Detector test system based on photodiode

Abstract

The utility model discloses a photodiode-based detector test system, and relates to the technical field of fiber-optic gyroscopes, a photodiode is used for building a detector module, and the photodiode-based detector test system comprises an SLD light source, a light source driving board, a 2 * 2 coupler, a Y waveguide, a fiber-optic ring, a photodiode, a PD pre-amplification board and a detector signal demodulation board, compared with a traditional detector module, the size of the fiber-optic gyroscope can be reduced, the use cost can be effectively reduced, and meanwhile the use flexibility is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fiber-optic gyroscope, and particularly relates to a detector testing system based on photodiode. BACKGROUND

[0002] The fiber-optic gyroscope works based on Sagnac effect, has the characteristics of small volume and strong anti-interference ability, and is widely used in the fields of missiles, submarines and rockets.

[0003] The common fiber-optic gyroscope on the market is shown in the accompanying drawings Figure 1 As shown in the drawings, it is composed of two parts of optical path and circuit, the optical path part includes SLD light source, 2*2 coupler, Y waveguide, fiber ring and detector assembly, the light emitted from the SLD light source is divided into two beams after the coupler and Y waveguide, the two beams propagate along clockwise and counterclockwise in the fiber ring, then the interference occurs again on the Y waveguide, the interference light contains Sagnac phase shift caused by carrier rotation, the interference light reaches the detector assembly through the coupler, and the detector assembly converts the optical signal into electrical signal; the circuit part includes mainboard, the mainboard receives the electrical signal output by the detector assembly, amplifies, filters and demodulates the electrical signal, and calculates the carrier rotation angular velocity.

[0004] The detector assembly is an important part of the fiber-optic gyroscope system, which is responsible for converting the interference signal generated by Sagnac into electrical signal, and amplifying the signal, and the amplified electrical signal can obtain the carrier angular velocity after subsequent signal processing. In the fiber-optic gyroscope, PIN-FIT detector assembly is usually used, because of its large volume, high price and non-adjustable parameters, it is not friendly in the aspects of fiber-optic gyroscope miniaturization, use flexibility and cost control, and it is not suitable for use in the process of fiber-optic gyroscope mass production, so it is necessary to use PD photodiode and build an amplification circuit to realize the function of the detector, which can effectively reduce the volume of the fiber-optic gyroscope, increase the use flexibility and save the cost. SUMMARY

[0005] Therefore, the present application provides a detector testing system based on photodiode, which uses photodiode detector instead of common PIN-FIT detector assembly, can effectively reduce the volume of fiber-optic gyroscope, increase the use flexibility and save the cost.

[0006] A detector testing system based on photodiode, comprising SLD light source, light source driving board, 2*2 coupler, Y waveguide and fiber ring, the light source driving board is used for driving the SLD light source to generate light source; the SLD light source, 2*2 coupler, Y waveguide and fiber ring are connected in sequence, and further comprising: photodiode, PD preamplifier board and detector signal demodulation board.

[0007] The photodiode and the SLD light source are connected to different interfaces on the same side of the 2*2 coupler respectively, and the photodiode is welded with the PD preamplifier board through the fixed hole position on the PD preamplifier board.

[0008] There are two groups of fixed hole positions on the detector signal demodulation board, which are used for plugging with the PD preamplifier board or the external detector.

[0009] Further, the responsivity of the photodiode is 0.9.

[0010] Further, the length of the optical fiber ring is 250m.

[0011] Further, the replaceable filter capacitor is installed on the PD preamplifier board, and the size of the filter capacitor is 1pF.

[0012] Further, the external detector adopts a PIN-PET detector assembly.

[0013] Further, the SLD light source is connected to the light source driving board by welding.

[0014] Further, the detector signal demodulation board and the light source driving board are connected by wire.

[0015] Beneficial effects:

[0016] 1. The present application provides a photodiode-based detector test system, which can reduce the size of the fiber-optic gyroscope and effectively reduce the use cost by using photodiodes to build a detector module.

[0017] 2. In the present application, the replaceable filter capacitor is installed on the PD preamplifier board, and the filter effect of the amplifier can be changed by changing the capacitor on the PD preamplifier board. Since the parameters are adjustable, the input power range of the detector can be expanded, and the flexibility of use is higher.

[0018] 3. In the present application, the detector signal demodulation board has two groups of fixed hole positions, which can be plugged with the PD preamplifier board and the PIN-FET detector assembly respectively, so as to realize the performance test comparison of the PD photodiode and the PIN-FIT detector assembly under the same conditions.

[0019] 4. In the present application, the SLD light source is connected to the light source driving board by welding, which ensures the reliability of the connection.

[0020] 5. In the present application, the detector signal demodulation board and the light source driving board are connected by wire, which ensures the stability of signal transmission. DETAILED DESCRIPTION

[0021] Figure 1 It is a schematic diagram of a common fiber-optic gyroscope system.

[0022] Figure 2 It is a schematic diagram of the system scheme of the embodiment of the application.

[0023] Figure 3 It is a schematic diagram of the PD preamplifier board of the embodiment of the application. DETAILED DESCRIPTION

[0024] The application will be described in detail below with reference to the drawings and embodiments.

