Method and device for testing polarization characteristics of semiconductor laser generating device

Abstract

The invention provides a polarization characteristic test method and test device for a semiconductor laser generating device. The method comprises the following steps: driving an electric rotating mirror group to rotate; recording a voltage signal output by the semiconductor light source corresponding to each rotation angle value; voltage signals output by the semiconductor laser generating devices are converted into laser power; correcting each laser power according to the rotation angle of the electric rotating mirror group; based on the corrected power of each laser, the corrected maximum laser power and the corrected minimum laser power are searched and obtained, and the polarization extinction ratio of the semiconductor laser generating device is calculated and obtained according to the corrected maximum laser power and the corrected minimum laser power; and in the polar axis coordinate system, drawing a polarization characteristic spectrum of the semiconductor light source according to the rotation angle of the electric rotating mirror group and the corrected laser power corresponding to the rotation angle. The semiconductor light source polarization characteristic testing efficiency is greatly improved, the constant error of the testing system can be eliminated by correcting the power of the laser, and the testing precision is improved.

Description

Technical Field

[0001] The invention relates to a semiconductor laser generating device, and in particular to a polarization characteristic testing method and a testing device for a semiconductor laser generating device. Background Art

[0002] Semiconductor lasers have the advantages of small size, light weight, high electro-optical conversion efficiency, stable performance, high reliability and long life. They have become the most promising field in the optoelectronic industry and can be widely used in communications, computers (mainly data storage and input and output devices), film and television, manufacturing, aerospace, aviation, material processing, medical, entertainment, scientific research, security protection, military, anti-terrorism, handicrafts, display and printing industries. Testing and characterizing the performance parameters of semiconductor lasers is the key to a deep understanding of laser characteristics, and it is also an important basis for judging the quality of lasers; only in this way can the laser be used correctly and its life be extended. Therefore, it is of great practical significance to research and develop a semiconductor laser characteristic test system with complete test functions.

[0003] Polarization is a very important characteristic of light. In the actual manufacturing process of semiconductor lasers, it is difficult to ensure that the polarization direction of light is completely aligned with the slow axis direction, and there are certain errors that cannot be eliminated. According to the most advanced technology in the world, the minimum angular error that can be achieved is + / -2 degrees, and the smaller the angular error, the higher the accuracy, and both the production cost and the installation cost are very high.

[0004] Furthermore, semiconductor lasers are very sensitive to temperature changes due to their crystal structure and temperature-sensitive properties. Their threshold characteristics and output optical power will also change with changes in operating temperature. The impact of temperature on the performance of semiconductor lasers is mainly reflected in their power stability. Currently, there is usually less attention paid to temperature changes in the polarization processing of lasers. Summary of the invention

[0005] The present invention provides a method and a device for testing polarization characteristics of a semiconductor laser generator, which solves the technical problems of low testing efficiency and low testing accuracy in the prior art of polarization characteristics testing. The technical solution is as follows:

[0006] A method for testing polarization characteristics of a semiconductor laser generating device comprises the following steps:

[0007] S1: Place a collimating lens in the direction of the outgoing light of the semiconductor laser generating device, and install the linear polarizer 30 on the electric rotating mirror assembly and place it behind the collimating lens;

[0008] S2: The electric rotating mirror group can drive the linear polarizer to rotate, and the control processor drives the electric rotating mirror group to rotate, thereby driving the linear polarizer to rotate, and obtaining the voltage signal output by the semiconductor light source through the current preamplifier;

[0009] S3: changing the rotation angle of the electric rotating mirror assembly according to the set step length so that the rotation angle of the electric rotating mirror assembly covers 0° to 360°, and recording the voltage signal output by the semiconductor light source corresponding to each rotation angle value; and recording the temperature signal of the semiconductor light source corresponding to each rotation angle value;

[0010] S4: converting the voltage signal output by each semiconductor light source 10 into laser power;

[0011] S5: Correcting the power of each laser according to the rotation angle of the electric rotating mirror group 4;

[0012] S6: based on the corrected powers of the respective lasers, searching and obtaining the corrected maximum laser power and the corrected minimum laser power; and calculating and obtaining the polarization extinction ratio of the semiconductor light source according to the corrected maximum laser power and the corrected minimum laser power;

[0013] S7: In a polar coordinate system, plotting a polarization characteristic spectrum of the semiconductor light source according to a rotation angle of the electric rotating mirror assembly and a corrected laser power corresponding to the rotation angle;

[0014] S8: Complete the polarization characteristic test of the semiconductor laser generating device according to the polarization extinction ratio and polarization characteristic spectrum of the semiconductor light source.

