A test method for integrated optical device used in front light path of fiber optic gyroscope

Abstract

The application relates to a kind of integrated optical device testing methods for fiber-optic gyroscope front light path, and the testing system includes first fiber coupler, second fiber coupler, fiber mirror, optical spectrum analyzer, optical power meter, extinction ratio tester and voltmeter, the light to be measured enters fiber mirror and second fiber coupler after being split by first fiber coupler, and second fiber coupler is connected to optical spectrum analyzer, optical power meter and extinction ratio tester respectively.After integrated optical device is powered on, the wavelength, spectral width and extinction ratio of integrated optical device can be directly obtained according to the readings of optical spectrum analyzer and extinction ratio tester.In addition, part of the light is returned to integrated optical device through first fiber coupler again after being returned by fiber mirror, and the output optical power value and optical responsivity value of integrated optical device can be calculated according to the readings of voltmeter and optical power meter, inherent insertion loss value of fiber coupler and inherent return loss value of fiber mirror.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing testing, specifically relating to a testing method for integrated optical devices used in the front optical path of a fiber optic gyroscope. Background Technology

[0002] Integrated optical components for the front optical path of fiber optic gyroscopes (hereinafter referred to as integrated optical components) are mainly used in integrated fiber optic gyroscopes. The integrated optical components contain SLD light-emitting diodes, optical lenses, Peltier coolers, PD photodiodes, amplifier circuits and fiber optic components. They have the functions of light emission, optical coupling / splitting and light detection, and can replace the three components of traditional fiber optic gyroscopes: SLD light source, fiber optic coupler and photodetector components.

[0003] The SLD (Light Emitting Diode) outputs a DC optical signal under external current drive. Part of the light is transmitted through the optical lens and coupled into the fiber optic assembly, then transmitted to the fiber optic gyroscope. The signal light returning from the gyroscope enters the same fiber optic cable as the integrated optical device. Part of the light is reflected at the optical lens and enters the PD (Photodiode) for photoelectric conversion, generating a current signal. This current signal is amplified by the amplifier circuit and converted into a voltage signal for output.

[0004] The wavelength, spectral width, extinction ratio, output optical power, and photoresponse of integrated optical devices are key indicators that significantly affect the performance of fiber optic gyroscopes and the reliability of the devices themselves, requiring screening tests before installation. Current technology requires inserting the pigtail of the integrated optical device into a spectrum analyzer, optical power meter, and extinction ratio tester to measure the corresponding parameter values. Additionally, fiber optic connections to external light source equipment are needed to test the photoresponse value, making the testing process cumbersome and inefficient. Summary of the Invention

[0005] The purpose of this invention is to provide a testing method for integrated optical devices used in the front optical path of a fiber optic gyroscope. By designing and combining a testing system and corresponding calculation methods, multiple indicators such as optical wavelength, spectral width, extinction ratio, output optical power, and optical responsivity of the integrated optical device can be obtained by performing only one fiber optic splice test, thereby improving the screening and testing efficiency in the actual production process.

[0006] Another objective of this invention is to provide an integrated optical device testing system for the front optical path of a fiber optic gyroscope.

[0007] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions:

[0008] A testing method for integrated optical devices used in the front optical path of a fiber optic gyroscope employs a combined testing system. The combined testing system includes a first fiber coupler, a second fiber coupler, a fiber optic mirror, a spectrometer, an optical power meter, an extinction ratio meter, and a voltmeter. One end of the first fiber coupler is connected to the integrated optical device under test, and the other end is connected to both the second fiber coupler and the fiber optic mirror. One end of the second fiber coupler is connected to the first fiber coupler, and the other end is connected to the spectrometer, optical power meter, and extinction ratio meter. The electrical output pin of the integrated optical device under test is connected to the voltmeter. The specific testing method includes the following steps:

[0009] (1) After the integrated optical device is powered on, the output optical signal enters the first fiber coupler. Part of the optical signal reaches the spectrum analyzer, optical power meter, and extinction ratio tester through the second fiber coupler. The remaining optical signal enters the fiber optic mirror, which returns part of the light, which then returns to the integrated optical device through the first fiber coupler. The wavelength λ and spectral width Δλ measured by the spectrum analyzer, the reading P of the optical power meter, the reading PER of the extinction ratio tester, and the reading U1 of the voltmeter are recorded. The output optical wavelength λ of the integrated optical device is recorded. DUT =λ, the spectral width Δλ output by the integrated optical device DUT =Δλ, Extinction ratio PER of integrated optical devices DUT =PER;

