CN211425818U - Polarizer straight waveguide tail fiber polarization crosstalk test system - Google Patents

Abstract

The utility model discloses a polarizer straight waveguide pigtail polarization crosstalk test system, comprising: a light source, a splitter, a polarizer and a collection device, wherein the light source is connected to an input end of the splitter through a polarization maintaining fiber , the splitter is provided with a monitoring port and one or more test ports, the monitoring port is connected with the monitoring input end of the acquisition device through the polarization maintaining fiber, and each test port is connected with the polarizer through the polarization maintaining fiber. An optical path input end is connected, each optical path output end of the polarizer is connected to an input end of a device under test through a polarization maintaining fiber, and the output end of each device under test is respectively connected with the test input of the acquisition device end connection. The utility model adopts the lithium niobate array straight waveguide with single polarization operation as the polarizer, which breaks through the problems of low test accuracy, low efficiency and high cost, and also adopts a multi-channel collector, which can realize multi-channel pigtail polarization crosstalk and high cost. Insertion loss simultaneous acquisition requirements.

Description

A polarizer straight waveguide pigtail polarization crosstalk test system

technical field

The utility model relates to the technical field of optical fibers, in particular to a polarizer straight waveguide pigtail polarization crosstalk test system.

Background technique

In the fiber optic current transformer, the photoelectric properties of its key device, the lithium niobate direct waveguide phase modulator, have a great influence on the performance of the entire sensor. Titanium-diffused lithium niobate linear waveguide phase modulator has dual polarization characteristics, which can simultaneously transmit transverse electric (TE) and transverse magnetic (TM) modes, and can simultaneously modulate the phases of these two modes , this feature makes it popular in the field of optical fiber sensing, especially in the development of fiber optic current sensors. As shown in Figure 1, a Super-luminescent Diode (SLD) light source 1', a light receiving component 2', a preamplifier 3', an A/D converter 4', a signal processor 5', a D/A Converter 6', circulator 7', polarizer 8', straight waveguide phase modulator 9', PM fiber delay 10', λ/4 wave plate 11', fiber coil 12', mirror 13' , and the cut-off wire 14' to form a fiber optic current transformer system. In this system, using the straight waveguide phase modulator 8' to form the optical path of the fiber optic current sensor has smaller temperature error and vibration error, and better time reciprocity.

With the application of current transformers, the temperature drift of measurement accuracy is still the technical bottleneck restricting high-performance current transformers, and the titanium diffused lithium niobate straight waveguide is one of the key components of the system, as shown in Figure 2 for the straight waveguide Schematic diagram of the structure, including a titanium diffused lithium niobate substrate 21', a waveguide 22', and an electrode 23'. It is found that the variation of pigtail polarization crosstalk is the main cause of system polarization error under full temperature conditions. In addition, the system temperature noise is also an important factor affecting the high performance of the current transformer. The study found that the change of the insertion loss of the straight waveguide has a direct relationship with the noise fluctuation. Therefore, the polarization crosstalk and the change of the insertion loss of the pigtail at full temperature are important for evaluating the system polarization error and temperature noise. are two very important indicators.

The existing testing methods have the following defects:

Since the titanium diffused straight waveguide is a dual-polarization working mode, the light input to the waveguide needs to be polarized before the pigtail polarization crosstalk of TE/TM can be tested respectively. About -20dB, while the pigtail polarization crosstalk of the straight waveguide is better than -27dB, and even reaches -34dB. Obviously, the optical fiber polarizer cannot meet the test accuracy requirements. In addition, polarization control components are used for polarizing. Although the accuracy can meet the requirements, due to the spatial optical path and poor stability, the polarizer direction needs to be calibrated frequently, the operation is cumbersome, and the change of the polarization crosstalk of the pigtail cannot be monitored from time to time. The test efficiency is low, which is not conducive to realizing the requirements of batch high-efficiency testing.

