Calibration device and calibration method for extinction ratio tester with wide adjustable extinction ratio

Abstract

The present invention relates to an extinction ratio tester calibration device with an adjustable extinction ratio in a wide range, which comprises a first light source with adjustable power, a second light source with adjustable power, a first polarizer, a second polarizer and a beam combining device, wherein the first polarizer is arranged on the optical path of the light emitted by the first light source, the second polarizer is arranged on the optical path of the light emitted by the second light source, and the light emitted by the first light source passes through the first polarizer and is combined with the light emitted by the second light source passing through the second polarizer in the beam combining device into a beam of light containing a pair of orthogonal polarized lights. The present invention adopts different independent lasers to work separately, can be applicable to narrow spectrum lasers, can perform more accurate calibration for extinction ratio testers in special application fields, and can control the working states of the two light sources separately, has a two-stage polarizer, can realize continuous adjustment of polarization degree in the range of 0-60dB, can also arbitrarily open a component of a certain polarization state, can use a common optical power meter to perform accurate power measurement, thereby determining the polarization state of the output light.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber sensing, in particular to a calibration device and a calibration method for an extinction ratio tester with an adjustable extinction ratio in a wide range. Background Art

[0002] With the maturity of the technology of polarization-maintaining optical fiber and other polarization-maintaining devices, both sensor systems and optical communication systems are gradually adopting optical polarization-maintaining solutions, which greatly benefits the sensor sensitivity and communication capacity, and greatly improves the performance. At this time, it becomes necessary to measure the polarization-maintaining ability of the device. The most common polarization-maintaining ability measurement equipment is the polarization extinction ratio tester, also called the polarization crosstalk tester. Its measurement principle is to convert the measured light signal into an electrical signal through a spatial method after it is collimated by a lens and then incident on a photodetector through a polarizer, where the polarizer rotates to detect the size of the light components in different polarization directions. This type of equipment is affected by the stress birefringence of the lens, the polarization analysis ability of the polarizer, and the polarization responsivity of the detector. There is a high uncertainty in the test of extremely high extinction ratio and extremely low extinction ratio. However, in optical systems, especially in fiber optic sensing applications, extremely high polarization degree and extremely low polarization degree indicators are expected to be obtained, which also puts extremely high requirements on the detection and measurement equipment. Currently, the equipment on the market generally claims to have an extinction ratio detection capability of 50dB, but in reality it is difficult to reach 50dB and maintain stability, which brings great uncertainty to the measurement; secondly, for the depolarizers in fiber optic sensing applications, the polarization degree can theoretically reach less than 0.1dB, but a common problem is that it is impossible to find equipment that can calibrate low polarization degrees.

[0003] The prior art 1 with the authorization announcement number CN 104280212, entitled A method for realizing accurate adjustment of the extinction ratio value, provides a method for realizing accurate adjustment of the extinction ratio value, and realizes the control of two orthogonal polarized lights by using the polarization beam splitting / combining principle, and achieves the purpose of adjusting the extinction ratio value by adjusting the power of the two polarized lights. The prior art 1 still has the following disadvantages:

[0004] ① The prior art 1 uses the same light source to split the light and then combines the two polarization states. Therefore, the problem is that the light source cannot be a coherent light source, that is, the spectrum width of the working light source cannot be narrow when measuring. When this optical path uses a narrow-band light source, interference will occur, resulting in unstable power and inability to measure normally. This is not applicable to applications that actually work in a narrow-band range in communications;

[0005] ② The closed loop of prior art 1 cannot independently switch on or off light of a certain polarization state, which limits the maximum extinction ratio that can be achieved;

[0006] ③ Although the starting point of the existing technology 1 is still to achieve different extinction ratios by changing the power of two orthogonal polarized light beams, it requires accurate measurement of the attenuator and optical path insertion loss in advance, and needs to maintain high repeatability during the calibration process, which is difficult to implement. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides an extinction ratio tester calibration device which can realize continuous adjustment of polarization degree over a wide range, is simple to operate, has a high repeatability, and can accurately measure the extinction ratio of both low and high polarization degrees. The device solves the problems in the background technology that the prior art has a narrow application range, cannot use narrow-spectrum light sources, has a small adjustable range of polarization degree, and has complex measurement and poor repeatability, resulting in large uncertainty.

