Optical path coupling alignment method for external-cavity semiconductor laser

Abstract

The application provides a kind of optical path coupling alignment method of external cavity semiconductor laser, comprising the following steps: adjusting the position and angle of optical fiber, so that the optical fiber is coupled with semiconductor laser chip;Adjust the position and angle of collimating lens, so that the invisible laser emitted by semiconductor laser chip is collimated through collimating lens;Place a visible light laser on one side of the semiconductor laser chip, adjust the position and angle of the visible light laser, so that the visible laser emitted by the visible light laser is parallel to the invisible laser;Adjust the position and angle of the mirror, so that the visible laser emitted by the adjusted visible light laser is reflected along the original optical path after the mirror, keep the angle of the mirror unchanged, adjust the position of the mirror, and translate the mirror to the laser optical axis of the semiconductor laser chip.In the specific operation process of coupling alignment of the application, optical method, mechanical method and space geometry are combined, which effectively reduces the alignment difficulty of optical path coupling and improves the operation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical path coupling, and particularly relates to an optical path coupling alignment method of an external cavity semiconductor laser. BACKGROUND

[0002] The external cavity semiconductor laser has the advantages of low noise, high side mode suppression ratio, high temperature stability, wide wavelength tuning range, narrow linewidth, etc. It has a wide application in the fields of optical communication, laser radar, spectral analysis, optical coherence tomography, environmental monitoring, atomic clock, etc. However, in the manufacturing process of the external cavity semiconductor laser, the optical path coupling alignment between the discrete devices in the laser system is often an important technical difficulty and a key factor restricting the quality and production efficiency of the finished product of the external cavity semiconductor laser. In addition, different external cavity semiconductor lasers generally have different structural characteristics and use different devices. Therefore, in the process of coupling the optical paths of the devices of different external cavity semiconductor lasers, the methods and operation steps used are different, and lack of uniformity and standardization, which further increases the difficulty of the optical path coupling alignment of the external cavity semiconductor laser. Such characteristics determine that the optical path coupling of each external cavity semiconductor laser often needs to be gradually explored by engineers, which has strong experience dependence and seriously restricts the development of the external cavity semiconductor laser industry.

[0003] Although the device composition of the external cavity semiconductor laser and the required optical path coupling method are different, some devices are suitable for most external cavity semiconductor lasers, such as optical fibers, semiconductor laser chips, collimating lenses, mirrors, etc., which are also often used in other optical path designs. Therefore, for the optical path coupling alignment between these commonly used devices, a universal coupling operation method can be proposed. However, at present, most of such technologies are designed for a specific laser structure and do not have universal applicability, such as the following cases:

[0004] Most of the existing collimation methods of semiconductor laser chips and lenses are direct visual methods, which adjust the lens according to experience by directly observing the change of the light spot. However, it is difficult to observe the non-visible light, and in the case of a large divergence angle of the laser chip and a very small power, such as a semiconductor optical amplifier chip with a divergence angle of 40° and spontaneous emission light of only a few hundred μW, it is difficult to observe the light spot before the lens completes the beam collimation, and the lens adjustment is difficult.

[0005] The existing coupling method of semiconductor laser chip and optical fiber is mostly visual method without using lens for beam shaping and focusing, which adjusts the position of optical fiber according to experience by directly observing the output result of the fiber end or the chip end. However, this method has low operation efficiency and often leads to low coupling precision and large loss, especially in the case of small size waveguide, which cannot effectively couple the light into the waveguide. If lens is used for beam shaping and focusing, the coupling complexity is increased, which is not suitable for the application scenarios with high requirements for system simplicity, convenience and variability, such as temporary coupling of seed light source output by optical fiber and semiconductor laser chip.

[0006] Most of the existing methods for adjusting the perpendicularity of laser beam and reflecting cavity surface adopt the method of directly observing the direction of reflected laser to adjust the reflecting cavity surface. However, it is difficult to directly observe the reflected light path in the case of non-visible waveband laser.