[0025] In view of the problems of large volume, high price and non-adjustable parameters of the current detector assembly, the application provides a detector testing system based on a photodiode. Figure 2 As shown in the figure, the system includes an SLD light source, a light source driving board, a 2*2 coupler, a Y waveguide, a fiber ring, a photodiode, a PD preamplifier board and a main board (the main board in the embodiment is a detector signal demodulation board).

[0026] The light source driving board is used to drive the SLD light source to generate a light source; the SLD light source, the 2*2 coupler, the Y waveguide and the fiber ring are connected in sequence, the photodiode is connected to different interfaces on the same side of the 2*2 coupler respectively, and the photodiode is welded with the PD preamplifier board through the fixed hole position on the PD preamplifier board; the detector signal demodulation board has two or more fixed hole positions for plugging with the PD preamplifier board or an external detector.

[0027] The light emitted from the SLD light source is divided into two beams after the coupler and the Y waveguide, the two beams propagate along the clockwise and counterclockwise directions in the fiber ring respectively, and then the two beams meet again on the Y waveguide to interfere, the interference light contains the Sagnac phase shift caused by the carrier rotation, and the interference light reaches the photodiode and the PD preamplifier board through the coupler.

[0028] The 2*2 coupler and the Y waveguide are used as light splitting devices and also bear the signal transmission after interference; the fiber ring is used for transmitting optical signals; the photodiode and the PD preamplifier board are used to convert the photocurrent signal into a voltage signal and amplify the signal, the transimpedance on the PD preamplifier board can be changed according to the output power requirement, and the filter capacitor on the PD preamplifier board can be changed according to the frequency requirement; the detector signal demodulation board is used to isolate the direct current, amplify and calculate the voltage signal converted by the photodiode and the PD preamplifier board, and also supply power to the power driving board through wired connection.

[0029] Further, the SLD light source can be connected to the light source driving board by welding. The driving resistance on the light source driving board is adjustable. The detector signal demodulation board and the light source driving board can be connected by wire.

[0030] In the embodiment, since the light powers of different fiber optic gyroscope systems reaching the detector are different, the transimpedance on the amplification board can be changed according to the power size and the detector output voltage. Taking a 250m long fiber ring as an example, the peak-to-peak voltage of the modulated signal reaching the detector needs to be 2V. The responsivity of the photodiode in the application is 0.9. The relationship between the voltage value V reaching the detector and the light power W reaching the detector and the transimpedance R is V=0.9×W×R. Therefore, when the light power reaching the detector is 10μW, the transimpedance needs to be 400KΩ. When the light power reaching the detector is 20μW, the transimpedance needs to be 200KΩ. The filter capacitance on the PD preamplification board can also be changed according to the frequency. When the length of the fiber ring is 250m and the transimpedance is 400KΩ, the working frequency of the gyroscope is about 380KHz. According to the filter frequency f=1 / (2πRC), it can be calculated that the filter capacitance is about 1pF. Therefore, when the length of the fiber ring is different, the working frequency of the gyroscope is different, and the filter capacitance is also different, realizing the adjustable capacitance. The SLD light source is welded to the light source driving board, which is used to provide driving current for the SLD light source. When the light source power is too large or too small, the light power reaching the detector will be too large or too small. At this time, the transimpedance value can be adjusted to ensure that the output voltage of the detector meets the requirements. The detector signal demodulation board performs direct current isolation, amplification and signal processing and calculation on the voltage signal output by the detector. The detector signal demodulation board has a fixed hole solder pad, which is specially used for plug-in with the PD preamplification board, and can also be plugged in with the PIN-FIT detector assembly in the dashed box. The output waveforms of the PD photodiode and the PIN-FIT detector assembly can be compared in the same condition through an oscilloscope. At the same time, the performance indicators of the fiber optic gyroscope in two conditions can be compared through the fiber optic gyroscope host computer test software. The principle of the PD preamplification board of the embodiment of the application is shown in Figure 3 .

[0031] In summary, the above is only a preferred embodiment of the application, and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A photodiode-based probe testing system, comprising an SLD light source, a light source driving board, a 2*2 coupler, a Y waveguide and a fiber ring, the light source driving board being used to drive the SLD light source to generate a light source; the SLD light source, the 2*2 coupler, the Y waveguide and the fiber ring being connected in sequence, characterized in that, Also include: Photodiode, PD preamplification board and detector signal demodulation board; Wherein, the photodiode and SLD light source are connected with different interfaces on the same side of 2×2 coupler, the photodiode is welded with the PD preamplification board through the fixed hole position on the PD preamplification board; The detector signal demodulation board has two groups of fixed hole positions, which are used for plug-in with the PD preamplification board or external detector.

2. The system of claim 1, wherein, The responsivity of the photodiode is 0.

9.

3. The system of claim 1 or 2, wherein, The length of the optical fiber ring is 250m.

4. The system of claim 3, wherein, The PD preamplification board is provided with replaceable filter capacitor, and the size of the filter capacitor is 1pF.

5. The system of claim 4, wherein, The external detector adopts PIN-PET detector assembly.

6. The system of claim 4 or 5, wherein, The SLD light source is connected with the light source driving board by welding.

7. The system of claim 6, wherein, The detector signal demodulation board and the light source driving board are connected by wire.

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