Wavelength-locked semiconductor laser

Abstract

The invention discloses a wavelength-locked semiconductor laser, which comprises a semiconductor laser chip, a collimating lens, a re-collimating lens, a sampling reflector and a wavelength locking module, and is characterized in that the collimating lens and the re-collimating lens are sequentially arranged along the laser beam emitting direction of the semiconductor laser chip; the sampling reflector is used for sampling the light spot edge of the laser beam passing through the re-collimating lens and reflecting the light spot edge to the wavelength locking module, and a feedback beam sequentially passes through the sampling reflector, the focus of the re-collimating lens, the re-collimating lens and the collimating lens and then returns to the semiconductor laser chip. According to the wavelength locking semiconductor laser, the power density of the wavelength locking module can be greatly reduced, and the temperature characteristic of the wavelength locking module is improved; a non-luminous area at the edge of the semiconductor laser chip is prevented from absorbing feedback beams, cavity surface temperature is reduced, and the service life and reliability of the laser are greatly improved; the laser output beam quality is improved, and the stability and reliability of the semiconductor laser are improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a wavelength-locked semiconductor laser. Background Art

[0002] High-power gas lasers have high power and good beam quality and are widely used in different fields. Since the absorption peak of gas lasers is narrow, the absorption zone width (FWHM) is usually much less than 1nm. It is necessary to wavelength lock the semiconductor laser diode to stabilize the output center wavelength while narrowing the output spectrum width. Otherwise, the pump light absorption efficiency is low and the energy loss is serious. The unabsorbed energy will be reflected multiple times inside the laser, causing the laser temperature to rise or even burn out the laser.

[0003] Conventional external cavity wavelength locking structures require a volume Bragg grating (VBG) to be placed inside the pump source, or a volume grating to be placed at the front end of each chip. The locking effect of the volume grating, that is, the center wavelength of the spectrum after locking, varies with the laser operating current and laser temperature (the amount of change is about 0.03nm / ℃). In some fields that require the output center wavelength to be stable, such as pumping alkali metal gas lasers, the temperature of the volume grating needs to be actively controlled due to the narrow absorption peak (FWHM is approximately 0.3nm). Therefore, if a high-power narrow-linewidth wavelength-locked semiconductor laser using a volume grating needs to accurately control the output wavelength and spectral width, the volume grating needs to be precisely temperature-controlled, and the difficulty of control increases with the number of pump sources. Summary of the invention

[0004] In order to solve one or more of the above problems, the present application proposes a wavelength-locked semiconductor laser.

[0005] According to one aspect of the present application, a wavelength-locked semiconductor laser is provided, comprising a semiconductor laser chip, a collimating lens, a re-collimating lens, a sampling reflector and a wavelength locking module. The collimating lens and the re-collimating lens are sequentially arranged along the laser beam emission direction of the semiconductor laser chip. The sampling reflector is arranged on a side of the re-collimating lens away from the collimating lens. The sampling reflector is used to sample the edge of the spot of the laser beam after passing through the re-collimating lens. The sampling reflector can collect a preset proportion of the laser beam and reflect the collected sampling beam to the wavelength locking module. The wavelength locking module is used to perform wavelength selection on the incident sampling beam and feed back a beam of a specific wavelength. The feedback beam emitted by the wavelength locking module passes through the sampling reflector, the focus of the re-collimating lens, the re-collimating lens and the collimating lens in sequence and then returns to the semiconductor laser chip.

[0006] In some embodiments, the collimating lens is a circular lens, the light emitting cavity surface of the semiconductor laser chip is arranged on the focal plane of the collimating lens, and the collimating lens is used to collimate the laser beam in the fast axis direction and expand the divergence angle in the slow axis direction; or, The collimating lens includes a first cylindrical lens and a second cylindrical lens, which are sequentially arranged along the light emitting direction of the semiconductor laser chip. The first cylindrical lens is used to collimate the laser beam in the fast axis direction, and the second cylindrical lens is used to expand the divergence angle of the laser beam in the slow axis direction.