Utility model content

Based on this, it is necessary to provide a method to solve the technical problems that the existing waveguide testing methods have poor stability, cumbersome operations, large loss of polarization control components, high cost, and low testing efficiency, which are not conducive to realizing the requirements of batch high-efficiency testing. Polarizer straight waveguide pigtail polarization crosstalk test system.

The utility model provides a polarizer straight waveguide pigtail polarization crosstalk test system, comprising: a light source, a splitter, a polarizer and a collection device, wherein the light source is connected to an input end of the splitter through a polarization maintaining fiber , the splitter is provided with a monitoring port and one or more test ports, the monitoring port is connected with the monitoring input end of the acquisition device through the polarization maintaining fiber, and each test port is connected with the polarizer through the polarization maintaining fiber. An optical path input end is connected, each optical path output end of the polarizer is connected to an input end of a device under test through a polarization maintaining fiber, and the output end of each device under test is respectively connected with the test input of the acquisition device end connection.

Further, the polarizer is an arrayed waveguide chip.

Further, the polarizer includes: X-cut y-transmitting lithium niobate material chip substrate, one or more groups of polarizer straight waveguides are arranged on the chip substrate, and each group of polarizer straight waveguides is cut between the straight waveguides. An isolation slot, the input end of each group of the polarizer straight waveguides is the optical path input end, and the output end of each group of the polarizer straight waveguides is the optical path output end.

Still further, the isolation groove is coated with a light-absorbing substance.

Still further, the input end and the output end of the polarizer straight waveguide are coupled by polarization-maintaining fibers, and the polarizer straight waveguide is an annealed proton exchange polarizer straight waveguide.

Further, it also includes a temperature change box for accommodating the device under test, and each optical path output end of the polarizer is inserted into the temperature change box through a polarization maintaining fiber to be connected to an input end of a device under test. The output ends of the device to be tested are respectively protruded from the temperature change box and connected to the test input end of the acquisition device.

Further, it also includes a temperature sensor for measuring the temperature in the temperature change box, and the output end of the temperature sensor is connected in communication with the temperature input end of the collecting device.

Further, the collection device is further provided with a power monitoring port for monitoring the optical power of the test input terminal and the monitoring input terminal.

Further, a flange plate is also included, and each of the test ports of the splitter is connected to an optical path input end of the polarizer through the flange plate through a polarization-maintaining optical fiber.

Further, each output end of the optical path of the polarizer and the input end of a device to be tested are welded to the axis by polarization maintaining, and the welding angle is 0° or 90°.

The utility model adopts the lithium niobate array straight waveguide with single polarization operation as the polarizer, which breaks through the problems of low test accuracy, low efficiency and high cost, and also adopts a multi-channel collector, which can realize multi-channel pigtail polarization crosstalk and high cost. Insertion loss simultaneous acquisition requirements.

Description of drawings

Fig. 1 is the system block diagram of the fiber optic current transformer;

Figure 2 is a schematic diagram of a straight waveguide structure;

3 is a system schematic diagram of a polarizer straight waveguide pigtail polarization crosstalk test system of the present invention;

FIG. 4 is a schematic diagram of the structure of the polarizer.

Detailed ways

The present utility model will be described in further detail below with reference to the accompanying drawings and specific embodiments.

3 is a system schematic diagram of a polarizer straight waveguide pigtail polarization crosstalk test system of the present invention, including: a light source 1, a splitter 2, a polarizer 3, and a collection device 4. The The light source 1 is connected to the input end of the splitter 2 through the polarization maintaining fiber, the splitter 2 is provided with a monitoring port and one or more test ports, and the monitoring port is connected to the monitoring input end of the acquisition device 4 through the polarization maintaining fiber connection, each of the test ports is connected to an optical path input end of the polarizer 3 through a polarization maintaining fiber, and each optical path output end of the polarizer 3 is connected to an input end of a device under test through a polarization maintaining fiber, The output end of each device under test is respectively connected with the test input end of the acquisition device.