[0008] To solve the above technical problems, the present invention is implemented as follows: a calibration device for an extinction ratio tester with an adjustable extinction ratio over a wide range, comprising: a first light source with adjustable power, a second light source with adjustable power, a first polarizer, a second polarizer and a beam combining device, wherein the first polarizer is arranged on the optical path of the light emitted by the first light source, and the second polarizer is arranged on the optical path of the light emitted by the second light source. The light emitted by the first light source passes through the first polarizer and is combined with the light emitted by the second light source passing through the second polarizer in the beam combining device into a beam of light containing a pair of orthogonal polarized lights.

[0009] Preferably, a first analyzer is arranged between the first polarizer and the beam combining device, and a second analyzer is arranged between the second polarizer and the beam combining device.

[0010] Another object of the present invention is to provide a calibration method for an extinction ratio tester with an adjustable extinction ratio over a wide range, which comprises the following steps:

[0011] Step 1: Turn on the first light source and the second light source for preheating respectively, and adjust the power of the first light source and the second light source respectively;

[0012] Step 2: Turn off the first light source and measure the power P1 at the output end of the beam combining device;

[0013] Step 3: Turn on the first light source, turn off the second light source, and measure the power P2 at the output end of the beam combining device;

[0014] Step 4: Calculate the extinction ratio according to the formula: PER = 10lg P1 / P2;

[0015] Step 5: Adjust the power of the first light source and the second light source to different values, and repeat the above steps 1 to 4 to obtain different extinction ratios.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] ① The present invention uses different independent lasers to work separately. First of all, the two lasers are naturally incoherent, so a narrow spectrum laser can be used. For the extinction ratio tester in special application fields, more accurate calibration can be performed. If a wavelength tunable light source is used, the extinction ratio values ​​corresponding to different wavelengths can be scanned and tested.

[0018] ② The working states of the two light sources can be controlled separately. Two polarizers are set in the optical path to achieve a polarization degree in the range of 0-60dB;

[0019] ③ Since the two light sources can be controlled separately, the component of a certain polarization state can be turned on at will, and an ordinary optical power meter can be used to perform accurate power measurement to determine the polarization state of the output light.

[0020] ④ The present invention only needs to measure the power at the output end of the beam combining device without considering other factors, and has high measurement repeatability and accurate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without any creative labor.

[0022] Figure 1 It is a structural schematic diagram of the calibration device of the extinction ratio tester with a wide adjustable extinction ratio as described in Implementation Option 1 of the present invention.

[0023] Figure 2 It is a structural schematic diagram of the calibration device of the extinction ratio tester with a wide adjustable extinction ratio as described in Implementation Option 2 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods and drawings. Here, the exemplary implementation methods of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0025] Example 1

[0026] Reference Figure 1, the preferred embodiment 1 of the present invention provides an extinction ratio tester calibration device with an adjustable extinction ratio in a wide range, which includes a first light source with adjustable power, a second light source with adjustable power, a first polarizer, a second polarizer, a first analyzer, a second analyzer and a beam combining device; the light emitted by the first light source is preset to propagate along the slow axis of the polarization-maintaining optical fiber, and is input into one input end of the beam combining device after passing through the first polarizer and the first analyzer in sequence, and the transmission axis direction of the first polarizer and the first analyzer is consistent with the slow axis direction of the polarization-maintaining optical fiber; the light emitted by the second light source is preset to propagate along the slow axis of the polarization-maintaining optical fiber, and is input into the other input end of the beam combining device after passing through the second polarizer and the second analyzer in sequence, and the transmission axis direction of the first polarizer and the first analyzer is consistent with the slow axis direction of the polarization-maintaining optical fiber, and the light emitted by the first light source and the light emitted by the second light source are combined by the beam combining device to obtain a pair of orthogonal polarized lights. The optical fibers used in this embodiment are all polarization-maintaining optical fibers.

[0027] The first light source includes a first light source body, a first isolator, a first splitter and a first driving circuit; the first light source body is electrically connected to the first driving circuit; the optical signal emitted by the first light source body passes through the first isolator to the first splitter, and the first splitter divides the optical signal into two paths, one of which is transmitted to the first polarizer, and the other is converted into an electrical signal through the first photoelectric conversion module, enters the first power closed-loop control circuit, and reaches the first driving circuit; the second light source includes a second light source body, a second isolator, a second splitter and a second driving circuit; the first light source body and the second driving circuit are electrically connected; the optical signal emitted by the second light source body passes through the second isolator to the second splitter, and the second splitter divides the optical signal into two paths, one of which is transmitted to the second polarizer, and the other is converted into an electrical signal through the second photoelectric conversion module, enters the second power closed-loop control circuit, and reaches the second driving circuit. The functions of the first power closed-loop control circuit and the second power closed-loop control circuit are to stabilize the power of the first light source and the second light source, respectively, and the existing power closed-loop control circuit can be used.