[0007] In some embodiments, the focal length of the collimating lens is no greater than half of the Rayleigh interval in the slow axis direction of the light output from the semiconductor laser chip.

[0008] In some embodiments, the collimating lens is a cylindrical lens, and the Rayleigh interval of the laser beam in the slow axis direction after passing through the collimating lens is recorded as Z R1 , and then the focal length of the collimating lens is n times Z R1 , n is an integer not less than 20.

[0009] In some embodiments, the distance between the collimating lens and the re-collimating lens is the sum of the focal length of the collimating lens and the focal length of the re-collimating lens.

[0010] In some embodiments, the horizontal distance between the center of the sampling reflector and the plane where the re-collimating lens is located is not less than twice the focal length of the re-collimating lens, and is not greater than one quarter of the Rayleigh interval in the slow axis direction of the laser beam after passing through the re-collimating lens.

[0011] In some embodiments, the proportion of the laser beam collected by the sampling mirror is 5%-50%.

[0012] In some embodiments, the wavelength locking module is a volume grating or a reflective surface grating or a transmissive surface grating and a reflector disposed behind the transmissive surface grating.

[0013] In some embodiments, assuming that there is a virtual wavelength locking module, the virtual wavelength locking module and the wavelength locking module are symmetrical about the sampling reflector axis, assuming that the angle between the sampling beam incident on the wavelength locking module and the sampling beam emitted from the wavelength locking module is θ, the angle between the sampling reflector and the optical axis is β, and the angle between the straight line where the incident surface of the virtual wavelength locking module is located and the straight line where the incident surface of the wavelength locking module is located is α, then β=90-α / 2-θ / 2.

[0014] In some embodiments, there is a virtual incident point on the virtual wavelength locking module, and the virtual incident point is symmetrical with the incident point of the sampling beam on the wavelength locking module about the sampling reflector axis. The expression of the angle θ between the sampling beam incident on the wavelength locking module and the sampling beam emitted from the wavelength locking module is as follows:

[0015] Wherein, f1 represents the focal length of the collimating lens, f2 represents the focal length of the re-collimating lens, w0 represents the spot width in the slow axis direction of the laser beam emitted by the semiconductor laser chip, L1 represents the horizontal distance between the incident point of the sampling beam on the sampling reflector and the re-collimating lens, and L2 represents the horizontal distance between the incident point of the sampling beam on the sampling reflector and the virtual incident point on the virtual wavelength locking module.

[0016] The present application discloses a wavelength-locked semiconductor laser. The edge spot of the semiconductor laser chip output cavity surface is expanded by an optical element, and then the edge spot is sampled, so that the low-power spot at the edge of the laser beam is incident on the wavelength locking module for wavelength selection, which can greatly reduce the power density on the wavelength locking module, improve the temperature characteristics of the wavelength locking module, and reduce the drift of the semiconductor laser wavelength over time and the temperature gradient inside the wavelength locking module without active temperature control; the edge beam after wavelength selection is fed back to the center of the semiconductor laser chip cavity surface, so as to avoid the semiconductor laser chip edge non-luminous area absorbing the feedback beam, reduce the cavity surface temperature, and greatly improve the laser life and reliability; sampling is performed at the edge of the spot, so as to reduce the output beam size and improve the laser output beam quality. Since the size of the semiconductor laser chip output cavity surface spot is controlled by a waveguide, the waveguide size will not change with the operating temperature and the operating current. Therefore, after the sampling ratio is determined, the sampled spot size will not change with the temperature and the current, so as to improve the stability and reliability of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A top view of a wavelength-locked semiconductor laser provided in one embodiment of the present application.

[0018] Figure 2 A light path diagram of a laser beam passing through a collimating lens in a wavelength-locked semiconductor laser provided in one embodiment of the present application when the collimating lens is a circular lens.

[0019] Figure 3 A light path diagram of a laser beam passing through a collimating lens in a wavelength-locked semiconductor laser provided in one embodiment of the present application when the collimating lens is two cylindrical lenses.