Specifically, the depolarized light emitted by the light source 1 is divided into multiple channels by a splitter, wherein, preferably, it is divided into 16 channels in total, 01-15 channels are used as the test input light, and 16 channels are used for monitoring the stability of the light source and calculating the reference. , the light output from the splitter 2 from the 01-15 channel enters the polarizer 3, and the depolarized light enters the polarizer 3 and becomes a single-polarized linearly polarized light, which is output through the polarization-maintaining fiber of the polarizer 3, preferably a polarization-maintaining pigtail fiber Output, connect with DUT 801-815. The period to be measured 801-815 is preferably a straight waveguide to be measured, more preferably a titanium diffused straight waveguide. The straight waveguide output pigtail to be tested is connected to the automatic acquisition system through an adapter, and the polarization crosstalk and insertion loss variation of the pigtail are collected in real time.

The utility model adopts the lithium niobate array straight waveguide with single polarization operation as the polarizer, which breaks through the problems of low test accuracy, low efficiency and high cost, and also adopts a multi-channel collector, which can realize multi-channel pigtail polarization crosstalk and high cost. Insertion loss simultaneous acquisition requirements.

In one embodiment, the polarizer 3 is an arrayed waveguide chip.

As shown in FIG. 4 , in one embodiment, the polarizer 3 includes: a chip substrate 31 made of lithium niobate material, and one or more groups of polarizers are arranged on the chip substrate 31 . Waveguide 32, an isolation groove 33 is cut between each group of polarizer straight waveguides 32, the input end of each group of polarizer straight waveguides 32 is the input end of the optical path, and the polarizer straight waveguides 32 of each group are The output end is the output end of the optical path.

In this embodiment, the polarizer 3 is used to adjust the depolarized light of the light source 1 to single-polarized linearly polarized light.

In one embodiment, the isolation groove 33 is coated with a light-absorbing substance.

In this embodiment, the crosstalk between the waveguides is prevented by coating the light absorbing material.

In one embodiment, the input end and the output end of the polarizer straight waveguide 32 are coupled with polarization maintaining fibers, and the polarizer straight waveguide 32 is an annealed proton exchange polarizer straight waveguide.

The chip of this embodiment adopts annealed proton exchange straight waveguide, only supports TE mode transmission, the input and output are coupled by polarization-maintaining fiber, and finally can be packaged into a polarizer module with a tube shell. It is much higher than the crosstalk value of the test straight waveguide and meets the test requirements. The single loss is only about 1.2dB, which is convenient for batch testing.

In one embodiment, it also includes a temperature change box 5 for accommodating the device under test, and each optical path output end of the polarizer 3 is inserted into the temperature change box 5 and a device under test through a polarization maintaining fiber The input end of each device to be tested is connected to the input end of the device under test, and the output end of each device to be tested passes through the temperature change box 5 and is connected to the test input end of the acquisition device.

In this embodiment, a temperature change box is added, and the temperature change box has a high and low temperature cycle function, which can realize constant speed temperature change.

In one of the embodiments, a temperature sensor 6 for measuring the temperature in the temperature change box 5 is also included, and the output end of the temperature sensor 6 is connected in communication with the temperature input end of the collecting device 4 .

In this embodiment, a temperature sensor is used to record the temperature change of the temperature change box in real time.

In one embodiment, the collection device 4 is further provided with a power monitoring port 41 for monitoring the optical power of the test input terminal and the monitoring input terminal.

In this embodiment, the optical power output by the demultiplexer is monitored through the power monitoring port for reference.

In one embodiment, a flange 7 is also included, and each of the test ports of the splitter 2 is connected to an optical path input end of the polarizer 3 through the flange 7 through a polarization-maintaining optical fiber.

In this embodiment, a flange is provided, and the light output from the test port of the splitter enters the polarizer through the connection point of the flange.

In one embodiment, each output end of the optical path of the polarizer 3 and the input end of a device under test are welded to the axis by polarization maintaining, and the welding angle is 0° or 90°.

