Fiber-optic gyroscope light source with high power stability

Abstract

The utility model discloses a fiber-optic gyroscope light source with high power stability. The fiber-optic gyroscope light source comprises a pumping source, a light path module and a control module, the pumping source comprises a photodiode and a laser chip, and the photodiode and the laser chip are packaged on a thermoelectric cooling device TEC; one part of light output by the laser chip in the pumping source forms an ASE light source through the light path module, and the other part of light enters the photodiode through the light path module. According to the utility model, the problem that the optical fiber gyroscope light source is easily influenced by external environment temperature is solved, and high power stability and high average wavelength stability in a full temperature range can be ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of fiber optic gyroscope manufacturing, in particular to a fiber optic gyroscope light source with high power stability. Background Art

[0002] As the signaling device of the fiber optic gyroscope, the performance of the light source has a great influence on the measurement accuracy of the fiber optic gyroscope. At present, the 1550nm band erbium-doped fiber light source is commonly used in high-precision fiber optic gyroscopes. Compared with the commonly used flat spectrum light source, the Gaussian spectrum erbium-doped fiber light source has better spectral symmetry, so the spectrum stability is less affected by ambient temperature changes and pump power fluctuations; at the same time, its self-coherence is lower and the coherence length is shorter, which can effectively reduce the phase error of the fiber optic gyroscope, so it is more suitable for use in high-precision fiber optic gyroscopes.

[0003] The current mainstream fiber gyro light source solution uses semiconductor radiation sources such as DFB butterfly lasers as pumps for ASE (amplified spontaneous emission) light sources, obtains power output through a two-way optical path, and uses a PIN tube at the back end to detect the ASE light source power. The output optical power is detected and adjusted in real time through a feedback loop to ensure the stability of the optical power.

[0004] Usually, fiber optic gyroscopes need to meet the requirements of a wide operating environment temperature, which is -45℃~70℃ (hereinafter referred to as the full temperature range). As a semiconductor device, the working principle of the PIN tube is that photogenerated carriers generate current under the action of a bias electric field, and the photoelectric sensitivity is affected by the device temperature. Within the full temperature range, the photosensitivity of the PIN tube will change. Although there are currently solutions to compensate for it, it will still cause the error of the power feedback loop to increase, resulting in a large change in the final ASE light source optical power, affecting the overall performance of the gyroscope. Therefore, it is necessary to design a special PIN tube and light source optical path to meet the needs of a high-power stability fiber optic gyroscope. Utility Model Content

[0005] In order to solve the above technical problems, the purpose of the utility model is to provide a fiber optic gyroscope light source with high power stability, which solves the difficult problem that the fiber optic gyroscope light source is easily affected by the external ambient temperature and can ensure high power stability and high average wavelength stability within the full temperature range.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0007] A high-power stable fiber gyro light source comprises a pump source, an optical path module and a control module; the pump source comprises a photodiode and a laser chip, and the photodiode and the laser chip are packaged on a thermoelectric cooling device TEC; part of the light output by the laser chip in the pump source forms an ASE light source through the optical path module, and part of the light enters the photodiode through the optical path module.

[0008] Furthermore, a heat sink is provided on the thermoelectric cooling device TEC, and the photodiode and the laser chip are arranged on the heat sink.

[0009] Furthermore, a waveguide partition is provided between the photodiode and the laser chip.

[0010] Furthermore, the photodiode and the laser chip are parallel to each other, and the pump source also includes a first focusing lens, a dichroic mirror, a coupling lens, a coupling optical fiber, which are sequentially arranged on the optical axis of the laser chip, a second focusing lens coaxial with the photodiode, and a return light reflector arranged on the optical axis of the second focusing lens.

[0011] Furthermore, the optical path module includes a double-pass structure optical path and a coupler, the double-pass structure optical path includes an active optical fiber and a double-pass reflector, the active optical fiber is connected to the single end of the coupler, and the spontaneous radiation light emitted by the active optical fiber is reflected by the double-pass reflector; one arm of the double-root end of the coupler is connected to the pump source, and the other arm is connected to the isolator, and the output end of the isolator is connected to the filter.

