); the first carrier (2) is located at one end of the circuit board ceramic substrate (10) close to the nozzle (4); the piezoelectric micromirror (3) is located on the first carrier (2), and the first reflector (6) is located on the piezoelectric micromirror (3); the first carrier (2), the second reflector (7) and the second carrier (8) are arranged in an "L" shape in space; The optical fiber collimator (5) is used to transmit the optical signal to the first reflector (6); The first reflector (6) is used to receive the optical signal, rotate according to the bias voltage, adjust the transmission direction of the optical signal and the ratio of the light spot energy received by the PIN chip (9) to the total light spot energy, and output the adjusted optical signal to the second reflector (7); The second reflector (7) is used to receive the adjusted optical signal and reflect the adjusted optical signal to the PIN chip (9); The PIN chip (9) is used to receive the optical signal of the second reflector (7), and to perform photoelectric conversion on the optical signal of the second reflector (7), and to output a weak current signal, thereby achieving coupling efficiency regulation.

3. The photoelectric detector with adjustable coupling efficiency according to claim 1, characterized in that: The photoelectric detector further comprises a first carrier (2); the piezoelectric micromirror (3) is located on the first carrier (2); the second reflector (7) is located on the piezoelectric micromirror (3); the first reflector (6), the first carrier (2) and the second carrier (8) are arranged in an "L" shape in space; The optical fiber collimator (5) is used to transmit the optical signal to the first reflector (6); The first reflector (6) is used to receive the optical signal and reflect the optical signal to the second reflector (7); The second reflector (7) is used to receive the optical signal of the first reflector (6), rotate according to the bias voltage, adjust the direction of optical signal transmission of the first reflector (6) and the ratio of the light spot energy received by the PIN chip (9) to the total light spot energy, and output the adjusted optical signal to the PIN chip (9); The PIN chip (9) is used to receive the optical signal of the second reflector (7), and to perform photoelectric conversion on the optical signal of the second reflector (7), and to output a weak current signal, thereby achieving coupling efficiency regulation.

4. The photoelectric detector with adjustable coupling efficiency according to claim 1, characterized in that: The chip side length of the piezoelectric micromirror (3) is 0.8 mm-1.5 mm; the diameter of the first reflector (6) is Φ0.5 mm-Φ1.2 mm; the rotation angle range of the first reflector (6) is ±2.4°; the driving voltage of the first reflector (6) is ≤5 V; and the rotation speed of the first reflector (6) is ≤5 ms.

5. The photoelectric detector with adjustable coupling efficiency according to claim 2, characterized in that: The circuit board ceramic substrate (10) is also provided with an amplifier circuit (11) for receiving the weak current signal output by the PIN chip (9), performing current-voltage conversion and three-stage amplification on the weak current signal, and outputting the amplified voltage signal.

6. The photoelectric detector with adjustable coupling efficiency according to claim 5, characterized in that: The tube shell (1) is provided with 8 signal pins, namely: a first pin (12), a second pin (13), a third pin (14), a fourth pin (15), a fifth pin (16), a sixth pin (17), a seventh pin (18) and an eighth pin (19); the first pin (12), the second pin (13), the third pin (14) and the fourth pin (15) are located on a long side of the tube shell (1) close to the second carrier (8); the fifth pin (16), the sixth pin (17), the seventh pin (18) and the eighth pin (19) are located on the other long side of the tube shell (1); The first pin (12) is a Vss interface, the second pin (13) is a first ground terminal, the third pin (14) is suspended, the fourth pin (15) is an output interface, the fifth pin (16) is a second ground terminal, the sixth pin (17) is a piezoelectric micromirror Vcc1 interface, the seventh pin (18) is a Vcc interface, and the eighth pin (19) is a piezoelectric micromirror Vss1 interface; the amplifying circuit (11) is connected to the signal pin by means of gold wire bonding.

7. The photoelectric detector with adjustable coupling efficiency according to claim 1, characterized in that: The optical fiber collimator (5) uses a C-lens as a collimating lens and is sealed with a metal tube.

8. The photoelectric detector with adjustable coupling efficiency according to claim 1, characterized in that: The distance between the PIN chip (9) and the second reflector (7) is 5 mm-15 mm.

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