Optical fiber automatic coupling device

Abstract

The utility model relates to an optical fiber automatic coupling device, which comprises a laser, and an optical fiber collimator, an adjustable optical wedge group, an optical fiber coupler and an optical power detection module which are sequentially arranged along the emitting direction of a laser beam, the optical power detection module is connected with the optical fiber coupler through a single-mode optical fiber and used for monitoring optical power coupled into the single-mode optical fiber and converting a monitored optical signal into an electric signal, and the optical power detection module is connected with the control processor; the control processor is used for controlling the first stepping motor and / or the second stepping motor to act based on the difference value between the actual value collected by the optical power detection module in real time and the threshold voltage value corresponding to the target optical power. The scheme has the advantages of good stability, high automation degree and miniaturization.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber coupling, in particular to an optical fiber automatic coupling device and method. Background Art

[0002] Fiber automatic coupling has important value in cutting-edge fields such as quantum precision measurement instruments and space cold atomic optical clocks. Fiber automatic coupling technology can achieve high-efficiency coupling and transmission of optical signals, thereby improving the stability and accuracy of the system. In addition, real-time fiber automatic coupling technology can replace the actual effects of technical means such as laser power locking and laser power compensation to a certain extent, and can also reduce the number and volume of devices in the optical system and reduce the complexity of the system, thereby improving the reliability and life of the system.

[0003] At present, optical fibers and coupling devices are expensive, and most of the cost of making related devices lies in the packaging process, accounting for about 70% to 90% of the total cost of the entire production process. In the production process of optical fiber coupling and docking, more than 80% of the optical fiber-to-optical coupling is completed by traditional labor-intensive manual or semi-automatic methods, which has outstanding problems such as low yield, low efficiency and high cost. With the development of automation of optical fiber alignment and coupling, various automation structures have emerged. At present, the equipment for automatic optical fiber coupling is usually improved by improving manual alignment and coupling to motor-driven alignment, driven by a stepper motor, or corrected by a feedback system through image processing, but the correction time interval is long, and real-time correction cannot be achieved, and the degree of automation and accuracy are not very high.

[0004] With the development of automation of fiber alignment and coupling, various automatic coupling structures have emerged. At present, the automatic fiber coupling equipment is usually improved by manual alignment and coupling to motor-driven alignment, driven by a stepper motor, or corrected by a feedback system through image processing. However, the correction time interval is long, and real-time correction cannot be achieved. In addition, the degree of automation and accuracy are not very high.

[0005] Therefore, if the optical fiber can be automatically coupled and corrected in real time, the coupling efficiency and accuracy will be greatly improved. In many fields with high requirements for optical fiber automatic coupling, such as: long-term continuous unattended observation of high-precision quantum gravimeters at seismic network stations; continuous mapping of dynamic absolute gravity on marine ships, etc., the use of optical fiber automatic coupling technology and equipment with real-time correction can greatly improve the long-term stability of the system, greatly improve the coupling efficiency and high-precision optical fiber coupling efficiency, and greatly improve work efficiency and the reliability of test data.

[0006] In the prior art, a Chinese utility model patent application with publication number CN 109738996 A discloses an automatic fiber optic coupling device, which controls a motor through a computer, and the motor drives the optical wedge to rotate, and adjusts the beam azimuth and spatial position of the optical wedge to achieve the best efficiency of fiber optic coupling. However, when factors such as temperature changes or environmental vibrations cause the optical path parts in the system to deform, the angle of the incident light will shift, which will cause the fiber optic coupling efficiency to decrease. Therefore, in actual work, the traditional automatic fiber optic coupling device will encounter a problem of not being able to monitor and fine-tune in real time to achieve the best coupling efficiency. In fact, it is only an electric fiber optic coupling device and method that replaces manual operation, and cannot achieve fully automatic coupling.

[0007] The Chinese utility model patent application with publication number CN 114488434 A discloses an automatic optical fiber coupling device and method. The scheme is an adjustment method that constitutes a feedback loop, which can realize automatic optical fiber coupling. However, this feedback is to calculate the spatial coordinate information of the optical fiber end face through the image recognition module and transmit it to the feedback control module. The feedback control module issues a control command to realize coupling. After the coupling is realized, the inspection time interval is set to one hour. After each inspection time interval, the feedback control module automatically runs to achieve the best coupling efficiency. The coupling accuracy and efficiency of this feedback system are not particularly high. The time and accuracy of image processing cannot be guaranteed. The set inspection time is a time interval, and real-time correction cannot be achieved. In addition, the manufacturing cost and R&D cost of the system are also high. Utility Model Content

[0008] In order to solve the above problems, the utility model provides an optical fiber automatic coupling device to achieve the purpose of automatic optical fiber coupling and real-time correction.