[0020] Figure 4 An optical path diagram of a wavelength-locked semiconductor laser provided in one embodiment of the present application.

[0021] Figure 5 A top view of another wavelength-locked semiconductor laser provided in an embodiment of the present application.

[0022] Figure 6 A top view of another wavelength-locked semiconductor laser provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are part of the embodiments of the present application, rather than all of the embodiments, and are only used to explain the present application, and are not used to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0024] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "two ends", "both sides", "bottom", "top" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred elements must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present application. In addition, the terms "first", "second", "superior", "inferior", "primary", "secondary" and the like are only used for descriptive purposes and can be simply used to more clearly distinguish different components, but cannot be understood as indicating or implying relative importance.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] Example: Reference Manual Attached Figure 1 An embodiment of the present application provides a wavelength-locked semiconductor laser, including a semiconductor laser chip 1, a collimating lens 2, a re-collimating lens 3, a sampling reflector 4 and a wavelength locking module 5.

[0028] Wherein, a collimating lens 2 and a re-collimating lens 3 are sequentially arranged along the laser beam emission direction of the semiconductor laser chip 1 .

[0029] The sampling reflector 4 is arranged on the side of the re-collimating lens 3 away from the collimating lens 2. The sampling reflector 4 is used to sample the edge of the spot of the laser light beam after passing through the re-collimating lens. The sampling reflector 4 can collect a preset proportion of the laser light beam. A part of the laser light beam passing through the re-collimating lens 3 is incident on the sampling reflector 4, and after being reflected by the sampling reflector 4, it is incident on the wavelength locking module 5 as a sampling light beam, and the direction of the other part of the laser light beam remains unchanged.

[0030] The wavelength locking module 5 is used to select the wavelength and feed back a light beam of a specific wavelength. The sampling light beam incident on the wavelength locking module 5 emits a feedback light beam of a specific wavelength after the wavelength is locked by the wavelength locking module 5. The feedback light beam passes through the sampling reflector 4, the focus of the re-collimating lens 3, the re-collimating lens 3 and the collimating lens 2 in sequence and then returns to the center of the semiconductor laser chip.

[0031] The collimating lens 2 is a positive lens, that is, a lens with a positive focal length.

[0032] In an optional embodiment, the collimating lens 2 can be a circular lens, and the light emitting cavity surface of the semiconductor laser chip 1 is arranged on the focal plane of the collimating lens 2. The collimating lens 2 is used to collimate the laser beam emitted by the semiconductor laser chip 1 in the fast axis direction and expand the divergence angle in the slow axis direction. Figure 2 , Instructions attached Figure 2 The figure shows the optical path diagram of the laser beam when it passes through the collimating lens 2 when the collimating lens 2 is a circular lens, wherein (a) is a top view and (b) is a side view.

[0033] In an optional embodiment, the collimating lens 2 may be two cylindrical lenses. The collimating lens 2 may include a first cylindrical lens 21 and a second cylindrical lens 22. The first cylindrical lens 21 and the second cylindrical lens 22 are sequentially arranged along the light emitting direction of the semiconductor laser chip 1. The first cylindrical lens 21 is used to collimate the laser beam in the fast axis direction, and the second cylindrical lens 22 is used to expand the divergence angle in the slow axis direction of the laser beam. Figure 3 , Instructions attached Figure 3 The figure shows the optical path diagram of the laser beam when it passes through the collimating lens 2 when the collimating lens 2 is two cylindrical lenses, wherein (a) is a top view and (b) is a side view.

[0034] When the divergence angle of the laser beam after passing through the collimating lens 2 is greater than the divergence angle of the laser beam before entering the collimating lens 2, that is, the focal length of the collimating lens 2 is not greater than half of the Rayleigh interval length in the slow axis direction of the laser beam output by the semiconductor laser chip 1. When the collimating lens 2 is two cylindrical lenses, the focal length of the second cylindrical lens 22 is not greater than half of the Rayleigh interval length in the slow axis direction of the laser beam output by the laser chip.