After the light output from the test port of the splitter in this embodiment enters the polarizer, it is output through the polarization-maintaining pigtail fiber of the polarizer, and is fused with the device under test. The polarizer and the straight waveguide pigtail are both fast-axis and fixed-axis. , so when the welding angle is selected as 0° (90°), the TE(TM) mode is transmitted in the straight waveguide.

As the best embodiment of the present utility model, a polarizer straight waveguide pigtail polarization crosstalk test system, as shown in Figure 3, includes: a light source 1, a splitter 2, a polarizer 3, a collection device 4, a capacitor The temperature change box 5, the temperature sensor 6, and the flange 7 of the device to be tested are placed. The light source 1 is connected to the input end of the splitter 2 through a polarization-maintaining optical fiber. The splitter 2 is provided with a monitoring port, a or a plurality of test ports, the monitoring ports are connected with the monitoring input end of the acquisition device 4 through the polarization maintaining fiber, and each test port is input through the polarization maintaining fiber through an optical path between the flange 7 and the polarizer 3 Each optical path output end of the polarizer 3 is inserted into the temperature change box 5 through a polarization maintaining fiber and connected to the input end of a device under test, and each optical path output end of the polarizer 3 is connected to a The input end of the device to be tested is welded to the axis by polarization-maintaining welding, and the welding angle is 0° or 90°, and the output end of each device to be tested passes through the temperature change box 5 and the test input of the acquisition device respectively. The output end of the temperature sensor 6 is connected in communication with the temperature input end of the collection device 4, and the collection device 4 is also provided with a power monitoring port for monitoring the optical power of the test input end and the monitoring input end. 41;

The polarizer 3 is an arrayed waveguide chip, and the polarizer 3 includes: a chip substrate 31 of X-cut y-transmitting lithium niobate material, and one or more groups of polarizer straight waveguides 32 are arranged on the chip substrate 31 , an isolation groove 33 is cut between each group of polarizer straight waveguides 32, the isolation groove 33 is coated with a light-absorbing material, the input end of each group of polarizer straight waveguides 32 is the input end of the optical path, and each group The output end of the polarizer straight waveguide 32 is the output end of the optical path, the input end and the output end of the polarizer straight waveguide 32 are coupled by a polarization maintaining fiber 34, and the polarizer straight waveguide 32 is an annealed proton The polarizer straight waveguide is exchanged, and the outer casing 35 is encapsulated.

The principle of the optical path is: the depolarized light emitted by the light source is divided into 16 channels by the splitter, the 01-15 channels are used as the test input light, the 16 channels are used for monitoring the stability of the light source and the calculation reference, and the light output by the 1-15 channels is passed through the splitter. The flange connection point enters the polarizer, and the depolarized light enters the polarizer and becomes single-polarized linearly polarized light, which is output through the polarization-maintaining pigtail of the polarizer, and is fused with the device under test. The polarizer and the straight waveguide tail The fibers are all fast-axis and fixed-axis, so when the splice angle is selected as 0° (90°), the transmission in the straight waveguide is TE(TM) mode, and the straight waveguide output pigtail is connected to the automatic acquisition system through the adapter to collect TE in real time Pigtail polarization crosstalk and insertion loss variation in (TM) mode.

Introduction of components:

Light source 1: SLD high-power depolarized light source, power 10±1mW.

Splitter 2: 1×16 fiber type beam splitter to realize light splitting.

Polarizer 3: Arrayed waveguide chip, as shown in Figure 4, 17 straight waveguides are designed on the X-cut y-transmitting lithium niobate material, 15 sets are used for testing, 2 sets are used as spares, and an isolation is cut between each set of waveguides The grooves are coated with light-absorbing substances to isolate them to prevent crosstalk between the waveguides. The chip adopts annealed proton exchange straight waveguide, only supports TE mode transmission, input and output are coupled with polarization-maintaining fiber, and finally packaged into a polarizer module with a tube shell.

