Cat eye type external cavity semiconductor laser and use method thereof

Abstract

The invention relates to the technical field of semiconductor lasers, in particular to a cat eye type external cavity semiconductor laser and a using method thereof. The laser comprises a shell and a semiconductor cooler arranged at the bottom of the shell, and the semiconductor cooler is used for controlling the temperature of the laser so as to ensure the stability of the output wavelength and power of the laser; a cat eye assembly and a light filtering assembly are arranged in the shell, the light filtering assembly is used for selecting the laser with the target wavelength, and the cat eye assembly is used for reflecting the laser with the target wavelength to the laser tube; a laser tube is arranged at the tail end of the shell, an outer cavity is formed between a laser emergent surface of the laser tube and a light splitting surface of the cat eye assembly, and the outer cavity is formed in the shell, so that the cat eye assembly, the laser tube, the light filtering assembly, the outer cavity and the shell form an integrated structure. The anti-vibration stability of the laser is optimized through the integrated design, and the temperature drift resistance of the laser is improved through the semiconductor cooler arranged at the bottom of the shell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor lasers, in particular to a cat-eye external cavity semiconductor laser and a method for using the same. BACKGROUND

[0002] Conventional semiconductor lasers (LD) have the advantages of small size, high efficiency and easy tuning, but also have inherent shortcomings such as wide laser output linewidth, obvious frequency drift, and great influence of temperature and current disturbance, which have not been solved.

[0003] In order to obtain narrow-linewidth laser output, an additional external cavity such as a Littrow external cavity, a Littman-Metcalf external cavity, or a plane mirror external cavity is usually constructed outside the LD. However, the plane mirror external cavity is sensitive to angle, difficult to adjust, and poor in stability, and a slight angle deviation will lead to a decrease in feedback efficiency, affecting the stability of the laser. The Littrow or Littman structure has a large volume and a complex external grating structure, resulting in great difficulty in production and adjustment of the laser, high optical processing cost, and extremely high requirement for optical axis stability of the external cavity feedback. Instability of the optical axis will lead to a decrease in feedback efficiency, resulting in a wide laser linewidth and easy mode hopping of the laser.

[0004] In view of this, it is urgent to overcome the defects of the prior art in the technical field. SUMMARY

[0005] The present application aims to solve the problem of poor overall stability of the structure of the existing external cavity semiconductor laser, leading to laser frequency drift and mode hopping.

[0006] The present application adopts the following technical solutions: In a first aspect, the present application provides a cat-eye external cavity semiconductor laser, comprising a housing 1 and a semiconductor refrigerator 2 arranged at the bottom of the housing 1, wherein the semiconductor refrigerator 2 is used to control the temperature of the laser to ensure the stability of the laser output wavelength and power. A laser tube 5 is arranged at the tail end of the housing 1, a cat-eye assembly 3 and a light filtering assembly 4 are arranged inside the housing 1, the light filtering assembly 4 is arranged between the cat-eye assembly 3 and the laser tube 5, the light filtering assembly 4 is used to select laser of a target wavelength, and the cat-eye assembly 3 is used to reflect laser of the target wavelength to the laser tube 5. An external cavity is formed between the laser exit surface of the laser tube 5 and the light splitting surface 300 of the cat-eye assembly 3, and the external cavity is arranged inside the housing 1, so that the cat-eye assembly 3, the laser tube 5, the light filtering assembly 4, the external cavity and the housing 1 form an integrated structure.

[0007] Further, the cat-eye assembly 3 comprises a light splitting flat sheet 30 and a cat-eye lens 31, the tail end of the light splitting flat sheet 30 is coated with a light splitting film, which can transmit and reflect laser light at a preset ratio; The tail end of the light splitting flat sheet 30 is provided with a light splitting surface 300, and there is a preset distance between the light splitting surface 300 and the cat-eye lens 31 to form a feedback cavity.

[0008] Further, the tail end of the light splitting flat sheet 30 is fixed with a piezoelectric ceramic 6, by controlling the voltage of the piezoelectric ceramic 6, the cavity length of the piezoelectric ceramic 6 can be adjusted, so as to adjust the position of the light splitting flat sheet 30, and realize the adjustment of the external cavity length.

[0009] Further, the cat-eye assembly 3 is arranged on a mounting seat 7, the tail end of the mounting seat 7 is provided with a cat-eye lens fixing hole 70, and a screw thread is arranged in the cat-eye lens fixing hole 70; A corresponding adjusting screw thread 310 is arranged on the shell of the cat-eye lens 31, the adjusting screw thread 310 is used for adjusting the screwing depth of the cat-eye lens 31, so that the focal point of the cat-eye lens 31 falls on the light splitting surface 300.