[0028] The first light source body is electrically connected to a first control circuit for adjusting power, and the first control circuit is electrically connected to a first drive circuit, thereby controlling the first light source body; the second light source body is electrically connected to a second control circuit for adjusting power, and the second control circuit is electrically connected to a second drive circuit, thereby controlling the second light source body. The first control circuit and the second control circuit are switches for the first light source and the second light source, and the first drive circuit and the second drive circuit are intermediate circuits for amplifying signals. The first control circuit, the second control circuit, the first drive circuit, and the second drive circuit can all use existing technologies.

[0029] The first light source body is electrically connected to a first temperature control circuit, and the second light source body is electrically connected to a second temperature control circuit. The first temperature control circuit and the second temperature control circuit are used to control the temperature, and existing technologies may be used.

[0030] The method for realizing a wide range of continuous adjustment of the polarization degree of a light source using the device comprises the following steps:

[0031] Step 1: Take a first light source, turn on the first light source through a first control circuit, and adjust its power.

[0032] Step 2: Take the second light source, turn on the second light source through the second control circuit, and adjust its power.

[0033] Step 3: Turn off the first light source and measure the power P1 at the output end of the beam combining device.

[0034] Step 4: Turn on the first light source and turn off the second light source, and measure the power P2 at the output end of the beam combining device.

[0035] Step 5: Calculate the extinction ratio according to the formula: extinction ratio PER = 10lg P1 / P2.

[0036] Step 6: Adjust the power of the first light source and the second light source to different values, and repeat the above steps 1 to 5 to obtain output lights with different polarization degrees.

[0037] Example 2

[0038] Reference Figure 2 , the preferred embodiment 2 of the present invention provides an extinction ratio tester calibration device with an adjustable extinction ratio in a wide range, which includes a first light source with adjustable power, a second light source with adjustable power, a first polarizer, a second polarizer and a beam combining device;

[0039] The beam combining device uses the 2×2 polarization-maintaining fiber beam splitter polarizer described in the Chinese invention patent with the authorization announcement number CN106932860A and the invention name 2×2 polarization-maintaining fiber beam splitter polarizer. The 2×2 polarization-maintaining fiber beam splitter polarizer has a polarization analyzer function. Therefore, the first polarization analyzer and the second polarization analyzer are reduced in Example 2 relative to Example 1.

[0040] The first light source is preset to emit light that propagates along the slow axis of the polarization-maintaining fiber. The light emitted by the first light source passes through the first polarizer and is then input into the beam combining device. The second light source is preset to emit light that propagates along the fast axis of the polarization-maintaining fiber. The light emitted by the second light source passes through the second polarizer and is then input into the beam combining device. Finally, the two are combined in the beam combining device into a light beam containing a pair of orthogonal polarized lights. The transmission axis direction of the first polarizer is consistent with the slow axis direction of the polarization-maintaining fiber; the transmission axis direction of the second polarizer is consistent with the fast axis direction of the polarization-maintaining fiber. The optical fibers used in this embodiment are all polarization-maintaining fibers.

[0041] The first light source includes a first light source body, a first isolator, a first splitter and a first driving circuit; the first light source body is electrically connected to the first driving circuit; the optical signal emitted by the first light source body passes through the first isolator to the first splitter, and the first splitter divides the optical signal into two paths, one of which is transmitted to the first polarizer, and the other is converted into an electrical signal through the first photoelectric conversion module, enters the first power closed-loop control circuit, and reaches the first driving circuit; the second light source includes a second light source body, a second isolator, a second splitter and a second driving circuit; the first light source body and the second driving circuit are electrically connected; the optical signal emitted by the second light source body passes through the second isolator to the second splitter, and the second splitter divides the optical signal into two paths, one of which is transmitted to the second polarizer, and the other is converted into an electrical signal through the second photoelectric conversion module, enters the second power closed-loop control circuit, and reaches the second driving circuit. The functions of the first power closed-loop control circuit and the second power closed-loop control circuit are to stabilize the power of the first light source and the second light source, respectively, and the existing power closed-loop control circuit can be used. The first drive circuit and the second drive circuit are intermediate circuits for amplifying signals. The first power closed-loop control circuit, the second power closed-loop control circuit, the first drive circuit, and the second drive circuit can all use existing technologies.

[0042] The first light source also includes a first optical switch and a first adjustable attenuator. The optical signal propagates from the first splitter, passes through the first optical switch and the first adjustable attenuator, and then reaches the first polarizer. The second light source also includes a second optical switch and a second adjustable attenuator. The optical signal propagates from the second splitter, passes through the second optical switch and the second adjustable attenuator, and then reaches the second polarizer.