[0010] (2) Calculate the output optical power value P of the integrated optical device based on the measurement results of step (1). DUT The calculation formula is as follows:

[0011] P DUT =P+IL 12 +IL 46

[0012] Among them: IL 12 The inherent insertion loss value IL represents the connection point from the port of the integrated optical device connected to the first fiber coupler to the port of the second fiber coupler. 46 The inherent insertion loss value for connecting the port of the first fiber coupler to the port of the optical power meter via the second fiber coupler;

[0013] (3) Based on P obtained in step (2) DUT The optical power value returned to the integrated optical device is calculated using the following formula:

[0014] P in =P DUT -2×IL 13 -RL

[0015] Among them: IL 13Let RL be the inherent insertion loss of the first fiber coupler from the port connecting the integrated optical device to the port connecting the fiber mirror, and let RL be the inherent return loss of the fiber mirror.

[0016] (4) Disconnect the integrated optical device's fiber optic cable from port 1 of the test device, and perform anti-reflection treatment at the end of the integrated optical device's fiber optic cable. Record the voltmeter reading U0, and calculate the optical responsivity value R of the integrated optical device based on the optical power value in step (3). e The calculation formula is as follows:

[0017]

[0018] The first fiber coupler, the second fiber coupler, and the fiber reflector are connected by fusion splicing using a fusion splicer.

[0019] One end of the second fiber optic coupler includes three ports: 5, 6, and 7. The connection methods between ports 5, 6, and 7 and the spectrometer, optical power meter, and extinction ratio tester are as follows: ports 5, 6, and 7 of the second fiber optic coupler are fused to FC / APC single-mode fiber optic patch cords, and the FC / APC connectors of ports 5, 6, and 7 are respectively inserted into the spectrometer, optical power meter, and extinction ratio tester.

[0020] The integrated optical device is connected to the first fiber coupler in the following way: about 1 meter of bare optical fiber is reserved at the port of the first fiber coupler connected to the integrated optical device, and the pigtail of the integrated optical device is fused to the bare optical fiber at port 1.

[0021] A test system for integrated optical devices used in the front optical path of a fiber optic gyroscope includes a first fiber coupler, a second fiber coupler, a fiber optic mirror, a spectrum analyzer, an optical power meter, an extinction ratio tester, and a voltmeter, wherein:

[0022] The first fiber coupler receives the optical signal from the integrated optical device under test and outputs it to the second fiber coupler and the fiber mirror respectively. It also receives the optical signal returned by the fiber mirror and outputs it to the integrated optical device under test.

[0023] The second fiber optic coupler receives the optical signal from the first fiber optic coupler and outputs it to the spectrum analyzer, optical power meter and extinction ratio tester, respectively.

[0024] The fiber optic mirror receives the optical signal input from the first fiber optic coupler and returns a portion of the optical signal back to the first fiber optic coupler.

[0025] A spectrometer is used to measure the wavelength and spectral width of received optical signals;

[0026] An optical power meter is used to measure the optical power value of a received optical signal.

[0027] An extinction ratio tester is used to measure the extinction ratio of a received optical signal.

[0028] A voltmeter is used to measure the voltage value of an integrated optical device under test.

[0029] It also includes a housing, and the first fiber coupler, the second fiber coupler, the fiber reflector, and the fiber connecting the above devices are disposed inside the housing.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] This invention uses a test system structure test to obtain parameters such as wavelength, spectral width, extinction ratio, output optical power, and photoresponse of integrated optical devices with only one fusion test, avoiding multiple connection tests. It is simple, efficient, and fast to operate. Attached Figure Description

[0032] Figure 1 This is a schematic diagram for testing integrated optical devices. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0034] like Figure 1 The diagram shows a test schematic of an integrated optical device. The first fiber coupler has one input port and two output ports. Light enters from port 1, is split, and exits from ports 2 and 3, with corresponding inherent insertion loss values ​​of IL. 12 and IL 13 Its spectral bandwidth is greater than the spectral width output by the integrated optical device, and its absolute value of polarization crosstalk is greater than the extinction ratio of the integrated optical device.

[0035] The second fiber coupler has one input port and three output ports. Light output from port 2 of the first fiber coupler enters port 4 of the second fiber coupler, and after being split, is output from ports 5, 6, and 7, with corresponding intrinsic insertion loss values ​​of IL. 45 IL 46 IL 47 Its spectral bandwidth is greater than the spectral width output by the integrated optical device, and its absolute value of polarization crosstalk is greater than the extinction ratio of the integrated optical device.