[0035] The length of the Rayleigh interval is denoted as Z R , Z R =w1 / θ1, where w1 represents the spot width and the intensity becomes 1 / e of the peak intensity. 2 When the spot width is half, θ1 represents the spot divergence angle, and the intensity becomes 1 / e of the peak intensity. 2 The corresponding spot divergence angle is half.

[0036] In this embodiment, taking the laser beam emitted by the semiconductor laser chip 1 with a slow axis w1=100μm and θ1=5° as an example, the Rayleigh interval length is 1.1mm, that is, the focal length of the collimating lens 2 is not greater than 0.55mm. Assuming the focal length of the collimating lens 2 is f1, the Rayleigh interval length after passing through the collimating lens 2 is .

[0037] In this embodiment, the fast axis w1=1μm, θ1=28°, and the slow axis w1=100μm, θ1=5° of the laser beam emitted by the semiconductor laser chip 1 are set. When the collimating lens 2 is a single circular lens with a focal length of 0.5mm, in the laser beam emitted by the semiconductor laser chip 1, after the fast axis beam passes through the collimating lens 2, θ1 decreases from 28° to 0.1°, and the Rayleigh interval length of the fast axis beam changes from 1.6μm to 152.7mm; after the slow axis beam passes through the collimating lens 2, θ1 expands from 5° to 11.5°, and the Rayleigh interval length of the slow axis beam changes from 1.1mm to 0.2mm, the spot size changes, and the slow axis spot image is formed from 2mm to infinity from the light emitting cavity surface of the semiconductor laser chip 1, and the size of the image is proportional to the distance.

[0038] When the transmission distance of the laser beam after passing through the collimating lens 2 is much greater than the Rayleigh interval length, the distribution of the laser beam passing through the collimating lens 2 in the slow axis direction is consistent with the distribution of the laser beam emitted by the semiconductor laser chip 1 in the slow axis direction.

[0039] In an optional embodiment, the collimating lens 3 is a cylindrical lens, and the Rayleigh interval of the laser beam in the slow axis direction after passing through the collimating lens 2 is recorded as Z R1 , then the focal length of the collimating lens is n times Z R1 , n is an integer not less than 20. And the distance between the collimating lens 2 and the re-collimating lens 3 is the sum of the focal length of the collimating lens 2 and the focal length of the re-collimating lens 3 .

[0040] In this embodiment, n is 50, and the focal length of the re-collimating lens 3 is set to 10 mm. The slow axis Rayleigh interval length of the laser beam after passing through the re-collimating lens 3 is 458.4 mm, and the spot size remains approximately unchanged within a length range of 100 mm after passing through the re-collimating lens 3.

[0041] The horizontal distance between the center of the sampling reflector 4 and the plane where the re-collimating lens 3 is located is not less than twice the focal length of the re-collimating lens 3 , and is not greater than one quarter of the Rayleigh interval in the slow axis direction of the laser beam after passing through the re-collimating lens 3 .

[0042] This is because the spot size remains approximately unchanged within the 1 / 4 length of the slow axis Rayleigh interval in the slow axis direction of the laser beam after passing through the re-collimating lens 3. Therefore, the sampling reflector 4 can collect the edge beam of the laser beam for wavelength locking. Moreover, since the spot size remains unchanged within this range, the sampling ratio can also remain unchanged after the sampling reflector 4 is fixed.