[0015] Furthermore, in step S4, the conversion relationship between the voltage signal output by the semiconductor laser generating device and the laser power is: Wherein, D(φ) is the voltage signal output by the semiconductor laser, and k is the proportional coefficient between the laser power and the voltage signal.

[0016] Further, in step S5, when 0°≤φ<180°, the laser power P(φ) is adjusted according to Correction; when 180°≤φ<360°, the laser power P(φ) is based on Correction is performed, where P'(φ) is the laser power after correction and P(φ) is the laser power before correction.

[0017] Further, in step S6, the polarization extinction ratio PER of the semiconductor laser generating device can be calculated according to Calculate and obtain, where P max ' is the corrected maximum laser power, P min ' is the corrected minimum laser power.

[0018] Furthermore, after step S8, the following steps are also included:

[0019] S9: drawing a temperature deviation characteristic spectrum of the semiconductor light source according to the temperature signal of the semiconductor light source, in combination with the rotation angle of the electric rotating mirror group and the corrected laser power corresponding to the rotation angle;

[0020] S10: completing the temperature-bias characteristic test of the semiconductor laser generating device according to the polarization extinction ratio and temperature-bias characteristic spectrum of the semiconductor light source.

[0021] Furthermore, in step S9, a temperature deviation characteristic spectrum of the semiconductor light source is drawn according to the rotation angle of the electric rotating mirror group, the corrected laser power corresponding to the rotation angle, the temperature of the semiconductor light source corresponding to the rotation angle, and the working current of the semiconductor laser corresponding to the rotation angle.

[0022] A polarization characteristic testing device for a semiconductor laser generating device comprises a semiconductor laser generating device, a collimating lens, a linear polarizer, an electric rotating mirror group, a photodetector, a current preamplifier and a control processor. The semiconductor laser generating device is used to output laser light. The collimating lens, the linear polarizer, the photodetector and the current preamplifier are sequentially arranged along the laser emission direction. The linear polarizer is mounted on the electric rotating mirror group and can rotate along the laser optical axis. The control processor is connected to the electric rotating mirror group and the current preamplifier.

[0023] The semiconductor laser generating device includes a semiconductor light source driver and a semiconductor light source. The semiconductor light source driver is electrically connected to the semiconductor light source and is used to provide a driving current to the semiconductor light source and to perform temperature control on the semiconductor light source. The semiconductor laser generating device is provided with a temperature sensor for detecting the temperature of the semiconductor light source and sending the temperature information to a control processor.

[0024] The semiconductor laser generating device also includes a current sensor for detecting the operating current of the semiconductor light source and sending a current signal to the control processor.

[0025] The control processor includes a data acquisition card and a host computer. The data acquisition card is used to convert the voltage signal output by the current preamplifier into a digital signal and send the digital signal to the host computer. The host computer is used to control the electric rotating mirror group, and calculate the polarization characteristic quantitative index of the semiconductor light source according to the voltage signal provided by the current preamplifier and the rotation angle of the electric rotating mirror group, and calculate the temperature deviation characteristic quantitative index of the semiconductor light source affected by temperature according to the polarization characteristic quantitative index and the temperature signal of the semiconductor light source.

[0026] The polarization characteristic testing method and testing device of the semiconductor laser generating device improve the polarization characteristic testing efficiency of the semiconductor laser generating device, and can eliminate the constant value error of the testing system and improve the testing accuracy by correcting the laser power. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a structural schematic diagram of a polarization characteristic testing device for the semiconductor laser generating device;

[0028] Figure 2 It is a schematic flow chart of a method for testing polarization characteristics of the semiconductor laser generating device;

[0029] The following reference numerals are included:

[0030] 10. Semiconductor laser generating device; 20. Collimating lens; 30. Linear polarizer; 40. Electric rotating mirror group; 41. Electric rotating mirror frame; 42. Electric rotating mirror frame controller; 50. Photodetector; 60. Current preamplifier; 70. Control processor; 71. Data acquisition card; 72. Host computer; 80. Temperature sensor. DETAILED DESCRIPTION

[0031] like Figure 1 As shown, the polarization characteristic testing device of the semiconductor laser generating device comprises a semiconductor laser generating device 10, a collimating lens 20, a linear polarizer 30, an electric rotating mirror group 40, a photodetector 50, a current preamplifier 60 and a control processor 70. The semiconductor laser generating device 10 is used to output laser light. Along the laser emission direction, the collimating lens 20, the linear polarizer 30, the photodetector 50 and the current preamplifier 60 are sequentially arranged. The linear polarizer 30 is mounted on the electric rotating mirror group 40 and can rotate along the laser optical axis. The control processor 70 is connected to the electric rotating mirror group 40 and the current preamplifier 60.