[0010] Further, the piezoelectric ceramic 6 is also arranged on the mounting seat 7, the inner diameter of the mounting seat 7 is greater than the outer diameter of the piezoelectric ceramic 6, so that the piezoelectric ceramic 6 can be accommodated in the mounting seat 7, and one end of the piezoelectric ceramic 6 is fixed on the mounting seat 7 through an adhesive, and the other end of the piezoelectric ceramic 6 is bonded with the light splitting flat sheet 30 through an adhesive.

[0011] Further, the light filtering assembly 4 comprises a light filtering sheet 40 and an angle adjusting rod 41, the light filtering sheet 40 is bonded on the angle adjusting rod 41, and the included angle between the light filtering sheet 40 and the laser light can be controlled through the angle adjusting rod 41, so as to realize the wavelength selection of the laser.

[0012] Further, the light filtering assembly 4 further comprises an angle adjusting knob 42 and a locking assembly 43, the upper end of the angle adjusting rod 41 is fixed with the angle adjusting knob 42, the angle adjusting knob 42 is used for rotating the angle adjusting rod 41 to a preset angle, and the locking assembly 43 is used for fixing the angle adjusting rod 41 at the preset angle.

[0013] Further, the shell 1 comprises an upper cover 10, a base 11 and a front cover 12, which are fixed together to form a containing space for containing the cat-eye assembly 3, the light filtering assembly 4 and the laser tube 5.

[0014] Furthermore, the filter assembly 4 is fixed on the base 11, and the upper cover 10 is provided with a first through hole 100. The angle adjustment knob 42 protrudes from the first through hole 100 to reduce the height of the laser.

[0015] In a second aspect, the present invention provides a method of using a cat-eye external cavity semiconductor laser, comprising: The collimated laser is emitted from the laser tube 5 to the cat's eye assembly 3, and the position of the cat's eye lens 31 is adjusted to ensure that the focus of the cat's eye lens 31 falls on the beam splitting surface 300, so as to maximize the feedback efficiency. Install the filter assembly 4 and adjust the filter assembly 4 to a preset angle. Select the target wavelength of laser through the filter assembly 4, and then feed it back to the laser tube 5 through the cat's eye assembly 3. By controlling the voltage of the piezoelectric ceramic 6, the position of the beam-splitting surface 300 is further adjusted so that the length of the outer cavity corresponds to the target wavelength, thereby forming resonance with the target wavelength. During laser operation, the temperature of the laser is controlled by the semiconductor cooler 2 to achieve highly stable laser output.

[0016] The beneficial effects of this invention are as follows: by integrating the cat's eye component, laser tube, filter component and outer cavity into the shell, the overall stability of the structure is improved and the vibration resistance of the laser is optimized; the semiconductor cooler located at the bottom of the shell can effectively control the overall temperature of the laser and improve the laser's resistance to temperature drift; the angle of the filter component is adjustable, which effectively improves the tuning range and tuning accuracy of the laser. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of a cat's-eye external cavity semiconductor laser provided in Embodiment 1 of the present invention; Figure 2 This is an exploded view of the overall structure of a cat's-eye external cavity semiconductor laser provided in Embodiment 1 of the present invention; Figure 3 This is an exploded structural diagram of a cat's eye assembly, piezoelectric ceramic, and mounting base provided in Embodiment 1 of the present invention; Figure 4This is a schematic cross-sectional view of the structure of a cat's eye component, piezoelectric ceramic, and mounting base along AA provided in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the structure of a shell provided in Embodiment 1 of the present invention; Figure 6 This is an exploded view of the structure of a filter assembly provided in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the structure of a locking component provided in Embodiment 1 of the present invention; Figure 8 This is a schematic cross-sectional view of a filter assembly and housing along AA provided in Embodiment 1 of the present invention; Figure 9 This is a flowchart illustrating the usage method of a cat's eye type external cavity semiconductor laser provided in Embodiment 1 of the present invention.