[0007] Most of the existing methods for adjusting the parallelism of two laser beams adopt the method of fixing one laser beam in vertical direction or horizontal direction and adjusting the other laser beam. However, if one of the laser beams is in inclined direction and there is a fixed requirement for the placement position of the two lasers, it is difficult to adjust the parallelism when the two lasers are placed together. SUMMARY

[0008] The purpose of the present application is to overcome the defects of the prior art and provide an optical path coupling alignment method for external cavity semiconductor laser, which effectively reduces the alignment difficulty of optical path coupling and improves the operation efficiency by combining optical method, mechanical method and spatial geometry in the specific operation process of coupling of optical fiber and semiconductor laser chip, collimation of invisible laser emitted by semiconductor laser chip through collimating lens, parallel alignment of visible laser and invisible laser and perpendicularity of reflecting mirror and visible laser.

[0009] To achieve the above purpose, the present application adopts the following specific technical solutions:

[0010] The optical path coupling alignment method for external cavity semiconductor laser provided by the present application includes semiconductor laser chip, collimating lens and reflecting mirror arranged in sequence, and includes the following steps:

[0011] Adjust the position and angle of the optical fiber to couple the optical fiber with the semiconductor laser chip;

[0012] Adjust the position and angle of the collimating lens to collimate the invisible laser emitted by the semiconductor laser chip through the collimating lens;

[0013] Place a visible light laser on one side of the semiconductor laser chip and adjust the angle of the visible light laser to make the visible laser emitted by the visible light laser parallel to the invisible laser;

[0014] The position and angle of the reflecting mirror are adjusted so that the visible laser emitted by the adjusted visible laser is reflected along the original light path, the angle of the reflecting mirror is kept unchanged, and the position of the reflecting mirror is adjusted so that the reflecting mirror is translated to the laser optical axis of the semiconductor laser chip.

[0015] Preferably, the position and angle of the optical fiber are adjusted so that the optical fiber is coupled with the semiconductor laser chip in the following specific process:

[0016] Coarse adjustment stage:

[0017] The yaw angle of the optical fiber is adjusted so that the direction of the optical fiber is consistent with the incident waveguide direction of the waveguide structure in the semiconductor laser chip;

[0018] The pitch angle of the optical fiber is adjusted so that the direction of the optical fiber is consistent with the horizontal direction of the semiconductor laser chip;

[0019] The position of the optical fiber is adjusted so that the tip of the optical fiber is aligned with the light inlet of the waveguide structure;

[0020] Fine adjustment stage:

[0021] A light power meter is placed at the end of the semiconductor laser chip away from the optical fiber;

[0022] The position of the optical fiber is adjusted until the light power monitored by the light power meter shows a jump increase, and then the adjustment of the optical fiber is stopped, and the left-right and up-down positions of the optical fiber are fine-adjusted based on the position of the optical fiber at this time, and the highest points of the light power are found in the two directions respectively;

[0023] The pitch angle and the yaw angle of the optical fiber are adjusted until the light power monitored by the light power meter is maximum.

[0024] Preferably, the position and angle of the collimating lens are adjusted so that the invisible laser emitted by the semiconductor laser chip is collimated by the collimating lens in the following specific process:

[0025] The collimating lens is fixed on the adjusting frame, and a CCD camera is placed in the transmission direction of the collimating lens;

[0026] The position and angle of the collimating lens are coarsely adjusted so that the invisible laser emitted by the semiconductor laser chip is clearly imaged in the CCD camera after passing through the collimating lens;

[0027] The pitch angle and the yaw angle of the collimating lens are fine-adjusted so that the peak position of the light spot and the centroid position of the light spot coincide, and then the left-right and up-down positions of the collimating lens are fine-adjusted until the light spot position no longer changes when the CCD camera is moved, and the adjustment of the laser optical axis passing through the center of the collimating lens is completed;

[0028] Adjust the front and back positions of the collimating lens relative to the semiconductor laser chip until the spot size no longer changes when the CCD camera is moved, and the adjustment of the collimating lens being at the laser focal length is completed.

[0029] Preferably, the angle of the visible light laser is adjusted so that the visible laser emitted by the visible light laser is parallel to the invisible laser, and the specific process is as follows:

[0030] Place the CCD camera at the initial position, record the imaging position of the invisible laser emitted by the semiconductor laser chip after collimation by the collimating lens in the CCD camera, and mark it as coordinate A;

[0031] Move the CCD camera by a distance d towards or away from the collimating lens, record the imaging position of the invisible laser in the CCD camera at this time, and mark it as coordinate B;

[0032] Adjust the angle of the visible light laser so that the visible laser emitted by the visible light laser is imaged in the CCD camera, record the imaging position of the visible laser in the CCD camera at this time, and mark it as coordinate A';

[0033] Move the CCD camera by a distance d towards or away from the collimating lens, record the imaging position of the visible laser in the CCD camera at this time, and mark it as coordinate B';

[0034] Adjust the yaw angle and pitch angle of the visible light laser so that the slope between coordinates A' and B' is the same as the slope between coordinates A and B.