[0032] The semiconductor laser generating device 10 includes a semiconductor light source driver and a semiconductor light source, the semiconductor light source driver is electrically connected to the semiconductor light source, and the semiconductor light source driver is used to provide a driving current to the semiconductor light source and to perform temperature control on the semiconductor light source. The semiconductor laser generating device 10 is provided with a temperature sensor 80 for detecting the temperature of the semiconductor light source and sending the temperature information to the control processor 70.

[0033] The collimating lens 20 is disposed in the direction of the emitted light of the semiconductor light source, and is used to collimate the output laser.

[0034] The linear polarizer 30 is arranged on the electric rotating mirror group 40, and the linear polarizer 30 is used to polarize the collimated parallel laser into linear polarized light, and the electric rotating mirror group 40 is used to drive the linear polarizer 30 to rotate. Further, the electric rotating mirror group 40 includes an electric rotating mirror frame and an electric rotating mirror frame controller, the linear polarizer 30 is arranged on the electric rotating mirror frame, the electric rotating mirror frame controller is used to control the rotation of the electric rotating mirror frame, and the electric rotating mirror frame is provided with a stepping motor, which can make the linear polarizer 30 perform stepping rotation within a circumferential range, and rotate along the laser optical axis during rotation, and the laser optical axis is the optical axis formed by the laser emission.

[0035] The photodetector 50 is used to convert linearly polarized light into a current signal, and the current preamplifier 60 is used to convert the current signal into a voltage signal and amplify the voltage signal.

[0036] The control processor 70 controls the electric rotating mirror group and the semiconductor laser generating device 10. The control processor 70 is used to send control instructions to the electric rotating mirror frame controller and receive feedback information from the electric rotating mirror frame controller; it is also used to send switch control instructions to the semiconductor laser generating device 10 and receive feedback information from the temperature sensor 80. Further, the control processor 70 includes a data acquisition card and a host computer. The data acquisition card is used to convert the voltage signal output by the current preamplifier into a digital signal and send the digital signal to the host computer. The host computer is used to control the electric rotating mirror group, and calculate the polarization characteristic quantitative index of the semiconductor light source according to the voltage signal provided by the current preamplifier 60 and the rotation angle of the electric rotating mirror group, and calculate the temperature deviation characteristic quantitative index of the semiconductor light source affected by temperature according to the polarization characteristic quantitative index and the temperature signal of the semiconductor light source.

[0037] like Figure 2 As shown, according to the polarization characteristic testing device of the semiconductor laser generating device, a polarization characteristic testing method of the semiconductor laser generating device is implemented, comprising the following steps:

[0038] S1: placing the collimating lens 20 in the direction of the outgoing light of the semiconductor laser generating device 10, installing the linear polarizer 30 on the electric rotating mirror group 40 and placing it behind the collimating lens 20;

[0039] S2: the electric rotating mirror group can drive the linear polarizer 30 to rotate, the control processor 70 drives the electric rotating mirror group 40 to rotate, and then drives the linear polarizer 30 to rotate, and obtains the voltage signal output by the semiconductor light source 10 through the current preamplifier 60;

[0040] S3: changing the rotation angle of the electric rotating mirror assembly 40 according to the set step length, so that the rotation angle of the electric rotating mirror assembly 40 covers 0° to 360°, and recording the voltage signal output by the semiconductor light source 10 corresponding to each rotation angle value; and recording the temperature signal of the semiconductor light source 10 corresponding to each rotation angle value;

[0041] S4: converting the voltage signal output by each semiconductor light source 10 into laser power;

[0042] The conversion relationship between the voltage signal output by the semiconductor laser generator and the laser power is: Wherein, D(φ) is the voltage signal output by the semiconductor laser, and k is the proportional coefficient between the laser power and the voltage signal.

[0043] S5: Correcting the power of each laser according to the rotation angle of the electric rotating mirror assembly 40;

[0044] The laser power can be corrected according to the rotation angle of the electric rotating mirror group: when 0°≤φ<180°, the laser power P(φ) can be corrected according to Correction; when 180°≤φ<360°, the laser power P(φ) can be adjusted according to Correction is performed, where P'(φ) is the laser power after correction and P(φ) is the laser power before correction.