[0009] An optical fiber automatic coupling device comprises a laser and an optical fiber collimator, an adjustable optical wedge group, an optical fiber coupler and an optical power detection module which are sequentially arranged along the direction of the laser beam emission;

[0010] The adjustable optical wedge group includes a first wedge block and a second wedge block which are sequentially arranged along the incident direction to the emitting direction of the light beam, and the central areas of the first wedge block and the second wedge block are used for passing light; the first wedge block and the second wedge block are respectively driven to move by a first stepper motor and a second stepper motor, and the first stepper motor and the second stepper motor are controlled by a control processor through a motor driver;

[0011] The optical power detection module is connected to the optical fiber coupler through the single-mode optical fiber, and is used to monitor the optical power coupled into the single-mode optical fiber and convert the monitored optical signal into an electrical signal. The optical power detection module is connected to the control processor;

[0012] The control processor is used to control the action of the first stepper motor and / or the second stepper motor based on the difference between the actual value collected in real time by the optical power detection module and the threshold voltage value corresponding to the target optical power.

[0013] Preferably, the control processor includes an analog-to-digital conversion module, which performs analog-to-digital conversion processing on the electrical signal from the optical power detection module.

[0014] Preferably, a host computer is further included, which communicates with the control processor and is used to compare the difference between the actual value collected in real time by the optical power detection module and the threshold voltage value corresponding to the target optical power.

[0015] Preferably, the first stepper motor and the first wedge block, as well as the second stepper motor and the second wedge block are connected via worm gear transmission respectively.

[0016] Preferably, a first wedge block mounting hole is provided on the worm wheel fixed to the first wedge block, and the first wedge block is fixed in the first wedge block mounting hole by a pressure ring; a second wedge block mounting hole is provided on the worm wheel fixed to the second wedge block, and the second wedge block is fixed in the second wedge block mounting hole by a pressure ring.

[0017] Preferably, a photodiode amplifier circuit is provided at the receiving end of the optical fiber coupler, and the output end of the adjustable optical wedge group is connected to the input end of the optical fiber coupler through the photodiode amplifier circuit.

[0018] The utility model has the following beneficial effects due to the adoption of the above scheme:

[0019] Good stability: Use the controller to monitor the optical power in real time and adjust the optical fiber coupling to ensure the stability of the optical power, and control the voltage feedback to the motor drive to make the control result more accurate;

[0020] High degree of automation: Real-time monitoring of optical power is used to feed back to the control processor for control, thus achieving automatic control; BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an optical fiber automatic coupling device;

[0022] Figure 2 It is a schematic diagram of the installation structure of the stepping motor and the first wedge;

[0023] Figure 3 is a flow chart of an optical fiber automatic coupling method;

[0024] Reference numerals:

[0025] Laser 1, fiber collimator 2, adjustable wedge group 3, first wedge block 31, second wedge block 32, first stepper motor 33, second stepper motor 34, gear group 35, worm gear 36, worm 37, fiber coupler 4, optical power detection module 5, control processor 6, motor driver 7, host computer 8. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below.

[0027] Embodiment 1:

[0028] This embodiment 1 provides an optical fiber automatic coupling device, comprising a laser 1 and an optical fiber collimator 2, an adjustable wedge group 3, an optical fiber coupler 4 and an optical power detection module 5 which are sequentially arranged along the emission direction of the laser beam.

[0029] The light beam emitted by the laser 1 passes through the optical fiber collimator 2 , so that the incident light entering the adjustable wedge group 3 becomes a nearly parallel light beam with a very small divergence angle, and the nearly parallel light beam enters the adjustable wedge group 3 .

[0030] The adjustable optical wedge group 3 includes a first wedge 31 and a second wedge 32 arranged in sequence from the incident direction to the emitting direction of the light beam. The first wedge 31 and the second wedge 32 are optical wedges. The central areas of the first wedge 31 and the second wedge 32 are used for passing light. By adjusting the relative positions of the first wedge 31 and the second wedge 32, the angle of the light beam passing through the first wedge 31 and the second wedge 32 can be deflected. The first wedge 31 and the second wedge 32 are driven to move by a first stepper motor 33 and a second stepper motor 34, respectively. The first stepper motor 33 and the second stepper motor 34 are driven by the control processor 6 through the motor driver 7.