[0012] Furthermore, the control module includes a controller and a driving module and a temperature control module connected to the controller through signals. The driving module includes a DA converter, a comparator and a MOSFET driving circuit. The photodiode is connected to the controller signal. A part of the light enters the photodiode. The output current of the photodiode is converted into a voltage signal. After comparison with the reference voltage, a negative feedback signal is generated to control the driving current of the laser chip in the pump source; the temperature control module includes a preamplifier, a temperature control chip and an H-bridge circuit. The preamplifier amplifies the temperature signal. The controller starts to control the temperature control chip and outputs current to drive the thermoelectric cooling device TEC through the H-bridge circuit.

[0013] Furthermore, the laser chip is selected from DFB, EEL or VCSEL chips using a wavelength of 980nm, 1550nm or 915nm.

[0014] Furthermore, the photodiode is selected from a PIN type or an APD type.

[0015] The beneficial effects of the utility model are:

[0016] The utility model uses TEC to control the temperature of the photodiode by packaging the photodiode and the laser chip together on the thermoelectric cooling device TEC. At the same time, a unique packaging optical path structure is designed to isolate the emitted light of the laser chip from the photodiode to ensure that the active devices do not affect each other.

[0017] The utility model can maintain the photoelectric sensitivity high stability of the photodiode used for optical power feedback control within the full temperature range, ensure the temperature of the photodiode is constant, and ensure the stable operation of the power feedback loop.

[0018] The utility model solves the problem that the fiber optic gyroscope light source is easily affected by the external ambient temperature, and can obtain a light source with high power stability and high average wavelength stability within the full temperature range; and the light source of the utility model has a simple optical path structure, a small number of components, low difficulty in production implementation, and is easy for semiconductor packaging, which is conducive to engineering batch application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a principle diagram of the optical path of a high-power stable fiber optic gyro light source according to an embodiment of the utility model.

[0020] Figure 2 It is a schematic diagram of the pump source packaging structure in an embodiment of the utility model.

[0021] Figure 3 It is a block diagram of the working principle of an embodiment of the utility model.

[0022] In the figure, 1: photodiode; 2: laser chip; 3: thermoelectric cooling device TEC; 4: partition in waveguide; 5: first focusing lens; 6: dichroic mirror; 7: coupling lens; 8: coupling optical fiber; 9: second focusing lens; 10: return light reflector; 11: coupler; 12: active optical fiber; 13: double-pass reflector; 14: isolator; 15: filter. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0024] like Figures 1 to 3 A high-power stable fiber gyro light source is shown, comprising a pump source, an optical path module and a feedback control module.

[0025] The pump source includes a photodiode 1 and a laser chip 2, and the photodiode 1 and the laser chip 2 are packaged on a thermoelectric cooling device TEC 3; specifically, a heat sink is provided on the thermoelectric cooling device TEC 3, and the photodiode 1 and the laser chip 2 are arranged on the heat sink. A waveguide partition 4 is provided between the photodiode 1 and the laser chip 2. The provision of the waveguide partition 4 can minimize the influence of the light emitted by the laser chip on the photodiode.

[0026] The photodiode 1 and the laser chip 2 are parallel to each other, and the pump source further includes a first focusing lens 5, a dichroic mirror 6, a coupling lens 7, a coupling optical fiber 8, which are sequentially arranged on the optical axis of the laser chip, a second focusing lens 9 coaxial with the photodiode 1, and a return light reflector 10 arranged on the optical axis of the second focusing lens 9. The dichroic mirror 6 and the return light reflector 10 are both arranged at an inclination of 45°.

[0027] The laser chip 2 is selected from DFB, EEL or VCSEL chips using a wavelength of 980nm, 1550nm or 915nm. The photodiode 1 is selected from PIN type or APD type.

[0028] The optical path module includes a double-pass structure optical path and a coupler 11, the double-pass structure optical path includes an active optical fiber 12 and a double-pass reflector 13, the active optical fiber 12 is connected to a single end of the coupler 11, and the spontaneous radiation light emitted by the active optical fiber 12 is reflected by the double-pass reflector 13; one arm of the double-root end of the coupler 11 is connected to the pump source, and the other arm is connected to the isolator 14, and the output end of the isolator 14 is connected to the filter 15.

[0029] The emission light output by the laser chip 2 is output to the active optical fiber 12 through the coupler 11 as a pump source. The active optical fiber 12 in a high energy state generates spontaneous emission amplified light through a double-pass structure optical path. Along the splitting direction of the coupler 11, a part of it enters the butterfly-packaged photodiode 1 along the optical path, and the other part enters the subsequent optical fiber optical path, passes through the isolator 14 and the filter 15, and the pigtail of the filter 15 outputs the target light to form a stable ASE light source.