[0045] S6: based on the corrected powers of the respective lasers, find and obtain the corrected maximum laser power and the corrected minimum laser power; calculate and obtain the polarization extinction ratio of the semiconductor light source 10 according to the corrected maximum laser power and the corrected minimum laser power;

[0046] The polarization extinction ratio PER of a semiconductor laser generator can be calculated based on Calculate and obtain, where P max ' is the corrected maximum laser power, P min ' is the corrected minimum laser power.

[0047] S7: In the polar coordinate system, a polarization characteristic spectrum of the semiconductor light source 10 is drawn according to the rotation angle of the electric rotating mirror assembly 40 and the corrected laser power corresponding to the rotation angle;

[0048] S8: Complete the polarization characteristic test of the semiconductor laser generating device 10 according to the polarization extinction ratio and polarization characteristic spectrum of the semiconductor light source 10.

[0049] Furthermore, the method further comprises the following steps:

[0050] S9: drawing a temperature deviation characteristic spectrum of the semiconductor light source 10 according to the temperature signal of the semiconductor light source 10, combined with the rotation angle of the electric rotating mirror group 40 and the corrected laser power corresponding to the rotation angle;

[0051] The variation of laser output power is mainly caused by the variation of external differential quantum efficiency and threshold current due to temperature change. The output power of semiconductor laser can generally be expressed by the following formula:

[0052]

[0053] Where P0 represents the optical power; η D represents the external differential quantum power, which is inversely proportional to the temperature change. The change amplitude can be ignored during calculation; h represents Planck's constant; V represents the light frequency; e0 represents a single electron; I represents the working current given to the laser by the driving system; I th Represents the laser threshold current.

[0054] When the injected current remains constant, the threshold current I th The external differential quantum efficiency changes under the influence of temperature. Changes in these two situations will cause changes in output power. In short, when a semiconductor laser is working, it is impossible to convert all electrical energy into light, because it will cause certain losses, such as non-radiative mixing, non-radiative mixing, etc., which will turn part of the electrical energy into heat, thereby increasing the chip temperature of the semiconductor laser. As the grain temperature increases, the output power of the laser decreases, the central wavelength redshifts, and the PI curve exhibits nonlinear distortion. A temperature control circuit is added to the design of the laser driver to ensure the stability of the laser operation, or to indirectly control the output wavelength of the semiconductor laser by controlling the temperature.

[0055] In this case, the influence of the temperature of the laser needs to be considered. Therefore, on the basis of the polarization characteristic spectrum, the temperature of the semiconductor light source needs to be added to realize a temperature-polarization characteristic spectrum that can reflect the influence of temperature.

[0056] Assuming the temperature of the semiconductor light source is T, a temperature deviation characteristic graph of the semiconductor light source 10 is plotted based on the rotation angle of the electric rotating mirror assembly 40, the corrected laser power corresponding to the rotation angle, the temperature of the semiconductor light source corresponding to the rotation angle, and the operating current of the semiconductor laser corresponding to the rotation angle.

[0057] S10: completing the temperature-bias characteristic test of the semiconductor laser generating device 10 according to the polarization extinction ratio and temperature-bias characteristic spectrum of the semiconductor light source.

[0058] Compared with the prior art, the present invention greatly improves the testing efficiency of polarization characteristics and temperature deviation characteristics of semiconductor light sources, and can eliminate the constant value error of the testing system and improve the testing accuracy by correcting the laser power.

Claims

1. A method for testing polarization characteristics of a semiconductor laser generating device, comprising the following steps: S1: Place a collimating lens in the direction of the outgoing light of the semiconductor laser generating device, and install the linear polarizer 30 on the electric rotating mirror assembly and place it behind the collimating lens; S2: The electric rotating mirror group can drive the linear polarizer to rotate, and the control processor drives the electric rotating mirror group to rotate, thereby driving the linear polarizer to rotate, and obtaining the voltage signal output by the semiconductor light source through the current preamplifier; S3: changing the rotation angle of the electric rotating mirror assembly according to the set step length so that the rotation angle of the electric rotating mirror assembly covers 0° to 360°, and recording the voltage signal output by the semiconductor light source corresponding to each rotation angle value; and recording the temperature signal of the semiconductor light source corresponding to each rotation angle value; S4: converting the voltage signal output by each semiconductor light source 10 into laser power; S5: Correcting the power of each laser according to the rotation angle of the electric rotating mirror group 4; S6: based on the corrected powers of the respective lasers, searching and obtaining the corrected maximum laser power and the corrected minimum laser power; and calculating and obtaining the polarization extinction ratio of the semiconductor light source according to the corrected maximum laser power and the corrected minimum laser power; S7: In a polar coordinate system, plotting a polarization characteristic spectrum of the semiconductor light source according to a rotation angle of the electric rotating mirror assembly and a corrected laser power corresponding to the rotation angle; S8: Complete the polarization characteristic test of the semiconductor laser generating device according to the polarization extinction ratio and polarization characteristic spectrum of the semiconductor light source.