[0036] The fiber optic mirror can reflect light back, and its inherent return loss value is RL. The light output from port 3 of the first fiber coupler enters the fiber optic mirror, is reflected back to port 3 of the first fiber coupler, is then output from port 1, and finally returns to the integrated optical device as the input light of the integrated optical device.

[0037] The specific testing method includes the following steps:

[0038] (1) After the integrated optical device is powered on, the output optical signal enters the first fiber coupler, enters the second fiber coupler through port 2, and then reaches the spectrometer, optical power meter and extinction ratio tester. It enters the fiber reflector through port 3, and the fiber reflector returns part of the light. It then returns to the integrated optical device through the first fiber coupler and records the measurement results of the spectrometer, optical power meter and extinction ratio tester and voltmeter.

[0039] (2) Calculate the output optical power value P of the integrated optical device based on the measurement results of step (1). DUT The unit is dBm, and the calculation formula is as follows:

[0040] P DUT =P+IL 12 +IL 46

[0041] Where: P is the optical power meter reading, in dBm; IL 12 The intrinsic insertion loss value from port 1 to port 2 of the first fiber coupler, in dB, IL. 46 This represents the inherent insertion loss value from port 4 to port 6 of the second fiber coupler, in dB.

[0042] (3) Calculate the optical power value P returned to the integrated optical device. in The unit is dBm, and the calculation formula is as follows:

[0043] P in =P DUT -2×IL 13 -RL

[0044] Where: P DUT The output optical power of the integrated optical device, in dBm, is calculated in step (2); IL 13 RL represents the inherent insertion loss of the first fiber coupler from port 1 to port 3, in dB; RL represents the inherent return loss of the fiber mirror, in dB.

[0045] (4) Disconnect the integrated optical device's fiber optic pigtail from port 1 of the test device, perform anti-reflection treatment at the end of the integrated optical device's fiber optic pigtail, record the voltage value of the voltmeter, and calculate the optical responsivity value R of the integrated optical device based on the measurement results. e The unit is V / μW, and the calculation formula is as follows:

[0046]

[0047] Where: U1 is the voltmeter reading measured in step (1), in V; U0 is the voltmeter reading measured in step (4), in V; Pin The optical power value of the integrated optical device, in μW, is calculated in step (3) and converted into absolute optical power.

[0048] (5) The wavelength λ and spectral width of the output light at port 5 measured by the spectrometer in step (1) are...

[0049] Δλ, because the spectral bandwidth of the fiber coupler is greater than the spectral width of the output light from the integrated optical device, the wavelength λ of the output light from the integrated optical device is... DUT =λ, the spectral width Δλ output by the integrated optical device DUT =△λ; The extinction ratio PER of the 7-port output light was measured by the extinction ratio tester. Since the absolute value of the polarization crosstalk of the fiber coupler is greater than the extinction ratio of the output light of the integrated optical device, the extinction ratio PER of the integrated optical device is... DUT =PER.

[0050] Example 1

[0051] One 1×2 fiber optic coupler, one 1×3 fiber optic coupler, and one fiber optic mirror were selected in the 1310nm band. The inherent insertion loss IL between port 1 and ports 2 and 3 of the 1×2 fiber optic coupler is... 12 IL 13 The values ​​are 3.20 dB and 3.37 dB respectively, with a spectral bandwidth of 80 nm and an absolute polarization crosstalk of 14 dB; the inherent insertion loss IL between port 4 and ports 5, 6, and 7 of the 1×3 fiber coupler is... 45 IL 46 IL 47 The values ​​are 5.25dB, 4.87dB, and 5.36dB respectively, with a spectral bandwidth of 80nm and an absolute polarization crosstalk of 12dB; the inherent return loss RL of the fiber optic mirror is 13.01dB, which means the reflectivity is 5.0%.

[0052] Two fiber optic couplers and one fiber optic reflector were fused together using a fusion splicer. Ports 5, 6, and 7 were fused with FC / APC single-mode fiber optic patch cords. The loss value at each splice point was less than 0.01dB, and the splice point loss value can be ignored in subsequent calculations.

[0053] A test device is constructed by fixing the first fiber coupler, the second fiber coupler, the fiber reflector, and the fiber connecting the above devices in a single housing. Approximately 1 meter of bare fiber is reserved at port 1. The FC / APC connectors at ports 5, 6, and 7 are respectively inserted into a spectrometer, an optical power meter, and an extinction ratio tester, thus establishing a fixed test system.

[0054] The integrated optical device's pigtail is fused to port 1 of the test device, with a fusion loss of less than 0.01dB. The output pin of the integrated optical device is connected to a voltmeter.