[0035] Preferably, the position and angle of the mirror are adjusted so that the visible laser emitted by the adjusted visible light laser is incident on the mirror and reflected along the original light path, and the specific process is as follows:

[0036] Adjust the position of the mirror so that the visible laser of the adjusted visible light laser is incident on the mirror;

[0037] Observe the reflected laser reflected by the mirror, adjust the yaw angle and pitch angle of the mirror so that the reflected laser returns along the incident light path, and is incident on the light outlet of the visible light laser, at this time the mirror is perpendicular to the laser optical axis of the visible light laser.

[0038] Compared with the prior art, the present application can achieve the following technical effects:

[0039] 1、The method of coupling the optical fiber and the semiconductor laser chip in advance to assist the collimation of the collimating lens can effectively reduce the difficulty of lens collimation of large divergence angle and low power laser beam, and improve the collimation efficiency.

[0040] 2、The optical path coupling operation method between the optical fiber and the semiconductor laser chip can effectively improve the coupling efficiency and reduce the loss.

[0041] 3、The light path collimation operation of the laser chip and the collimation lens can effectively improve the light beam collimation effect and the collimation operation efficiency.

[0042] 4、The method for adjusting the reflector by using the visible laser can effectively solve the problem that the reflector angle is difficult to align and the effective resonant cavity cannot be formed due to the invisible laser emitted by the semiconductor laser chip or the low initial optical power of the laser.

[0043] 5、The method for adjusting the parallelism between different laser beams by using the spatial relative position relationship of the visible laser and the invisible laser in the same reference coordinate system can effectively improve the parallelism precision of the two laser beams and improve the operation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a direction diagram of a light path coupling alignment method of an external cavity semiconductor laser according to an embodiment of the present application;

[0045] Figure 2 is a structural diagram of an external cavity semiconductor laser according to an embodiment of the present application;

[0046] Figure 3 is a flow diagram of a light path coupling alignment method of an external cavity semiconductor laser according to an embodiment of the present application;

[0047] Figure 4 is a coupling alignment mode diagram of an optical fiber and a semiconductor laser chip according to an embodiment of the present application;

[0048] Figure 5 is a collimation mode diagram of an invisible laser and a collimation lens and a parallel alignment mode diagram of a visible laser and an invisible laser according to an embodiment of the present application;

[0049] Figure 6 is a light spot diagram observed by a CCD camera during adjustment of a collimation lens according to an embodiment of the present application;

[0050] Figure 7 is a relative relationship diagram of imaging positions of a visible laser and an invisible laser on a CCD camera according to an embodiment of the present application;

[0051] Figure 8 is an adjustment mode diagram of a reflector perpendicular to a visible laser optical axis according to an embodiment of the present application.

[0052] The reference numerals in the drawing include: optical fiber 1, semiconductor laser chip 2, collimating lens 3, mirror 4, optical power meter 5, visible laser 6, CCD camera 7, waveguide structure 8, laser spot peak position 9, laser spot centroid position 10. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0054] In order to make the objects, technical solutions, and advantages of the present application clearer, further detailed descriptions will be given below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not constitute a limitation on the present application.

[0055] The optical path coupling alignment method for the external cavity semiconductor laser provided by the embodiment of the present application is used to realize the coupling alignment between the devices in the external cavity semiconductor laser.

[0056] Figure 1 The azimuth in the optical path coupling alignment method for the external cavity semiconductor laser provided by the embodiment of the present application is shown.

[0057] As shown in Figure 1 , the front, back, left, right, up, down, yaw angle, and pitch angle mentioned in the following method are defined according to Figure 1 .

[0058] Figure 2 The structure of the external cavity semiconductor laser provided by the embodiment of the present application is shown.

[0059] As shown in Figure 2 , the external cavity semiconductor laser includes the semiconductor laser chip 2, the collimating lens 3, and the mirror 4 arranged in sequence, the semiconductor laser chip 2 can be a semiconductor optical amplifier laser chip or a common laser chip, and its function is to provide gain for the external cavity semiconductor laser; the function of the collimating lens 3 is to collimate the divergent laser emitted by the semiconductor laser chip 2; the function of the mirror 4 is to serve as the resonant cavity surface of the external cavity semiconductor laser, and the laser collimated by the collimating lens 3 is reflected back along the original light path to form a resonance.