2. The method for testing polarization characteristics of a semiconductor laser generator according to claim 1, characterized in that: In step S4, the conversion relationship between the voltage signal output by the semiconductor laser generating device and the laser power is: Wherein, D(φ) is the voltage signal output by the semiconductor laser, and k is the proportional coefficient between the laser power and the voltage signal.

3. The method for testing polarization characteristics of a semiconductor laser generator according to claim 1, characterized in that: In step S5, when 0°≤φ<180°, the laser power P(φ) is adjusted according to Correction; when 180°≤φ<360°, the laser power P(φ) is based on Correction is performed, where P'(φ) is the laser power after correction and P(φ) is the laser power before correction.

4. The method for testing polarization characteristics of a semiconductor laser generator according to claim 1, characterized in that: In step S6, the polarization extinction ratio PER of the semiconductor laser generating device can be calculated according to Calculate and obtain, where P max ' is the corrected maximum laser power, P min ' is the corrected minimum laser power.

5. The method for testing polarization characteristics of a semiconductor laser generator according to claim 1, characterized in that: After step S8, the following steps are also included: S9: drawing a temperature deviation characteristic spectrum of the semiconductor light source according to the temperature signal of the semiconductor light source, in combination with the rotation angle of the electric rotating mirror group and the corrected laser power corresponding to the rotation angle; S10: completing the temperature-bias characteristic test of the semiconductor laser generating device according to the polarization extinction ratio and temperature-bias characteristic spectrum of the semiconductor light source.

6. The method for testing polarization characteristics of a semiconductor laser generator according to claim 5, characterized in that: In step S9, a temperature deviation characteristic spectrum of the semiconductor light source is drawn according to the rotation angle of the electric rotating mirror group, the corrected laser power corresponding to the rotation angle, the temperature of the semiconductor light source corresponding to the rotation angle, and the working current of the semiconductor laser corresponding to the rotation angle.

7. A polarization characteristic testing device for a semiconductor laser generator, characterized in that: The invention comprises a semiconductor laser generating device, a collimating lens, a linear polarizer, an electric rotating mirror group, a photodetector, a current preamplifier and a control processor. The semiconductor laser generating device is used to output laser light. The collimating lens, the linear polarizer, the photodetector and the current preamplifier are sequentially arranged along the laser emission direction. The linear polarizer is installed on the electric rotating mirror group and can rotate along the laser optical axis. The control processor is connected with the electric rotating mirror group and the current preamplifier.

8. The polarization characteristic testing device of a semiconductor laser generator according to claim 7, characterized in that: The semiconductor laser generating device includes a semiconductor light source driver and a semiconductor light source. The semiconductor light source driver is electrically connected to the semiconductor light source and is used to provide a driving current to the semiconductor light source and to perform temperature control on the semiconductor light source. The semiconductor laser generating device is provided with a temperature sensor for detecting the temperature of the semiconductor light source and sending the temperature information to a control processor.

9. The polarization characteristic testing device of a semiconductor laser generator according to claim 8, characterized in that: The semiconductor laser generating device also includes a current sensor for detecting the operating current of the semiconductor light source and sending a current signal to the control processor.

10. The polarization characteristic testing device of a semiconductor laser generator according to claim 7, characterized in that: The control processor includes a data acquisition card and a host computer. The data acquisition card is used to convert the voltage signal output by the current preamplifier into a digital signal and send the digital signal to the host computer. The host computer is used to control the electric rotating mirror group, and calculate the polarization characteristic quantitative index of the semiconductor light source according to the voltage signal provided by the current preamplifier and the rotation angle of the electric rotating mirror group, and calculate the temperature deviation characteristic quantitative index of the semiconductor light source affected by temperature according to the polarization characteristic quantitative index and the temperature signal of the semiconductor light source.

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