[0055] Develop a set of testing software to control each instrument to perform testing operations. The software collects the readings of the spectrometer: λ = 1305.6nm, Δλ = 35.6nm, P = -12.01dBm, PER = 0.8dB, and U1 = -0.817V.

[0056] Disconnect the integrated optical device's fiber optic pigtail from port 1 of the test device (point C in the attached diagram), and perform anti-reflection treatment at the end of the integrated optical device's fiber optic pigtail to prevent light from entering the integrated optical device. At this time, the software acquires the voltmeter reading U0 as -1.657V. Finally, the software automatically calculates the wavelength λ of the light output from the integrated optical device according to the formula. DUT The wavelength is 1305.6 nm, and the spectral width is Δλ. DUT 35.6nm, extinction ratio PER DUT 0.8dB, output optical power value P DUT -3.94 dBm, photoresponse value R e It is 0.196V / μW.

[0057] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0058] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for testing integrated optical devices used in the front optical path of a fiber optic gyroscope, characterized in that: A combined testing system is used for testing. This system includes a first fiber optic coupler, a second fiber optic coupler, a fiber optic mirror, a spectrometer, an optical power meter, an extinction ratio meter, and a voltmeter. One end of the first fiber optic coupler is connected to the integrated optical device under test, and the other end is connected to the second fiber optic coupler and the fiber optic mirror. One end of the second fiber optic coupler is connected to the first fiber optic coupler, and the other end is connected to the spectrometer, optical power meter, and extinction ratio meter. The electrical output pin of the integrated optical device under test is connected to the voltmeter. The specific testing method includes the following steps: (1) After the integrated optical device is powered on, the output optical signal enters the first fiber coupler. Part of the optical signal reaches the spectrum analyzer, optical power meter and extinction ratio tester through the second fiber coupler. The remaining optical signal enters the fiber mirror. The fiber mirror returns part of the light, and then returns to the integrated optical device through the first fiber coupler. The wavelength λ and spectral width Δλ measured by the spectrum analyzer, the reading P of the optical power meter, the reading PER of the extinction ratio tester and the reading U1 of the voltmeter are recorded. The wavelength λ of the light output by the integrated optical device is recorded. DUT =λ, the spectral width Δλ output by the integrated optical device DUT =△λ, Extinction ratio of integrated optical devices PER DUT =PER; (2) Calculate the output optical power value P of the integrated optical device based on the measurement results of step (1). DUT The calculation formula is as follows: Among them: IL 12 The inherent insertion loss value IL represents the connection point from the port of the integrated optical device connected to the first fiber coupler to the port of the second fiber coupler. 46 The inherent insertion loss value for connecting the port of the first fiber coupler to the port of the optical power meter via the second fiber coupler; (3) Based on P obtained in step (2) DUT Calculate and return the optical power value to the integrated optical device. The calculation formula is as follows: Among them: IL 13 Let RL be the inherent insertion loss of the first fiber coupler from the port connecting the integrated optical device to the port connecting the fiber mirror, and let RL be the inherent return loss of the fiber mirror. (4) Disconnect the integrated optical device pigtail from port 1 of the test device, and perform anti-reflection treatment at the end of the integrated optical device pigtail. Record the voltmeter reading U0, and determine the optical power value according to step (3). Calculate the optical responsivity R of the integrated optical device e The calculation formula is as follows: 。 2. The method for testing integrated optical devices in the front optical path of a fiber optic gyroscope according to claim 1, characterized in that: The first fiber coupler, the second fiber coupler, and the fiber reflector are connected by fusion splicing using a fusion splicer.

3. The method for testing integrated optical devices in the front optical path of a fiber optic gyroscope according to claim 1, characterized in that: One end of the second fiber optic coupler includes three ports: 5, 6, and 7. The connection methods between ports 5, 6, and 7 and the spectrometer, optical power meter, and extinction ratio tester are as follows: ports 5, 6, and 7 of the second fiber optic coupler are fused to FC / APC single-mode fiber optic patch cords, and the FC / APC connectors of ports 5, 6, and 7 are respectively inserted into the spectrometer, optical power meter, and extinction ratio tester.

4. The method for testing integrated optical devices in the front optical path of a fiber optic gyroscope according to claim 1, characterized in that: The integrated optical device is connected to the first fiber coupler in the following way: about 1 meter of bare optical fiber is reserved at the port of the first fiber coupler connected to the integrated optical device, and the pigtail of the integrated optical device is fused to the bare optical fiber at port 1.

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