[0030] The laser output and the receiving laser share a coupling lens 7 and a coupling optical fiber 8, and a dichroic mirror 6 is used to separate the emission light and the return light at the mirror surface, so that the return light enters the photodiode 1 along the optical path.

[0031] like Figure 3As shown, the control module includes a controller and a driving module and a temperature control module connected to the controller through signals. The driving module includes a DA converter, a comparator and a MOSFET driving circuit. The photodiode is connected to the controller by signal. A part of the light enters the photodiode. The output current of the photodiode is converted into a voltage signal. After comparison with the reference voltage, a negative feedback signal is generated to control the driving current of the laser chip in the pump source; the temperature control module includes a preamplifier, a temperature control chip and an H-bridge circuit. The temperature control module uses a temperature sensor to obtain the real-time working environment temperature of the laser chip and the photodiode; the controller can set a preset temperature; the actual temperature is compared with the preset temperature to form a feedback signal, and the preamplifier amplifies the signal; the controller starts to control the temperature control chip, and through the H-bridge circuit, the output current drives the thermoelectric cooling device TEC to achieve heating or cooling.

[0032] In the utility model, the isolator outputs a C-band wide spectrum light source, and a 15nm bandwidth filter is used to select a light source with a 1530nm peak or a 1560nm peak. Since the photoelectric conversion effect of the photodiode is affected by temperature, within the full temperature range of -45°C to 75°C, the photosensitivity change of the photodiode is 3%, and the power fluctuation of the ASE light source is 3%. After using TEC to control the temperature of the photodiode, the influence of temperature is eliminated, and the power stability of the ASE light source is improved to 0.5%, which correspondingly improves the average spectral stability, meets the light source requirements of medium and high precision fiber optic gyroscopes, and can improve indicators such as the calibration factor and data accuracy of the fiber optic gyroscope.

[0033] The utility model monitors the voltage output by the photodiode and adjusts the current of the laser chip through feedback control so that the voltage of the photodiode remains stable, that is, the power of the laser chip is controlled by feedback to maintain the stability of the output power of the ASE light source. At the same time, the output current of the temperature control module drives the TEC to heat or cool, ensuring that the temperature of the photodiode and the laser chip is constant.

[0034] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high power stable fiber optic gyro light source, characterized in that: It includes a pump source, an optical path module and a control module; the pump source includes a photodiode and a laser chip, and the photodiode and the laser chip are packaged on a thermoelectric cooling device TEC; part of the light output by the laser chip in the pump source forms an ASE light source through the optical path module, and part of the light enters the photodiode through the optical path module.

2. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: A heat sink is provided on the thermoelectric cooling device TEC, and the photodiode and the laser chip are arranged on the heat sink.

3. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: A waveguide partition is provided between the photodiode and the laser chip.

4. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: The photodiode and the laser chip are parallel to each other. The pump source also includes a first focusing lens, a dichroic mirror, a coupling lens, a coupling optical fiber, which are sequentially arranged on the optical axis of the laser chip, a second focusing lens coaxial with the photodiode, and a return light reflector arranged on the optical axis of the second focusing lens.

5. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: The optical path module comprises a double-pass structure optical path and a coupler, wherein the double-pass structure optical path comprises an active optical fiber and a double-pass reflector, wherein the active optical fiber is connected to a single end of the coupler, and the spontaneous radiation light emitted by the active optical fiber is reflected by the double-pass reflector; one arm of the double-end of the coupler is connected to the pump source, and the other arm is connected to an isolator, and the output end of the isolator is connected to a filter.

6. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: The control module includes a controller and a driving module and a temperature control module connected to the controller through signals. The driving module includes a DA converter, a comparator and a MOSFET driving circuit. The photodiode is connected to the controller signal. A part of the light enters the photodiode. The output current of the photodiode is converted into a voltage signal. After comparison with the reference voltage, a negative feedback signal is generated to control the driving current of the laser chip in the pump source; the temperature control module includes a preamplifier, a temperature control chip and an H-bridge circuit. The preamplifier amplifies the temperature signal. The controller starts to control the temperature control chip and outputs current to drive the thermoelectric cooling device TEC through the H-bridge circuit.

7. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: The laser chip is selected from DFB, EEL or VCSEL chips using a wavelength of 980nm, 1550nm or 915nm.

8. The fiber optic gyro light source with high power stability according to claim 1, characterized in that: The photodiode is selected from a PIN type or an APD type.

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