[0043] Therefore, by setting the collimating lens 2 and the re-collimating lens 3, it is possible to avoid the situation where the divergence angle of the light beam in the slow axis direction of the semiconductor laser chip 1 changes with the operating temperature and current, resulting in the inability to sample or over-sampling. Since the divergence angle of the light beam in the slow axis direction of the semiconductor laser chip 1 changes with the operating temperature and current, if the collimating lens 2 and the re-collimating lens 3 are not set, the divergence angle will decrease under low current or low temperature conditions, resulting in no light beam incident on the sampling reflector 4, and sampling and wavelength locking cannot be performed. Under high current or high temperature conditions, the divergence angle of the semiconductor laser chip 1 increases, resulting in the light beam incident on the sampling reflector 4 being too large, over-sampling, and damaging the chip. Moreover, there is no corresponding relationship between the light beam incident on the sampling reflector 4 and the laser beam emitted by the laser chip. The feedback beam will cover the entire light-emitting cavity surface of the semiconductor laser chip, and the edge part will be absorbed, increasing the failure risk of the semiconductor laser chip 1.

[0044] The sampling reflector 4 is partially arranged on the optical path of the laser beam, that is, the sampling reflector 4 is arranged on the edge of the spot of the laser beam after passing through the re-collimating lens 3. According to different proportions of the laser beam collected by the set sampling reflector, the area where the sampling reflector 4 overlaps with the spot of the laser beam after passing through the re-collimating lens 3 is different. The larger the proportion of the laser beam collected by the sampling reflector 4, the larger the area where the sampling reflector 4 overlaps with the spot of the laser beam after passing through the re-collimating lens 3.

[0045] In an optional embodiment, a total reflection mirror is used as the sampling reflector 4. The proportion of the laser beam collected by the sampling reflector 4 can be set to 5%-50%.

[0046] Since the light-emitting cavity surface of the semiconductor laser chip 1 is located at the focal plane of the collimating lens 2, and the focal length of the collimating lens 2 is less than the Rayleigh interval length of the laser beam emitted by the semiconductor laser chip 1, the laser beam emitted by the semiconductor laser chip 1 is approximately parallel light and parallel to the optical axis. Therefore, it is assumed that a laser beam is emitted from the edge of the semiconductor laser chip 1. Since the laser beam is parallel to the optical axis, the laser beam passes through the focus of the collimating lens 2 close to the re-collimating lens 3, and then passes through the re-collimating lens 3 to be parallel to the optical axis again. The laser beam parallel to the optical axis is sampled by the sampling reflector 4, and the wavelength is selected in the wavelength locking module 5. The feedback beam emitted from the wavelength locking module 5 passes through the sampling reflector 4, the focus of the re-collimating lens 3, and the re-collimating lens 3 in sequence. The feedback beam after passing through the re-collimating lens 3 is parallel to the optical axis, and then passes through the collimating lens 2 and is incident on the center of the light-emitting cavity surface of the semiconductor laser chip 1. When the feedback beam is emitted from the wavelength locking module 5, the center of the feedback beam passes through the focus of the re-collimating lens 3.

[0047] Therefore, by setting the sampling reflector 4, it is possible to prevent the wavelength locking module 5 from directly contacting the high-power laser beam, and to prevent the gap or low-quality coating at the edge of the wavelength locking module 5 from increasing laser absorption and causing the central wavelength to change.

[0048] Assume that there is a virtual wavelength locking module 6, and the virtual wavelength locking module 6 satisfies the following conditions: when there is no sampling reflector 4, the light emitted from the edge of the semiconductor laser chip 1 can be incident on the virtual wavelength locking module 6 after passing through the collimating lens 2, the focus of the collimating lens 2 and the re-collimating lens 3 in sequence, and the feedback light emitted by the virtual wavelength locking module 6 can pass through the focus of the re-collimating lens 3, the re-collimating lens 3 and the collimating lens 2 in sequence and return to the center of the light-emitting cavity surface of the semiconductor laser chip 1.

[0049] Reference Manual Attached Figure 4 The virtual wavelength locking module 6 is symmetrical with the wavelength locking module 5 about the sampling reflector 4 axis. There is a virtual incident point on the virtual wavelength locking module 6. The virtual incident point is symmetrical with the incident point of the sampling beam on the wavelength locking module 5 about the sampling reflector 4 axis.

