A tunable semiconductor laser

Abstract

The utility model belongs to the field of semiconductor laser, disclose a kind of tunable semiconductor laser, including light source pedestal and lens pedestal, two heat sinks are installed on light source pedestal, first support and second support are equipped between two heat sinks, semiconductor laser diode is fixed on first support, aspheric lens is fixed on second support;First fixed base and second fixed base are fixed on lens pedestal, fixed reflection type blazed grating on first fixed base, fixed mirror on second fixed base;Light source pedestal and lens pedestal hinged connection, and the incidence angle θ of incident laser entering reflection type blazed grating is adjusted by adjusting unit.The utility model has adopted high ruling density grating, carries out feedback enhancement to s polarization, increases piezoelectric ceramic stack to carry out dynamic mode locking, triple improvement forms technical synergy, and the performance of semiconductor laser is overturned and broken through.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor lasers, and relates to diffraction gratings, specifically a tunable semiconductor laser. Background Technology

[0002] In the field of laser precision control, semiconductor lasers in the 630-645nm band face unique technical challenges. Lasers in this band require stringent requirements to simultaneously meet narrow linewidth, wide tuning range, and high stability for ultra-precision applications such as atomic cooling and Raman spectroscopy. However, existing technologies suffer from multiple technical bottlenecks due to limitations in red-light band material properties and conflicting device performance demands.

[0003] 1. The gain spectrum is asymmetric, which limits the tuning range.

[0004] 2. Low dispersion gratings cause a bottleneck in linewidth compression.

[0005] 3. Polarization angle mismatch causes energy loss.

[0006] 4. Lack of dynamic temperature control exacerbates wavelength instability.

[0007] These technical bottlenecks severely restrict the application of 630-645nm lasers in the field of high-precision measurement. There is an urgent need for a new semiconductor laser that can combine spectral performance, dynamic stability and grating coupling efficiency to fill the gaps in existing technologies. Utility Model Content

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a tunable semiconductor laser that overcomes the triple technical barriers of spectral performance, dynamic stability, and optomechanical coupling efficiency, thereby meeting the high-precision application requirements of reality.

[0009] To achieve the above objectives, this utility model provides the following technical solution: a tunable semiconductor laser, comprising a light source base and a lens base; Two heat sinks are installed on the light source base, and a first bracket and a second bracket are provided between the two heat sinks. A semiconductor laser diode is fixed on the first bracket, and an aspherical lens for collimating or focusing the incident laser is fixed on the second bracket. The lens base is fixed with a first fixing seat and a second fixing seat. A reflective blazed grating is fixed on the first fixing seat, and a reflector is fixed on the second fixing seat. The incident laser emitted by the semiconductor laser diode is incident on the aspherical lens, then diffracted by the reflective blazed grating, and then exited through the reflector. The light source base and the lens base are connected by a hinge, and the incident angle θ of the incident laser entering the reflective blazed grating is adjusted by an adjustment unit.

[0010] Preferably, the adjustment unit includes a piezoelectric ceramic stack, and an installation notch is reserved on one side of the light source base, into which the piezoelectric ceramic stack is installed; one end of the piezoelectric ceramic stack is hinged to the light source base via a ball joint, and the other end is hinged to the lens base via a ball joint. The light source base and the lens base are connected by a spherical fulcrum on the other side; Several springs are connected between the middle of the light source base and the lens base.

[0011] Preferably, the laser emission end face of the semiconductor laser diode is uncoated to avoid external cavity feedback interference.

[0012] Preferably, the numerical aperture NA of the aspherical lens is ≥0.5 (numerical aperture = sine of the maximum acceptable light angle × refractive index of the medium), and the surface of the aspherical lens is coated with an anti-reflection film. The aspherical lens collimates the output light of the semiconductor laser diode into an elliptical spot of 7.5mm × 2mm, ensuring that the major axis of the spot is strictly parallel to the scribe line direction of the subsequent reflective blazed grating, and that the major axis of the output light is parallel to the scribe line direction of the reflective blazed grating.

[0013] Preferably, the piezoelectric ceramic stack is used to adjust the hinge angle between the light source base and the lens base, thereby adjusting the incident angle θ of the incident laser entering the reflective blazed grating.

[0014] Preferably, the minimum adjustment angle of the incident angle θ in the positive direction is 0.5°, and similarly, the minimum adjustment angle of the incident angle θ in the negative direction is -0.5°; the angular resolution during incident angle θ adjustment is ≤0.005°. Specifically: the positive and negative directions are defined relative to the center wavelength of the emitted laser. Taking the incident angle θ at the location of the reflective blazed grating at the output center wavelength as the 0° position during adjustment, the incident angle θ can be changed on both sides (positive and negative directions) of the 0° position by adjusting the piezoelectric ceramic stack, and the wavelength of the emitted laser changes with the change of the incident angle θ.