[0019] The reference numerals in the accompanying drawings are: 1. Outer shell, 10. Top cover, 100. First through hole, 11. Base, 110. Threaded hole, 12. Front cover, 120. Fixing base, 121. Second collimating lens, 2. Semiconductor cooler, 3. Cat's eye assembly, 30. Beam splitter, 300. Cat's eye lens, 31. Adjustment thread, 310. Filter assembly, 40. Filter, 41. Angle adjustment rod, 410. First annular boss, 411. Second annular boss, 412. First stop surface, 413. First fixing hole, 42. Angle adjustment knob, 43. Locking assembly, 43. Second through hole, 430. Locking plate, 431. Locking ring, 432. Second stop surface, 433. Second fixing hole, 434. Laser tube, 5. First collimating lens, 50. Piezoelectric ceramic, 6. Mounting base, 70. Cat's eye lens fixing hole, 8. Marking. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0022] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0023] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling," "wireless connection," etc. The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0024] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Example 1: When laser light of the target wavelength is reflected back to the laser tube within the corresponding cavity length, a target wavelength resonance is formed, thereby exciting laser oscillation. Laser light of other frequencies is suppressed to obtain a narrow linewidth laser for atomic physics experiments, lidar, or precision spectral measurements. Typically, an external cavity is built outside the LD to achieve the narrow linewidth laser output. However, external cavity feedback requires a highly stable optical axis. Instability of the optical axis leads to reduced feedback efficiency, resulting in a wider laser linewidth and potentially causing frequency jumps. To ensure optical axis stability, existing external cavity semiconductor lasers use a cat's-eye reflection structure instead of a Littrow or Littman structure. The cat's-eye reflection structure can automatically compensate for optical axis translation characteristics and is a highly coupled and stable external cavity reflection structure. Therefore, narrow linewidth lasers based on cat's-eye external cavities have higher structural stability and feedback efficiency.

[0026] Specifically, the formula for the Schawlow-Townes linewidth of the laser is: ,in The linewidth is P, the output power is t. p This is the average round-trip time of a photon within the cavity; while the equivalent cavity length of the cat's-eye external cavity is... ,in For the laser chip cavity length, The external cavity length of the laser, This represents the feedback coupling efficiency of the laser's external cavity.

[0027] Furthermore, external cavity feedback increases the effective cavity length while decreasing the linewidth; the linewidth compression formula is as follows: That is, the linewidth compression ratio is Assuming , , Then it can be calculated that That is, the MHz linewidth can be compressed to KHz.

[0028] To obtain a narrow linewidth laser, Embodiment 1 of the present invention provides a cat's-eye external cavity semiconductor laser, see reference. Figures 1-3The laser includes a housing 1 and a semiconductor cooler 2 disposed at the bottom of the housing 1. The semiconductor cooler 2 is used to control the temperature of the laser to ensure the stability of the laser output wavelength and power. A laser tube 5 is disposed at the tail end of the housing 1. A cat's eye component 3 and a filter component 4 are disposed inside the housing 1. The filter component 4 is disposed between the cat's eye component 3 and the laser tube 5. The filter component 4 is used to select the laser of the target wavelength. The cat's eye component 3 is used to reflect the laser of the target wavelength to the laser tube 5. An outer cavity is formed between the laser emission surface of the laser tube 5 and the beam splitting surface 300 of the cat's eye component 3. The outer cavity is disposed inside the housing 1, so that the cat's eye component 3, the laser tube 5, the filter component 4, the outer cavity and the housing 1 form an integrated structure.

[0029] The integrated design places the cat's eye component 3, laser tube 5, filter component 4, and outer cavity inside the housing 1, improving the overall stability of the structure and optimizing the vibration resistance of the laser. The semiconductor cooler 2 located at the bottom of the housing 1 can effectively control the overall temperature of the laser, improving the laser's resistance to temperature drift. The angle of the filter component is adjustable, effectively improving the tuning range and tuning accuracy of the laser.

[0030] Prolonged operation of a laser can lead to temperature increases, and high-temperature environments can affect the laser beam path. To address this issue, a space is provided at the bottom of the laser housing 1 to accommodate and fix the thermoelectric cooler 2, allowing the thermoelectric cooler 2 to cover the lower surface of the housing 1, thereby achieving uniform temperature control of the entire laser.

[0031] In order to reflect the laser output from the laser tube 5 back to the laser tube 5 to form optical oscillation, a cat's eye component 3 is provided at the front end of the laser tube 5. The cat's eye component 3 can reflect the laser back to the laser tube 5 along the original optical path. Specifically, a first collimating lens 50 is provided at the front end of the laser tube 5. The laser is collimated by the first collimating lens 50 and then emitted to the cat's eye component 3. It is reflected along the original optical path by the beam splitting surface 300 of the cat's eye component 3. The distance between the beam splitting surface 300 and the emission surface of the first collimating lens 50 is the length of the outer cavity.

[0032] A filter assembly 4 is also provided between the cat's eye assembly 3 and the first collimating lens 50. The filter assembly 4 receives the laser light incident from the laser tube 5 and selects the target wavelength laser light to emit to the cat's eye assembly 3. Specifically, the filter assembly 4 is rotatable. The filter assembly 4 is rotated to the corresponding angle according to the target wavelength so as to select the target wavelength laser light and feed it back to the laser tube 5 through the cat's eye assembly 3.