[0060] In the process of coupling and aligning the optical path of the external cavity semiconductor laser, the devices used include a visible laser 6 and a CCD camera 7. The visible laser 6 is used to provide laser in the visible light band, and the visible laser is adjusted to be parallel to the invisible laser emitted by the semiconductor laser chip 2. The CCD camera 7 is used to observe the shape of the laser spot emitted by the collimating lens 3, and assist in the collimating operation of the collimating lens 3. In the process of adjusting the parallelism between different lasers, the CCD camera 7 is used to observe the positions of the two lasers, determine the directions of the lasers, and assist in the laser parallelism adjustment operation.

[0061] The coupling and alignment method of the external cavity semiconductor laser provided by the embodiment of the application actually includes the following aspects:

[0062] (1) Coupling and alignment of the optical fiber 1 and the semiconductor laser chip 2

[0063] The optical fiber 1 can be an output optical fiber of a seed light source, or an output optical fiber of the external cavity semiconductor laser. When the optical fiber 1 is used as the output optical fiber of the seed light source, the function is to couple the output laser into the semiconductor laser chip 2, and improve the output power of the semiconductor laser chip 2. When the optical fiber 1 is used as the output optical fiber of the external cavity semiconductor laser, the function is to couple the laser output by the semiconductor laser chip 2 into the optical fiber 1.

[0064] The optical fiber 1 is placed at the input end of the semiconductor laser chip 2, the optical fiber 1 adopts a tapered optical fiber output, the positions of the optical fiber 1 and the semiconductor laser chip 2 are observed by using a visual system, and the tip of the optical fiber 1 and the waveguide structure 8 of the semiconductor laser chip 2 are roughly aligned. A light power meter 5 is placed at the other end of the semiconductor laser chip 2, and the light power output by the semiconductor laser chip 2 on the side of the collimating lens 3 is monitored. By cooperating with the light power change rule, the front and back, up and down, left and right, pitch angle and yaw angle of the position of the optical fiber 1 are sequentially adjusted. When the light power output by the semiconductor laser chip 2 is observed to jump and rapidly increase to the maximum, it means that the coupling of the optical fiber 1 and the semiconductor laser chip 2 is completed. Similarly, when the laser output by the semiconductor laser chip 2 needs to be coupled into the optical fiber 1, the above-mentioned optical fiber adjustment method can also be used.

[0065] (2) Collimating alignment of the semiconductor laser chip 2 and the collimating lens 3

[0066] Firstly, the collimating lens 3 is placed at an angle substantially perpendicular to the laser optical axis on the side of the semiconductor laser chip 2 requiring collimation, and then the collimating lens 3 is fixed on the adjusting frame, the up-down, front-back, left-right positions of the collimating lens 3 are adjusted, so that the center of the collimating lens 3 is substantially at the focal length position of the laser optical axis, and the coarse adjustment of the collimating lens 3 is completed. The CCD camera 7 is placed at the end of the collimating lens 3 away from the semiconductor laser chip 2, the shape of the collimated light spot is observed, the front-back, up-down, left-right, pitch angle and yaw angle of the collimating lens 3 are sequentially mechanically adjusted according to the change rule of the light spot, so that the peak position of the light spot coincides with the centroid position of the light spot, and during the front-back translation of the CCD camera 7, the position and size of the light spot remain unchanged, and the collimation alignment of the collimating lens 3 is completed.

[0067] (3) Parallel adjustment of the visible laser emitted by the visible laser 6 and the invisible laser emitted by the semiconductor laser chip 2

[0068] The relative position change of the two laser spots when the CCD camera 7 moves the same distance is observed by using the same CCD camera 7, so as to adjust the angle of the visible laser 6. According to the principle that as long as the relative coordinates change consistently (the spatial slope is consistent) when two straight lines propagate the same distance in the same reference system, the two straight lines must be parallel, the visible laser output by the visible laser 6 is adjusted to be parallel to the invisible laser emitted by the semiconductor laser chip 2.