[0015] Preferably, the reflective blazed grating has a scribe line density of 1500-2500 l / mm and a blaze wavelength of 500-750 nm.

[0016] Preferably, the incident laser enters the reflective blazed grating at an incident angle θ = 35.04°. The incident angle θ is calculated using the formula θ = arcsin(λG / 2) ± 1°, where λ is the laser wavelength and G is the grating line density. After diffraction by the reflective blazed grating, the 0th order diffracted light becomes the output beam; the +1st order diffracted light serves as the pump source and is reflected back to the emitting region of the semiconductor laser diode. Through competition within the light source, the wavelength of the laser emitted by the semiconductor laser diode again approaches the wavelength of the reflected +1st order diffracted light, effectively reducing the spectral width.

[0017] Preferably, the distance between the reflective blazed grating and the aspherical lens is 4.0 ± 0.1 cm.

[0018] The working principle of this utility model: Because of the thermal coupling between the semiconductor laser diode and the external cavity of the reflective blazed grating, when incident laser light irradiates the blazed grating, the energy carried by the incident laser affects the temperature of the blazed grating, causing thermal expansion and resulting in a change in the output wavelength, making it difficult to stably output laser light of a specific wavelength. This invention uses a temperature control loop and an angle control loop together to stabilize the laser wavelength.

[0019] Temperature control loop: The temperature of the semiconductor laser diode of the laser is detected by a temperature sensor, and the detected temperature is transmitted to the PID controller. The PID controller drives the TEC cooler to adjust the temperature of the heat sink, so that the operating temperature of the semiconductor laser diode itself is kept stable.

[0020] Angle control loop: An external vibration sensor detects environmental vibrations, and a wavelength meter connected to the reflective blazed grating measures the change in the output wavelength Δλ of the external cavity. An angle calculator combines the signals from both and outputs the signal to the microcontroller to generate a compensation voltage. This voltage controls the extension and retraction length of the piezoelectric ceramic stack, thereby changing the hinge angle between the light source base and the lens base. This allows for adjustment of the incident angle θ of the incident laser entering the reflective blazed grating in both positive and negative directions, achieving the purpose of adjusting the output wavelength of the external cavity and stabilizing the laser wavelength.

[0021] Compared with the prior art, the beneficial effects of this utility model are: This invention employs a high-density grating, feedback enhancement for s-polarization, and dynamic mode-locking with a piezoelectric ceramic stack. These three improvements work synergistically to achieve a revolutionary breakthrough in the performance of semiconductor lasers at 638nm.

[0022] This invention employs a high-dispersion grating combined with s-polarization feedback to compress the laser linewidth to 3.5 pm, meeting the requirements of ultra-precise measurement and providing the first commercially available red narrow-linewidth light source for fields such as quantum sensing.

[0023] This invention achieves asymmetric tuning by dynamically adjusting the grating angle from 34.67° to 35.32° using a piezoelectric ceramic stack, thereby increasing the coverage range of the gain spectrum. Simultaneously, a closed-loop temperature drift compensation algorithm is employed to suppress wavelength drift from ±0.1nm to ±0.01nm, solving the lock-out problem in high-precision gas detection.

[0024] This invention is simple to design and manufacture, and has a low cost. It has significant advantages in power stability, and can work continuously and stably for a long time in industrial environments of -10~40℃. It also has high working efficiency and significantly improved yield. Attached Figure Description

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0027] Figure 2 This is a schematic diagram illustrating the principle of stabilizing the laser wavelength according to this invention.

[0028] In the figure, 1-light source base, 11-mounting notch, 2-lens base, 21-first fixing seat, 22-second fixing seat, 3-heat sink, 31-first bracket, 32-second bracket, 4-semiconductor laser diode, 5-aspherical lens, 6-piezoelectric ceramic stack, 7-reflective blazed grating, 8-reflector, 9-spring, 10-spherical fulcrum. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] Example: Reference Figure 1 The tunable semiconductor laser shown includes a light source base 1 and a lens base 2. Two heat sinks 3 are mounted on the light source base 1, and a first bracket 31 and a second bracket 32 ​​are provided between the two heat sinks 3. A semiconductor laser diode 4 is fixed on the first bracket 31, and an aspherical lens 5 for collimating or focusing the incident laser is fixed on the second bracket 32. A first fixing seat 21 and a second fixing seat 22 are fixed on the lens base 2. A reflective blazed grating 7 is fixed on the first fixing seat 21, and a reflector 8 is fixed on the second fixing seat 22. The two fixing seats work together to ensure the accuracy of the optical path and avoid optical path disorder caused by lens misalignment.