[0033] It should be noted here that, with Figure 2Taking a specific perspective as an example, the front end of the laser tube 5 refers to the left end of the laser tube 5. In this embodiment, the front end is based on... Figure 2 The orientations shown are described only for the purpose of illustrative purposes and are not intended to require the invention to be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0034] To achieve the reflection function and ensure that the laser returns along the original optical path, see [reference needed]. Figure 3 and Figure 4 The cat-eye component 3 includes a beam-splitting flat plate 30 and a cat-eye lens 31. The tail end of the beam-splitting flat plate 30 is coated with a beam-splitting film, which can transmit and reflect laser light at a preset ratio. The tail end of the beam-splitting flat plate 30 is set as a beam-splitting surface 300, and there is a preset distance between the beam-splitting surface 300 and the cat-eye lens 31 to form a feedback cavity. In actual use scenarios, the preset ratio can be 80% transmission and 20% reflection, or it can be set to 75% transmission and 25% reflection, and the specific ratio is determined according to the actual situation.

[0035] The beam splitter 30 is positioned in front of the cat's eye lens 31, so that the laser can propagate to the cat's eye lens 31 after being reflected by the beam splitter 300. In a preferred embodiment, the cat's eye lens 31 is configured as a cat's eye lens. Since the cat's eye lens has self-collimating characteristics, the laser reflected under vibration can still return along the original optical path without angular deviation, thereby reducing the influence of the environment on the laser frequency.

[0036] To maximize the returned laser power, please refer to [link / reference needed]. Figure 3 and Figure 4 The cat-eye component 3 is mounted on the mounting base 7. The mounting base 7 has a cat-eye lens fixing hole 70 at its tail end, and the cat-eye lens fixing hole 70 has a thread. The outer shell of the cat-eye lens 31 has a corresponding adjusting thread 310, which is used to adjust the screw depth of the cat-eye lens 31 so that the focal point of the cat-eye lens 31 falls on the beam splitting surface 300.

[0037] The beam splitter 30 is disposed at the front end of the mounting base 7, and the cat's eye lens 31 is detachably disposed in the cat's eye lens fixing hole 70. By adjusting the engagement depth of the adjusting thread 310 with the cat's eye lens fixing hole 70, the distance between the cat's eye lens 31 and the beam splitter 30 can be precisely adjusted to ensure the highest feedback efficiency. The adjusting thread 310 has a mark 8 at its tail end to confirm the installation direction of the cat's eye lens 31. In actual use, the mark 8 can be set as a groove.

[0038] To secure the beam splitter 30 and the mounting base 7, please refer to [link / reference needed]. Figure 4The piezoelectric ceramic 6 is also disposed on the mounting base 7. The inner diameter of the mounting base 7 is larger than the outer diameter of the piezoelectric ceramic 6, so that the piezoelectric ceramic 6 can be accommodated in the mounting base 7. One end of the piezoelectric ceramic 6 is fixed to the mounting base 7 by adhesive, and the other end of the piezoelectric ceramic 6 is bonded to the beam splitter 30 by adhesive.

[0039] In one embodiment, the piezoelectric ceramic 6 is disposed at the front end of the cat's eye lens fixing hole 70, and the tail end of the piezoelectric ceramic 6 is fixed to the front end of the cat's eye lens fixing hole 70 by an adhesive. The front end of the piezoelectric ceramic 6 is a free end, and the beam splitting surface 300 of the beam splitting plane is fixed to the free end of the piezoelectric ceramic 6 by an adhesive. In actual use, the adhesive can be a two-component epoxy resin adhesive, an acrylic structural adhesive, or a low-temperature curing epoxy adhesive, etc. In order to ensure the fixing effect, in a preferred embodiment, the adhesive is a two-component epoxy resin adhesive.

[0040] To ensure the stability of the outer cavity length, please refer to [further details]. Figure 4 The tail end of the beam splitter 30 is fixed with a piezoelectric ceramic 6. By controlling the voltage of the piezoelectric ceramic 6, the cavity length of the piezoelectric ceramic 6 can be adjusted to adjust the position of the beam splitter 30 and realize the adjustment of the outer cavity length.