[0050] Assume that the angle between the sampling beam incident on the wavelength locking module 5 and the sampling beam emitted from the wavelength locking module 5 is θ, θ is also the angle between the sampling beam incident on the virtual wavelength locking module 6 and the sampling beam emitted from the virtual wavelength locking module 6, the angle between the sampling reflector 4 and the optical axis 7 is β, the angle between the straight line where the incident surface of the virtual wavelength locking module 6 is located and the straight line where the incident surface of the wavelength locking module 5 is located is α, then β=90-α / 2-θ / 2.

[0051] The expression of the angle θ between the sampling light beam incident on the wavelength locking module 5 and the sampling light beam emitted from the wavelength locking module 5 is as follows:

[0052] Wherein, f1 represents the focal length of the collimating lens 2, f2 represents the focal length of the re-collimating lens 3, w0 represents the spot width in the slow axis direction of the laser beam emitted by the semiconductor laser chip 1, L1 represents the horizontal distance between the incident point of the sampling beam on the sampling reflector 4 and the re-collimating lens 3, and L2 represents the horizontal distance between the incident point of the sampling beam on the sampling reflector 4 and the virtual incident point on the virtual wavelength locking module 6.

[0053] In an optional embodiment, the wavelength locking module 5 may use a volume grating, or a reflective surface grating 51 , or a transmissive surface grating 52 and a reflector 53 disposed behind the transmissive surface grating 52 .

[0054] Reference Manual Attached Figure 1 The wavelength locking module 5 uses a volume grating, and the reflectivity of the volume grating is 50%-100%.

[0055] Reference Manual Attached Figure 5 The wavelength locking module 5 uses a reflective surface grating 51.

[0056] Reference Manual Attached Figure 6 The wavelength locking module 5 includes a transmission surface grating 52 and a reflector 53 arranged behind the transmission surface grating 52. The sampling beam is incident on the transmission surface grating 52, and is incident on the reflector 53 after diffraction. The feedback beam emitted from the reflector 53 passes through the transmission surface grating 52 and then is emitted. The feedback beam emitted from the transmission surface grating 52 forms an angle with the sampling beam incident on the transmission surface grating 52 from the sampling reflector 4.

[0057] The feedback light beam passes through the sampling reflector 4, the re-collimating lens 3 and the collimating lens 2 in sequence, and then is incident on the central area of ​​the light-emitting cavity surface of the semiconductor laser chip 1. The area of ​​the central area of ​​the light-emitting cavity surface of the semiconductor laser chip 1 does not exceed 1 / 2 of the total area of ​​the light-emitting cavity surface, and the center position of the central area of ​​the light-emitting cavity surface of the semiconductor laser chip 1 coincides with the center position of the light-emitting cavity surface.

[0058] The present application discloses a wavelength-locked semiconductor laser. Through the arrangement of optical elements, the edge spot of the semiconductor laser chip output cavity surface is expanded and then sampled, so that the low-power spot at the edge of the laser beam is incident on the wavelength locking module for wavelength selection, which can greatly reduce the power density on the wavelength locking module, improve the temperature characteristics of the wavelength locking module, and reduce the drift of the semiconductor laser wavelength over time and the temperature gradient inside the wavelength locking module without active temperature control; the edge beam after wavelength selection is fed back to the center of the semiconductor laser chip cavity surface to avoid the semiconductor laser chip edge non-luminous area absorbing the feedback beam, reduce the cavity surface temperature, and greatly improve the laser life and reliability; sampling is performed at the edge of the spot, reducing the output beam size and improving the laser output beam quality. Since the semiconductor laser chip output cavity surface spot size is controlled by a waveguide, the waveguide size will not change with the operating temperature and the operating current. Therefore, after the sampling ratio is determined, the sampled spot size will not change with the temperature and the current, thereby improving the stability and reliability of the semiconductor laser. The above is only an optional implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A wavelength-locked semiconductor laser, characterized in that: It includes semiconductor laser chip, collimating lens, re-collimating lens, sampling reflector and wavelength locking module. The collimating lens and the re-collimating lens are sequentially arranged along the laser beam emission direction of the semiconductor laser chip, The sampling reflector is arranged on a side of the re-collimating lens away from the collimating lens, and is used to sample the edge of the spot of the laser beam after passing through the re-collimating lens. The sampling reflector can collect a preset proportion of the laser beam and reflect the collected sampling beam to the wavelength locking module. The wavelength locking module is used to select the wavelength of the incident sampling light beam and feed back a light beam of a specific wavelength. The feedback light beam emitted by the wavelength locking module passes through the sampling reflector, the focus of the re-collimating lens, the re-collimating lens and the collimating lens in sequence and then returns to the semiconductor laser chip. The wavelength locking module is a volume grating or a reflective surface grating or a transmissive surface grating and a reflector arranged behind the transmissive surface grating.