[0069] (4) Vertical alignment of the mirror 4 and the laser optical axis of the visible laser 6

[0070] The pitch angle and the yaw angle of the mirror 4 are adjusted by using the parallel visible laser 6, until the laser reflected by the mirror 4 is observed to return along the original path of incidence, and then the mirror 4 can be ensured to be vertical to the laser optical axis of the visible laser 6, that is, vertical to the laser optical axis of the semiconductor laser chip 2. At this time, the mirror 4 is translated to the laser optical axis of the semiconductor laser chip 2, so as to form a resonance, and the construction of the external cavity semiconductor laser is completed.

[0071] Figure 3 The flow of the optical path coupling alignment method of the external cavity semiconductor laser provided by the embodiment of the present application is shown.

[0072] As shown in Figure 3 The optical path coupling alignment method of the external cavity semiconductor laser provided by the embodiment of the present application comprises the following steps:

[0073] S1, the position and angle of the optical fiber are adjusted, so that the optical fiber is coupled with the semiconductor laser chip.

[0074] Figure 4 The coupling alignment mode of the optical fiber and the semiconductor laser chip provided by the embodiment of the present application is shown.

[0075] As shown in Figure 4 adjust the yaw angle of the optical fiber 1, so that the direction of the optical fiber 1 is consistent with the incident waveguide direction of the waveguide structure 8 in the semiconductor laser chip 2; adjust the pitch angle of the optical fiber 1, so that the direction of the optical fiber is consistent with the horizontal direction of the semiconductor laser chip 2; adjust the left-right position and the up-down height of the optical fiber 1, so that the tip of the optical fiber is aligned with the light inlet of the waveguide structure 8; adjust the front-back position of the optical fiber 1 until the distance from the semiconductor laser chip 2 is 1-2 mm, and complete the coarse alignment of the optical fiber 1 and the semiconductor laser chip 2.

[0076] Observe the optical power detected by the optical power meter 5 to assist in completing the fine alignment of the optical fiber 1 and the semiconductor laser chip 2. More specifically, first, move the optical fiber 1 left and right in a fine adjustment manner, and after each left-right movement, move the optical fiber 1 up and down in a scanning manner. When the optical fiber 1 deviates from the position of the waveguide structure 8, continue to adjust in the opposite direction. When a large increase in the optical power monitored by the power meter 5 is observed during the adjustment of the optical fiber 1, stop adjusting the optical fiber 1. Take the position of the optical fiber 1 at this time as the reference point, and fine-tune the left-right and up-down positions of the optical fiber 1. In each direction, determine the position of the point with the highest optical power. At this time, it can be considered that the optical fiber 1 has found the light inlet of the waveguide structure 8, that is, the up-down and left-right positions of the optical fiber 1 have been aligned with the light inlet of the waveguide structure 8.

[0077] Adjust the pitch angle of the optical fiber 1, and note that the up-down position and the front-back position of the optical fiber 1 should be returned after each adjustment. Observe the trend of the optical power during the adjustment process. When the optical power is maximum, the pitch angle can be considered to be aligned. Adjust the yaw angle of the optical fiber 1 in the same way, and note that the left-right position and the front-back position should be returned after each adjustment angle.

[0078] According to the requirement of optical power, adjust the front-back position of the optical fiber 1 relative to the semiconductor laser chip 2. When the required coupling loss is as low as possible and the power is as high as possible, the optical fiber 1 should be close to the semiconductor laser chip 2, but cannot touch it. At this time, the coupling alignment of the optical fiber 1 and the semiconductor laser chip 2 is completed.

[0079] S2, adjust the position and angle of the collimating lens, so that the invisible laser emitted by the semiconductor laser chip is collimated with the collimating lens.

[0080] Figure 5 The collimation mode of the invisible laser and the collimating lens provided by the embodiment of the application is shown.

[0081] As shown in Figure 5As shown, the collimating lens 3 is fixed on the adjusting frame, and the position of the collimating lens 3 is adjusted in up-down, left-right, front-back, yaw angle, and pitch angle, so that the laser emitted by the semiconductor laser chip 2 can be clearly imaged in the CCD camera 7 after collimation by the collimating lens 3.

[0082] Figure 6 The light spot observed by the CCD camera during the adjustment of the collimating lens according to the embodiment of the application is shown.

[0083] The pitch angle and the yaw angle of the collimating lens 3 are finely adjusted, and the shape of the light spot imaged in the CCD camera 7 is observed, so that the position of the peak of the laser light spot 9 coincides with the position of the centroid of the laser light spot 10.