[0031] The light beam emitted from the adjustable wedge group 3 enters the fiber coupler 4, which includes a coupler equipped with a focusing lens and a fixed base, and can focus a nearly parallel light beam with a very small divergence angle onto the end face of the fiber core and couple it into the fiber.

[0032] The optical power detection module 5 is connected to the optical fiber coupler 4 via a single-mode optical fiber, and is used to monitor the optical power coupled into the single-mode optical fiber and convert the monitored optical signal into an electrical signal.

[0033] The optical power detection module 5 is connected to the control processor 6, which receives the electrical signal from the optical power detection module 5 and transmits it to the host computer 8; the control processor 6 includes an ADC module, which performs analog-to-digital conversion on the electrical signal from the optical power detection module 5 and converts it into data that can be recognized and processed by the host computer 8.

[0034] The host computer 8 compares the difference between the actual value collected in real time by the optical power detection module 5 and the threshold voltage value corresponding to the target optical power. If the difference exceeds the preset value, the control processor 6 controls the first wedge 31 and / or the second wedge 32 to move until the difference between the actual value collected in real time by the optical power detection module 5 and the threshold voltage value meets the preset value. In an ideal state, the preset value is 0, which means that the actual value collected by the optical power detection module 5 is the same as the threshold voltage value. In practical applications, the preset value can also be other values ​​within the allowable error range obtained from prior experiments.

[0035] The above-mentioned automatic optical fiber coupling device uses a laser power monitoring module to monitor the laser power at the output end of the optical fiber in real time, and feeds back the monitoring signal to the control processor 6. When the monitoring signal changes, it means that the incident light angle is offset. The output signal of the motor driver 7 of the stepper motor is fed back and controlled in real time through the fine-tuning algorithm to change the motor rotation angle and speed. The motor movement is converted into the rotation of the optical wedge through the transmission device, thereby changing the laser azimuth and spatial position of the incident optical fiber in real time to keep it in the optimal state, thereby achieving long-term stability of the optical power after the optical fiber. In this device, the laser power detection signal coupled into the single-mode optical fiber is collected in real time according to the laser power monitoring module as the evaluation index of the system. The control processor 6 forms a set of control quantities through the evaluation index, and the control quantity is fed back to the motor driver 7 to control the stepper motor to drive the first wedge 31 and / or the second wedge 32 to rotate and fine-tune. By iterating the difference between the real-time collection value and the threshold voltage value, the optimal coupling efficiency is finally achieved. Normally, the laser coupled into the single-mode optical fiber is continuously controllable, so the signal collected by the optical power detection module 5 is also continuously controllable. Therefore, the control processor 6 can generate control quantities in real time and continuously to control the stepper motor in real time and realize real-time feedback.

[0036] The first wedge block 31 and the second wedge block 32 are controlled by independent stepper motors, respectively. The first stepper motor 33 and the first wedge block 31, and the second stepper motor 34 and the second wedge block 32 are respectively connected through a worm gear 36 and a worm gear 37. The connection structure between the first stepper motor 33 and the first wedge block 31 is the same as the connection structure between the second stepper motor 34 and the second wedge block 32. Here, the connection structure between the first stepper motor 33 and the first wedge block 31 is described. Figure 2As shown, the first wedge 31 is fixed to the worm wheel 36, and the rotation of the worm wheel 36 drives the first wedge 31 to rotate synchronously. The worm wheel 36 is meshed with the worm 37, and the worm 37 is driven by the first stepper motor 33. By setting the worm wheel 36 and worm 37 mechanism, the small-angle rotation of the first wedge 31 and the second wedge 32 can be controlled. With the worm wheel 36 and worm 37 as the transmission device and the optical wedge as the refractive element, the incident laser angle can be precisely adjusted. In the embodiment, the output shaft of the first stepper motor 33 is connected to the worm 37 through a gear set 35; the output shaft of the second stepper motor 34 is connected to the worm 36 through a gear set 35. The worm wheel 36 is embedded in the middle through hole of the adjustment frame, and the end cover is fixed on the outside. The worm wheel can be freely rotated by adjusting the preload. The worm wheel 36 is meshed with the worm 37, and the worm 37 can drive the worm wheel 36 to rotate without friction. The worm wheel 36 fixed to the first wedge block 31 is provided with a mounting hole for the first wedge block 31, and the first wedge block 31 is fixed in the mounting hole of the first wedge block 31 by a pressure ring, and the first wedge block 31 is driven to rotate by the worm wheel 36. The worm 37 is located on one side of the worm wheel 36 and meshes with the worm wheel 36, and the worm 37 and the driving shaft of the first stepper motor 33 are transmitted through the gear set 35. In practical applications, technicians in the field can select the setting direction and gear type of the gears in the gear set 35 as needed. In an optional embodiment, the gears in the gear set 35 are fan-shaped teeth. In addition, a worm gear transmission is adopted between the stepper motor and the wedge block, which has a compact structure and is conducive to reducing the overall installation volume between the air-conditioning light wedge group and the stepper motor as a power device.