[0031] The incident laser emitted by the semiconductor laser diode 4 is incident on the aspherical lens 5, then diffracted by the reflective blazed grating 7, and exits through the reflecting mirror 8. The reflecting mirror 8 changes the propagation direction of the laser through mirror reflection. Figure 1 The middle arrow indicates that the laser is reflected and output in a specific direction. The distance between the reflective blazed grating 7 and the aspherical lens 5 is 4.0 ± 0.1 cm.

[0032] The light source base 1 and lens base 2 are connected by a hinge, and the incident angle of the incident laser entering the reflective blazed grating 7 is adjusted by an adjustment unit. The adjustment unit includes a piezoelectric ceramic stack 6. A mounting notch 11 is provided on one side of the light source base 1, and the piezoelectric ceramic stack 6 is installed within the mounting notch 11. One end of the piezoelectric ceramic stack 6 is hinged to the light source base 1 via a ball joint, and the other end is hinged to the lens base 2 via a ball joint. The other sides of the light source base 1 and lens base 2 are connected by a spherical fulcrum 10. Three sets of springs 9 are connected between the middle of the light source base 1 and lens base 2. The two bases jointly support and fix other components, ensuring the stability of the overall structure. The springs 9 provide elastic connection while also acting as a buffer, allowing the two bases to adjust their displacement within a certain range.

[0033] Preferably, the heat sink 3 is equipped with a cooler to achieve precise temperature control of ±0.1℃; it provides heat dissipation for the semiconductor laser diode 7, which can accurately ensure its stable operating temperature and avoid affecting the laser emission performance due to overheating.

[0034] Preferably, the semiconductor laser diode 4 has a wavelength range of 630-645nm, a center wavelength of 638nm, and outputs s-polarized AlGaInP red light, which is responsible for generating the initial laser beam. The laser emission end face of the semiconductor laser diode 4 is uncoated to avoid external cavity feedback interference.

[0035] Preferably, the aspherical lens 5 has a focal length of 4.02 mm, a numerical aperture NA of 0.6, and is coated with a 638 nm anti-reflection film with a reflectivity of <0.2%, adapting to the elliptical spot of the laser. The aspherical lens 5 can collimate the output light of the semiconductor laser diode 4 into an elliptical spot of 7.5 mm × 2 mm, ensuring that the long axis of the spot is strictly parallel to the scribe line direction of the subsequent reflective blazed grating 7, and that the long axis of the output light is parallel to the scribe line direction of the reflective blazed grating 7, thus optimizing the beam quality.

[0036] Preferably, the piezoelectric ceramic stack 6 utilizes the piezoelectric effect to change its length, adjusting the hinge angle between the light source base 1 and the lens base 2, thereby adjusting the incident angle θ of the incident laser entering the reflective blazed grating 7. The minimum adjustment angle of the incident angle θ in the positive direction is 0.5°, and similarly, the minimum adjustment angle of the incident angle θ in the negative direction is -0.5°; the angular resolution during the adjustment of the incident angle θ is ≤0.005°, and the voltage-angle conversion coefficient K=0.03-0.07° / V. The function of the piezoelectric ceramic stack 6 is to precisely control the optical path and, in conjunction with the reflective blazed grating 7, to perform wavelength selection.

[0037] Specifically, the positive and negative directions are defined relative to the center wavelength of the emitted laser. The incident angle θ at the position of the reflective blazed grating 7 when the output center wavelength is used as the 0° position for adjustment. By adjusting the piezoelectric ceramic stack 6, the angle of incident angle θ can be changed on both sides (positive and negative directions) of the 0° position. The wavelength of the emitted laser changes with the change of the incident angle θ.

[0038] The maximum variation in the length of the piezoelectric ceramic stack 6 of this invention is 0.23 mm, with an adjustment resolution of 0.35 μm. This value is calculated based on the angle adjustment requirements. In practice, the length adjustment of the piezoelectric ceramic stack 6 is determined based on the relationship between the angle and the applied voltage. Precise adjustment of the incident angle θ optimizes the output wavelength and meets the requirements for ultra-fine measurement.

[0039] Preferably, the reflective blazed grating 7 has a scribe line density of 1500-2500 l / mm and a blaze wavelength of 500-750 nm, which splits or modulates the laser through diffraction (such as selecting a specific wavelength or changing the direction of beam propagation).

[0040] Preferably, the incident laser enters the reflective blazed grating 7 at an incident angle θ = 35.04°. The incident angle θ is calculated using the formula θ = arcsin(λG / 2) ± 1°, where λ is the laser wavelength and G is the grating line density. After diffraction by the reflective blazed grating, the 0th order diffracted light becomes the output beam; the +1st order diffracted light serves as the pump source and is reflected back to the emitting region of the semiconductor laser diode. Through competition within the light source, the wavelength of the laser emitted by the semiconductor laser diode again approaches the wavelength of the reflected +1st order diffracted light, effectively reducing the spectral width.