2. A wavelength-locked semiconductor laser according to claim 1, characterized in that: The collimating lens is a circular lens, the light emitting cavity surface of the semiconductor laser chip is arranged on the focal plane of the collimating lens, and the collimating lens is used to collimate the laser beam in the fast axis direction and expand the divergence angle in the slow axis direction; or, The collimating lens includes a first cylindrical lens and a second cylindrical lens, which are sequentially arranged along the light emitting direction of the semiconductor laser chip. The first cylindrical lens is used to collimate the laser beam in the fast axis direction, and the second cylindrical lens is used to expand the divergence angle of the laser beam in the slow axis direction.

3. A wavelength-locked semiconductor laser according to claim 1, characterized in that: The focal length of the collimating lens is not greater than half of the Rayleigh interval in the slow axis direction of the output light of the semiconductor laser chip.

4. The wavelength-locked semiconductor laser according to claim 1, characterized in that: The re-collimating lens is a cylindrical lens, and the Rayleigh interval of the laser beam in the slow axis direction after passing through the collimating lens is recorded as Z R1 , the focal length of the re-collimating lens is n times Z R1 , n is an integer not less than 20.

5. The wavelength-locked semiconductor laser according to claim 1, characterized in that: The distance between the collimating lens and the re-collimating lens is the sum of the focal length of the collimating lens and the focal length of the re-collimating lens.

6. The wavelength-locked semiconductor laser according to claim 1, characterized in that: The horizontal distance between the center of the sampling reflector and the plane where the re-collimating lens is located is not less than twice the focal length of the re-collimating lens, and is not greater than one quarter of the Rayleigh interval in the slow axis direction of the laser beam after passing through the re-collimating lens.

7. The wavelength-locked semiconductor laser according to claim 1, characterized in that: The proportion of the laser beam collected by the sampling reflector is 5%-50%.

8. The wavelength-locked semiconductor laser according to claim 1, characterized in that: Assume that there is a virtual wavelength locking module, and the virtual wavelength locking module is symmetrical with the wavelength locking module about the sampling reflector axis. Assume that the angle between the sampling beam incident on the wavelength locking module and the sampling beam emitted from the wavelength locking module is θ, the angle between the sampling reflector and the optical axis is β, and the angle between the straight line where the incident surface of the virtual wavelength locking module is located and the straight line where the incident surface of the wavelength locking module is located is α, then β=90-α / 2-θ / 2.

9. The wavelength-locked semiconductor laser according to claim 8, characterized in that: There is a virtual incident point on the virtual wavelength locking module, and the virtual incident point and the incident point of the sampling beam on the wavelength locking module are symmetrical about the sampling reflector axis. The expression of the angle θ between the sampling beam incident on the wavelength locking module and the sampling beam emitted from the wavelength locking module is as follows: Wherein, f1 represents the focal length of the collimating lens, f2 represents the focal length of the re-collimating lens, w0 represents the spot width in the slow axis direction of the laser beam emitted by the semiconductor laser chip, L1 represents the horizontal distance between the incident point of the sampling beam on the sampling reflector and the re-collimating lens, and L2 represents the horizontal distance between the incident point of the sampling beam on the sampling reflector and the virtual incident point on the virtual wavelength locking module.

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