[0037] The working steps of the optical fiber automatic coupling device in this embodiment are as follows:

[0038] The first step is to turn on the laser 1 with a wavelength of 780nm, and pass a laser beam with an optical power of 3mw emitted by the laser 1 through the first fiber collimator 2 to make the incident light become a nearly parallel beam with a small divergence angle, and then the beam passes through the adjustable wedge group 3;

[0039] The second step is to allow the laser light passing through the adjustable wedge group 3 to pass through the fiber coupler 4. The output end of the fiber coupler 4 is connected to the optical power detection module 5 with a single-mode optical fiber. At this time, the optical power value collected by the optical power detection module 5 is the laser power coupled into the single-mode optical fiber.

[0040] The third step is to place a photodiode amplifier circuit at the receiving end of the fiber coupler 4, so that the laser passing through the fiber coupler 4 hits the photodiode. By rotating the optical wedge, the incident angle direction of the laser at the input end of the fiber coupler 4 is changed, and the coupling efficiency will also change. As the laser intensity changes, the voltage at the output end of the photodiode amplifier circuit will also change. The voltage at the output end of the photodiode amplifier circuit is collected by the ADC module, and the collected voltage is transmitted to the host computer 8 to be compared with the threshold value.

[0041] The fourth step is to compare the collected value with the threshold to obtain an error value. The host computer 8 transmits the error value to the drive circuit through the control processor 6. The control processor 6 converts the error value into a voltage value, and the drive circuit controls the motor to rotate.

[0042] The fifth step is to continuously iteratively optimize the collected error values ​​through the entire closed-loop feedback control system, so that the real-time value finally reaches the set threshold and maintains long-term stability.

[0043] Embodiment 2:

[0044] This embodiment provides an optical fiber automatic coupling method, which is applied to the optical fiber automatic coupling device shown in Example 1. Figure 3 The method comprises the following steps:

[0045] S1, control laser 1 to output a laser beam, the target optical power value of the laser beam is P 0 , the threshold voltage value corresponding to the target optical power is U 0 ; The threshold voltage value is a predetermined value;

[0046] S2, obtain the optical power output from the optical fiber coupler 4 to the single-mode optical fiber through the optical power detection module 5, and convert it into a voltage value U 1 ; The collected voltage value U 1 The threshold voltage value U corresponding to the target optical power 0 Compare the two, and determine whether it is necessary to compensate for the deviation of the incident light angle based on the difference between the two. If it is necessary to compensate for the deviation of the incident light angle, control the stepper motor to drive the adjustable wedge group 3 to move;

[0047] S3, repeat step S2 until the collected voltage value U 1 Reaching the threshold voltage value U 0 .

[0048] The method in this embodiment is based on the difference between the voltage value collected by the optical power detection module 5 and the expected value as a feedback control signal. Since the laser coupled into the optical fiber is continuously controllable, the signal collected by the optical power detection module 5 is also continuously controllable. Therefore, based on the feedback control signal, the control quantity can be produced in real time and continuously to control the power device of the adjustable optical wedge group 3 in real time.

[0049] In this embodiment, the power device of the adjustable light wedge set 3 is a stepper motor connected to the first wedge block 31 and the second wedge block 32 respectively, and the control processor 6 is connected to the stepper motor through the motor driver 7. In step S2, the stepper motor is controlled to drive the adjustable light wedge set 3 to move, including:

[0050] The control processor 6 uses a timer to generate dual-channel pulse width modulation signals PWM1 and PWM2 of corresponding frequencies, and outputs them to the motor driver 7 by changing the frequencies of PWM1 and PWM2, thereby driving the first motor connected to the first wedge block 31 and the second motor connected to the second wedge block 32 to rotate, so as to realize automatic coupling of the optical fiber.