Since the polarizer is made of annealed proton exchange waveguide, the waveguide made by this process has the function of polarization (single polarization working state), so the pigtail polarization crosstalk is high. Among them, the insertion loss of a single straight waveguide is 1.2dB, including the coupling loss of 0.3dB/end, the transmission loss of 0.3dB/cm, and the total length of 2cm, so the total loss is 0.3dB×2 ends+0.3dB×2cm=1.2dB. Since the polarization crosstalk of the pigtail fiber of this module can be as high as 38dB, which is much higher than the crosstalk value of the test straight waveguide and meets the test requirements, the single loss is only about 1.2dB, which is convenient for batch testing.

Device under test: titanium diffused straight waveguide, which can transmit two modes of TE/TM simultaneously.

Temperature change box 5: It has the function of high and low temperature cycle, which can realize constant speed change of temperature.

Temperature sensor 6: used to record the temperature change of the temperature change box in real time.

Power monitoring port 41: Monitor the optical power output by the 16-channel splitter for reference.

Automatic acquisition system 4: implement acquisition of pigtail polarization crosstalk and insertion loss variation of the device under test.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as limiting the scope of the present invention. It should be pointed out that for those of ordinary skill in the art, some modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for this utility model shall be subject to the appended claims.

Claims (10)

1. A polarizer straight waveguide pigtail polarization crosstalk test system, characterized in that, comprising: a light source (1), a splitter (2), a polarizer (3), and a collection device (4), the The light source (1) is connected to the input end of the splitter (2) through a polarization-maintaining optical fiber, and the splitter (2) is provided with a monitoring port and one or more test ports, and the monitoring port is connected to the splitter (2) through the polarization-maintaining optical fiber. The monitoring input end of the collection device (4) is connected, each of the test ports is connected to an optical path input end of the polarizer (3) through a polarization maintaining fiber, and each optical path output end of the polarizer (3) passes through The polarization-maintaining fiber is connected to an input end of a device to be tested, and the output end of each device to be tested is respectively connected to the test input end of the acquisition device. 2 . The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 1 , wherein the polarizer ( 3 ) is an arrayed waveguide chip. 3 . 3. The polarizer straight-waveguide pigtail polarization crosstalk test system according to claim 2, wherein the polarizer (3) comprises: a chip substrate (31) of X-cut y-transmitting lithium niobate material, One or more groups of polarizer straight waveguides (32) are arranged on the chip substrate (31), an isolation groove (33) is cut between each group of polarizer straight waveguides (32), and each group of polarizer straight waveguides (32) is The input end of the straight polarizer waveguide (32) is the input end of the optical path, and the output end of each group of the straight polarizer waveguides (32) is the output end of the optical path. 4 . The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 3 , wherein the isolation groove ( 33 ) is coated with a light absorbing material. 5 . 5. The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 3, wherein the input end and the output end of the polarizer straight waveguide (32) adopt polarization maintaining fiber coupling, and the The polarizer straight waveguide (32) is an annealed proton exchange polarizer straight waveguide. 6. The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 1, further comprising a temperature change box (5) for accommodating the device under test, the polarizer (3) ) of each optical path output end is inserted into the temperature change box (5) through a polarization-maintaining fiber to be connected to the input end of a device to be tested, and the output end of each device to be tested is respectively connected from the temperature change box (5) The outlet is connected to the test input end of the collection device. 7. The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 6, characterized in that, further comprising a temperature sensor (6) for measuring the temperature in the temperature change box (5), the temperature The output end of the sensor (6) is connected in communication with the temperature input end of the collecting device (4). 8. The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 1, wherein the acquisition device (4) is further provided with monitoring the test input end and the optical power of the monitoring input end power monitoring port (41). 9. The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 1, further comprising a flange (7), each of the test ports of the splitter (2) The polarization-maintaining optical fiber is connected to an optical path input end of the polarizer (3) through the flange plate (7). 10 . The polarizer straight waveguide pigtail polarization crosstalk test system according to claim 1 , wherein the output end of each optical path of the polarizer (3) is aligned with the input end of a device under test. 11 . Polarization maintaining welding, and the welding angle is 0° or 90°.

Images