[0043] The first light source body is electrically connected to a first temperature control circuit, and the second light source body is electrically connected to a second temperature control circuit. The first temperature control circuit and the second temperature control circuit are used to control the temperature, and existing technologies may be used.

[0044] The method for realizing a wide range of continuous adjustment of the polarization degree of a light source using the device comprises the following steps:

[0045] Step 1: Take a first light source, turn on the first light source through a first optical switch, and adjust its power through a first adjustable attenuator.

[0046] Step 2: Take a second light source, turn on the second light source through a second optical switch, and adjust its power through a second adjustable attenuator.

[0047] Step 3: Turn off the first light source and measure the power P1 at the output end of the beam combining device.

[0048] Step 4: Turn on the first light source and turn off the second light source, and measure the power P2 at the output end of the beam combining device.

[0049] Step 5: Calculate the extinction ratio according to the formula: extinction ratio PER = 10lg P1 / P2.

[0050] Step 6: Adjust the power of the first light source and the second light source to different values, and repeat the above steps 1 to 5 to obtain output lights with different polarization degrees.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A calibration device for an extinction ratio tester with a wide range of adjustable extinction ratio, characterized in that: It comprises a first light source with adjustable power, a second light source with adjustable power, a first polarizer, a second polarizer and a beam combining device, wherein the first polarizer is arranged on the optical path of the light emitted by the first light source, and the second polarizer is arranged on the optical path of the light emitted by the second light source, and the light emitted by the first light source passes through the first polarizer and is combined with the light emitted by the second light source passing through the second polarizer in the beam combining device to form a beam of light containing a pair of orthogonal polarized lights; the first light source comprises a first light source body, a first isolator, a first splitter and a first driving circuit; the first light source body is electrically connected to the first driving circuit; the optical signal emitted by the first light source body passes through the first isolator to the first splitter, and the first splitter divides the optical signal into two paths, one path The first path is transmitted to the first polarizer, and the other path is converted into an electrical signal through the first photoelectric conversion module, enters the first power closed-loop control circuit, and reaches the first drive circuit; the second light source includes a second light source body, a second isolator, a second splitter and a second drive circuit; the first light source body is electrically connected to the second drive circuit; the optical signal emitted by the second light source body passes through the second isolator and reaches the second splitter, and the second splitter divides the optical signal into two paths, one path is transmitted to the second polarizer, and the other path is converted into an electrical signal through the second photoelectric conversion module, enters the second power closed-loop control circuit, and reaches the second drive circuit; the first light source body is electrically connected to the first temperature control circuit, and the second light source body is electrically connected to the second temperature control circuit.

2. The extinction ratio tester calibration device with a wide range of adjustable extinction ratio as claimed in claim 1, characterized in that: A first analyzer is arranged between the first polarizer and the beam combining device; and a second analyzer is arranged between the second polarizer and the beam combining device.

3. The extinction ratio tester calibration device with a wide range of adjustable extinction ratio as claimed in claim 1 or 2, characterized in that: The first light source body is electrically connected to a first control circuit for adjusting power, the first control circuit is electrically connected to the driving circuit, and thus controls the first light source body; the second light source body is electrically connected to a second control circuit for adjusting power, the second control circuit is electrically connected to the driving circuit, and thus controls the second light source body.

4. The extinction ratio tester calibration device with a wide range of adjustable extinction ratio as claimed in claim 1 or 2, characterized in that: The first light source also includes a first optical switch and a first adjustable attenuator. The optical signal propagates from the first splitter, passes through the first optical switch and the first adjustable attenuator, and then reaches the first polarizer. The second light source also includes a second optical switch and a second adjustable attenuator. The optical signal propagates from the second splitter, passes through the second optical switch and the second adjustable attenuator, and then reaches the second polarizer.

5. A calibration method using the extinction ratio tester calibration device with a wide range of adjustable extinction ratio according to any one of claims 1 to 4, characterized in that: It includes the following steps: Step 1: Turn on the first light source and the second light source for preheating respectively, and adjust the power of the first light source and the second light source respectively; Step 2: Turn off the first light source and measure the power P1 at the output end of the beam combining device; Step 3: Turn on the first light source, turn off the second light source, and measure the power P2 at the output end of the beam combining device; Step 4: Calculate the extinction ratio according to the formula: PER = 10lg P1 / P2; Step 5: Adjust the power of the first light source and the second light source to different values, and repeat the above steps 1 to 4 to obtain different extinction ratios.

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