[0051] like Figure 3 As shown, the specific adjustment method of the control processor 6 to the adjustable wedge group 3 is as follows:

[0052] S21, control the first wedge block 31 to rotate a step angle through the pulse signal PWM1, and wait for the second wedge block 32 to move; S22, continuously give the second wedge block 32 a pulse signal PWM2, and obtain the voltage value collected by the optical power detection module 5 at the end of each PWM2;

[0053] S23, compare the voltage value collected by the optical power detection module 5 with the preset threshold voltage value to determine whether the collected voltage value reaches the threshold voltage value; if so, control the wedge block 2 to stop rotating; if the voltage values ​​collected by the second wedge block 32 after rotating 360° do not reach the threshold voltage value, return to execute step S21.

[0054] In the embodiment, before executing steps S21 - S23 , it is necessary to calculate the transmission ratio between the stepper motor gear and the corresponding worm wheel 37 and worm 36 to determine the set frequencies of PWM1 and PWM2 .

[0055] In the above step S22, for continuous PWM2 signals, with the end of each PWM2 signal as a sign, the ADC module stores the collected voltage values ​​as an array and sends it to the host computer 8, triggering the ADC interrupt to automatically convert and store the voltage values.

[0056] In the above step S23, the host computer 8 compares the collected voltage value with the preset threshold voltage value. Separating the numerical calculation from the control logic of the stepper motor is conducive to data storage and reduces the calculation pressure of the control processor 6, which can improve the execution efficiency and execution stability of the method.

[0057] The optical fiber automatic coupling method of this embodiment uses the optical power detection module 5 to detect the optical power behind the optical fiber in real time, and feeds the signal back to the control processor 6. When the received laser power signal changes, the motor driver 7 and the motor are controlled by the fine-tuning algorithm in real time to change the direction of the incident light, thereby achieving long-term stability of the optical power behind the optical fiber. Therefore, this method can achieve fast real-time automatic alignment coupling of spatial lasers, and maintain long-term high efficiency and stability of coupling efficiency. The constructed closed-loop feedback system can automatically achieve real-time automatic fine-tuning using the fine-tuning algorithm to achieve the best coupling effect.

[0058] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An automatic optical fiber coupling device, characterized in that: It includes a laser and a fiber collimator, an adjustable wedge group, a fiber coupler and an optical power detection module which are sequentially arranged along the direction of the laser beam emission; The adjustable optical wedge group includes a first wedge block and a second wedge block which are sequentially arranged along the incident direction to the emitting direction of the light beam, and the central areas of the first wedge block and the second wedge block are used for passing light; the first wedge block and the second wedge block are respectively driven to move by a first stepper motor and a second stepper motor, and the first stepper motor and the second stepper motor are controlled by a control processor through a motor driver; The optical power detection module is connected to the optical fiber coupler through the single-mode optical fiber, and is used to monitor the optical power coupled into the single-mode optical fiber and convert the monitored optical signal into an electrical signal. The optical power detection module is connected to the control processor; The control processor is used to control the action of the first stepper motor and / or the second stepper motor based on the difference between the actual value collected in real time by the optical power detection module and the threshold voltage value corresponding to the target optical power.

2. The optical fiber automatic coupling device according to claim 1, characterized in that: The control processor comprises an analog-to-digital conversion module, which performs analog-to-digital conversion processing on the electrical signal from the optical power detection module.

3. The optical fiber automatic coupling device according to claim 1, characterized in that: It also includes a host computer, which communicates with the control processor and is used to compare the difference between the actual value collected in real time by the optical power detection module and the threshold voltage value corresponding to the target optical power.

4. The optical fiber automatic coupling device according to claim 1, characterized in that: The first stepper motor and the first wedge block, as well as the second stepper motor and the second wedge block are respectively connected via worm gear transmission.

5. The optical fiber automatic coupling device according to claim 4, characterized in that: A first wedge block mounting hole is provided on the worm wheel fixed with the first wedge block, and the first wedge block is fixed in the first wedge block mounting hole through a pressure ring; a second wedge block mounting hole is provided on the worm wheel fixed with the second wedge block, and the second wedge block is fixed in the second wedge block mounting hole through a pressure ring.

6. The optical fiber automatic coupling device according to claim 1, characterized in that: The receiving end of the optical fiber coupler is provided with a photodiode amplifier circuit, and the output end of the adjustable optical wedge group is connected to the input end of the optical fiber coupler through the photodiode amplifier circuit.

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