[0084] When the peak of the laser light spot 9 deviates from the centroid of the laser light spot 10 in the y direction, the pitch angle of the collimating lens 3 is adjusted; when the peak of the laser light spot 9 deviates from the centroid of the laser light spot 10 in the x direction, the yaw angle of the collimating lens 3 is adjusted, and the adjustment of the angle of the collimating lens 3 is completed.

[0085] The CCD camera 7 is moved forward and backward, the direction of the shift of the light spot on the imaging interface is observed, and the up-down and left-right positions of the collimating lens 3 are adjusted; if the light spot shifts in the y direction on the imaging interface during the movement of the CCD camera 7, the up-down position of the collimating lens 3 is adjusted; if the light spot shifts in the x direction on the imaging interface, the left-right position of the collimating lens 3 is adjusted, until the light spot is stable and does not shift any more, and the adjustment that the laser axis passes through the center of the collimating lens 3 is completed. The CCD camera 7 is continuously moved forward and backward, the shape and size of the light spot are observed, the front-back position of the collimating lens 3 is adjusted, until the size of the light spot is stable and does not change during the movement of the CCD camera 7, the adjustment that the collimating lens 3 is at the focal length of the laser is completed, and the collimation of the laser emitted by the semiconductor laser chip 2 by the collimating lens 3 is completed.

[0086] S3, a visible laser is placed on one side of the semiconductor laser chip, and the position and angle of the visible laser are adjusted, so that the visible laser emitted by the visible laser is parallel to the invisible laser.

[0087] Figure 5 The parallel alignment mode of the visible laser and the invisible laser is also shown.

[0088] Figure 7 The relative relationship between the imaging positions of the visible laser and the invisible laser on the CCD camera according to the embodiment of the application is shown.

[0089] As Figure 5 and Figure 7As shown, when the CCD camera 7 is in its initial position, the position of the laser image emitted from the semiconductor laser chip 2, collimated by the collimating lens 3, in the CCD camera 7 is recorded as coordinate A. The CCD camera 7 is then moved forward or backward a distance d, and the position of the laser image in the CCD camera 7 at this time is recorded as coordinate B.

[0090] Coarsely adjust the angle of the visible light laser 6 to be aligned with the CCD camera 7 until the laser beam is imaged in the CCD camera 7, and record the imaged spot position as A'. Move the CCD camera 7 forward or backward by the same distance d, and record the laser imaged position as B'. Adjust the yaw and pitch angles of the visible light laser 6 so that the relative coordinate relationship (slope) between coordinates A' and B' is the same as the relative coordinate relationship between coordinates A and B. This completes the parallel alignment of the two laser beams.

[0091] S4. Adjust the position and angle of the reflector so that the visible laser emitted from the adjusted visible laser is reflected along the original optical path after being incident on the reflector. Keep the angle of the reflector unchanged, adjust the position of the reflector, and move the reflector to the laser optical axis of the semiconductor laser chip.

[0092] Figure 8 The present invention illustrates an adjustment method for adjusting a reflector perpendicular to the visible laser optical axis according to an embodiment of the present invention.

[0093] like Figure 8 As shown, the position of the reflector 4 is adjusted using a visible light laser 6, which is already adjusted to be parallel to the laser emitted from the semiconductor laser chip 2, so that the laser from the visible light laser 6 illuminates the reflector 4. The laser path after reflection by the reflector 4 is observed, and the tilt and pitch angles of the reflector 4 are adjusted so that the reflected laser returns along the original incident path and illuminates the output port of the visible light laser 6. At this point, it can be determined that the reflector 4 is perpendicular to the laser axis. Then, the up / down, forward / backward, and left / right positions of the reflector 4 are adjusted so that the reflector 4 is moved back to the laser axis of the semiconductor laser chip 2 while maintaining its angle, thus completing the optical path construction of the external reflector 4 as a laser resonator.