[0041] like Figure 2 As shown, the principle of this invention for stabilizing laser wavelength is as follows: Because of the thermal coupling between the semiconductor laser diode 4 and the outer cavity of the reflective blazed grating 7, when the incident laser irradiates the reflective blazed grating 7, the energy carried by the incident laser will affect the temperature of the reflective blazed grating 7, causing thermal expansion of the reflective blazed grating 7 and resulting in a change in the output wavelength, making it difficult to stably output laser of a specific wavelength. This invention uses a temperature control loop and an angle control loop (dual control loops) to stabilize the laser wavelength.

[0042] Temperature control loop: The temperature of the semiconductor laser diode 4 of the laser is detected by a temperature sensor and transmitted to the PID controller. The PID controller drives the TEC cooler to adjust the temperature of the heat sink 3, so that the operating temperature of the semiconductor laser diode 4 is kept stable.

[0043] Angle control loop: An external vibration sensor detects environmental vibrations, and a wavelength meter connected to the reflective blazed grating 7 measures the change in the output wavelength Δλ of the external cavity. An angle calculator combines the two signals and outputs the signal to the microcontroller to generate a compensation voltage. This voltage controls the extension and retraction length of the piezoelectric ceramic stack 6, thereby changing the hinge angle between the light source base 1 and the lens base 2. This allows for adjustment of the incident angle θ of the incident laser entering the reflective blazed grating in both positive and negative directions, achieving the purpose of adjusting the output wavelength of the external cavity and stabilizing the laser wavelength.

[0044] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A tunable semiconductor laser, characterized in that, Includes a light source base (1) and a lens base (2); Two heat sinks (3) are installed on the light source base (1). A first bracket (31) and a second bracket (32) are provided between the two heat sinks (3). A semiconductor laser diode (4) is fixed on the first bracket (31), and an aspherical lens (5) for collimating or focusing the incident laser is fixed on the second bracket (32). The lens base (2) is fixed with a first fixing seat (21) and a second fixing seat (22). The first fixing seat (21) is fixed with a reflective blazed grating (7), and the second fixing seat (22) is fixed with a reflector (8). The incident laser emitted by the semiconductor laser diode (4) is incident on the aspherical lens (5), then diffracted by the reflective blazed grating (7), and then emitted through the reflector (8); The light source base (1) and the lens base (2) are connected by a hinge, and the incident angle θ of the incident laser entering the reflective blazed grating (7) is adjusted by the adjustment unit.

2. The tunable semiconductor laser according to claim 1, characterized in that: The adjustment unit includes a piezoelectric ceramic stack (6), and an installation notch (11) is reserved on one side of the light source base (1). The piezoelectric ceramic stack (6) is installed in the installation notch (11). One end of the piezoelectric ceramic stack (6) is hinged to the light source base (1) by ball joint, and the other end is hinged to the lens base (2) by ball joint. The light source base (1) and the lens base (2) are connected by a spherical fulcrum (10) on the other side; Several springs (9) are connected between the middle of the light source base (1) and the lens base (2).

3. The tunable semiconductor laser according to claim 1, characterized in that: The laser emission end face of the semiconductor laser diode (4) is uncoated.

4. The tunable semiconductor laser according to claim 3, characterized in that: The numerical aperture NA of the aspherical lens (5) is ≥0.5, and the surface of the aspherical lens (5) is coated with an anti-reflection film.

5. The tunable semiconductor laser according to claim 2, characterized in that: The piezoelectric ceramic stack (6) is used to adjust the hinge angle between the light source base (1) and the lens base (2), thereby adjusting the incident angle θ of the incident laser entering the reflective blazed grating (7).

6. The tunable semiconductor laser according to claim 5, characterized in that: The minimum adjustment angle of the incident angle θ along the positive direction is 0.5°, and similarly, the minimum adjustment angle of the incident angle θ along the negative direction is -0.5°; the angular resolution when adjusting the incident angle θ is ≤0.005°.

7. The tunable semiconductor laser according to claim 6, characterized in that: The reflective blazed grating (7) has a scribe line density of 1500-2500 l / mm and a blaze wavelength of 500-750 nm.

8. The tunable semiconductor laser according to claim 7, characterized in that: The incident laser enters the reflective blazed grating (7) at an incident angle θ = 35.04°.

9. The tunable semiconductor laser according to claim 7 or 8, characterized in that: The distance between the reflective blazed grating (7) and the aspherical lens (5) is 4.0 ± 0.1 cm.

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