[0094] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and modify the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0095] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

[0096] The above specific embodiments of the present application do not constitute a limitation on the scope of protection of the present application. Any various other corresponding changes and modifications made in accordance with the technical concept of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A method for optical path coupling and alignment of an external cavity semiconductor laser, wherein the external cavity semiconductor laser comprises a semiconductor laser chip, a collimating lens, and a reflecting mirror arranged sequentially, characterized in that, Includes the following steps: Adjust the position and angle of the optical fiber to couple it with the semiconductor laser chip; Adjust the position and angle of the collimating lens so that the invisible laser emitted from the semiconductor laser chip is collimated by the collimating lens; A visible light laser is placed on one side of the semiconductor laser chip. The position and angle of the visible light laser are adjusted so that the visible laser emitted by the visible light laser is parallel to the invisible laser. The specific process of adjusting the angle of the visible light laser to make the visible laser emitted by the visible light laser parallel to the invisible laser is as follows: Place the CCD camera in the initial position and record the imaging position of the invisible laser emitted by the semiconductor laser chip in the CCD camera after being collimated by the collimating lens, denoted as coordinate A; Move the CCD camera a distance d in a direction closer to or further away from the collimating lens, and record the imaging position of the invisible laser in the CCD camera at this time, denoted as coordinate B; Adjust the angle of the visible light laser so that the visible light laser emitted by the visible light laser is imaged in the CCD camera, and record the image position of the visible light laser in the CCD camera at this time, denoted as coordinate A'; Move the CCD camera a distance d in a direction closer to or further away from the collimating lens, and record the imaging position of the visible laser in the CCD camera at this time, denoted as coordinate B`. Adjust the yaw and pitch angles of the visible light laser so that the slope between coordinates A' and B' is the same as the slope between coordinates A and B; Adjust the position and angle of the reflector so that the visible laser emitted from the adjusted visible laser is incident on the reflector and reflected along the original optical path. Keep the angle of the reflector unchanged, adjust the position of the reflector, and move the reflector to the laser optical axis of the semiconductor laser chip.

2. The optical path coupling alignment method for an external cavity semiconductor laser as described in claim 1, characterized in that, The specific process of adjusting the position and angle of the optical fiber to couple it with the semiconductor laser chip is as follows: Coarse adjustment stage: Adjust the yaw angle of the optical fiber so that the direction of the optical fiber is consistent with the incident waveguide direction of the waveguide structure in the semiconductor laser chip; Adjust the pitch angle of the optical fiber so that the direction of the optical fiber is consistent with the horizontal direction of the semiconductor laser chip; Adjust the position of the optical fiber so that the tip of the optical fiber is aligned with the light inlet of the waveguide structure; Fine-tuning stage: An optical power meter is placed at the end of the semiconductor laser chip that is away from the optical fiber. Adjust the position of the optical fiber until the optical power detected by the optical power meter shows a jump increase. Stop adjusting the optical fiber and use the position of the optical fiber at this time as a reference point to fine-tune the left-right and up-down positions of the optical fiber to find the highest point of optical power in both directions. Adjust the pitch and yaw angles of the optical fiber until the optical power meter detects the maximum optical power.

3. The optical path coupling alignment method for an external cavity semiconductor laser as described in claim 1, characterized in that, The specific process of adjusting the position and angle of the collimating lens to collimate the invisible laser emitted from the semiconductor laser chip is as follows: The collimating lens is fixed on the adjustment frame, and a CCD camera is placed in the transmission direction of the collimating lens; The position and angle of the collimating lens are coarsely adjusted so that the invisible laser emitted from the semiconductor laser chip is clearly imaged in the CCD camera after passing through the collimating lens. Fine-tune the pitch and yaw angles of the collimating lens so that the peak position of the light spot coincides with the centroid position of the light spot. Then fine-tune the left-right and up-down positions of the collimating lens until the position of the light spot no longer changes when the CCD camera is moved, thus completing the adjustment of the laser optical axis passing through the center of the collimating lens. Adjust the position of the collimating lens relative to the semiconductor laser chip until the size of the light spot no longer changes when the CCD camera is moved, thus completing the adjustment of the collimating lens at the laser focal length.

4. The optical path coupling alignment method for an external cavity semiconductor laser as described in claim 1, characterized in that, The specific process of adjusting the position and angle of the reflector so that the visible light emitted by the adjusted visible light laser is reflected along the original optical path after being incident on the reflector is as follows: Adjust the position of the reflector so that the visible laser light from the adjusted visible laser shines on the reflector; Observe the reflected laser after it has been reflected by the mirror, and adjust the tilt and pitch angles of the mirror so that the reflected laser returns along the original incident light path and illuminates the output port of the visible light laser. At this time, the mirror is perpendicular to the laser optical axis of the visible light laser.

Images