[0041] The length of the piezoelectric ceramic 6 can be controlled by adjusting the voltage transmitted to it. In one embodiment, since the tail end of the piezoelectric ceramic 6 is a fixed end, the position of the free end of the piezoelectric ceramic 6 changes accordingly with the change in the length of the piezoelectric ceramic 6, causing the position of the beam splitter 30 to also change axially. The length adjustment accuracy of the piezoelectric ceramic 6 can reach the picometer level. After initially confirming the position of the cat's eye lens 31 by adjusting the adjusting thread 310, the position of the beam splitter 30 can be further adjusted to ensure that the length of the outer cavity corresponds to the target wavelength. Furthermore, when the length of the outer cavity changes due to environmental influences during laser operation, the position of the beam splitter 30 can be changed by adjusting the working voltage of the piezoelectric ceramic 6, so that the length of the outer cavity remains constant at the target value.

[0042] To form an integrated structure, see [reference] Figure 5 The outer casing 1 includes an upper cover 10, a base 11, and a front cover 12, which are fixed together to form a receiving space for accommodating the cat-eye component 3, the filter component 4, and the laser tube 5.

[0043] In one embodiment, the upper cover 10 is fixed to the upper end of the base 11 by at least one bolt, the front cover 12 is fixed to the front end of the base 11 by at least one bolt, and the upper cover 10 and the front cover 12 are also fixed together by bolts. The filter assembly 4, the mounting base 7, the laser tube 5, etc. are all fixed inside the outer shell 1 to improve the overall structural stability.

[0044] The base 11 is provided with a threaded hole 110 for fixing the laser tube 5 to the base 11. Furthermore, the base 11 is also provided with a cable outlet (not shown in the figure) for leading out the cable of the piezoelectric ceramic 6 to connect to the controller.

[0045] In order to output laser and couple with other components, in one embodiment, a mounting base 120 is provided on the front cover 12. The mounting base 120 has a mounting hole for accommodating and fixing a second collimating lens 121. The second collimating lens 121 is used to collimate the laser transmitted by the beam splitter 30 and output it to the next component. The mounting base 120 is fixed to the front cover 12 by bolts.

[0046] To achieve wavelength control, see [link / reference] Figure 6 and Figure 7 The filter assembly 4 includes a filter 40 and an angle adjustment rod 41. The filter 40 is bonded to the angle adjustment rod 41. The angle adjustment rod 41 can control the angle between the filter 40 and the laser to achieve wavelength selection of the laser.

[0047] The angle adjustment rod 41 is disposed inside the housing 1. The filter 40 is fixed to the lower end of the angle adjustment rod 41. The upper end of the angle adjustment rod 41 protrudes from the upper surface of the upper cover 10 to facilitate operation of the angle adjustment rod 41. By rotating the angle adjustment rod 41, the filter 40 is also rotated, thereby changing the angle between the filter 40 and the reflected laser. The angle of the filter is adjusted until it corresponds to the target wavelength, so that the laser of the target wavelength is transmitted to the laser tube 5.

[0048] To adjust the angle of the angle adjustment lever 41, please refer to [link / reference needed]. Figure 6 and Figure 7 The filter assembly 4 further includes an angle adjustment knob 42 and a locking assembly 43. The upper end of the angle adjustment rod 41 is fixed with the angle adjustment knob 42. The angle adjustment knob 42 is used to rotate the angle adjustment rod 41 to a preset angle. The locking assembly 43 is used to fix the angle adjustment rod 41 at the preset angle.

[0049] In one embodiment, the angle adjusting rod 41 is provided with a first annular boss 410 and a second annular boss 411. The first annular boss 410 is located at the upper end of the second annular boss 411, and the diameter of the first annular boss 410 is smaller than that of the second annular boss 411, so that a first stop surface 412 is formed around the first annular boss 410 on the upper surface of the second annular boss 411, which is used to limit the relative position of the angle adjusting rod 41 and the locking assembly 43. The upper end of the angle adjusting rod 41 is provided with a first fixing hole 413. The first fixing hole 413 and the bolt are connected by threads to fix the angle adjusting knob 42 and the angle adjusting rod 41, so that the angle adjusting rod 41 can be rotated by rotating the adjusting knob to rotate the angle adjusting rod 41 to a preset angle.

[0050] The locking assembly 43 includes a locking plate 431 and a locking ring 432. A second through hole 430 is disposed on the locking plate 431, and the locking ring 432 is fixed to the lower end of the locking plate 431. The diameter of the locking ring 432 is larger than the diameter of the second through hole 430, forming a second stop surface 433 at the lower end of the locking plate 431. A first annular boss 410 is accommodated within the second through hole 430, and the first stop surface 412 is fitted against the second stop surface 433. The inner diameter of the locking ring 432 is the same as the outer diameter of the second annular boss 411, which is accommodated within the locking ring 432. In one embodiment, the locking ring 432 can be a collar, which applies a centripetal force to the second annular boss 411 to fix the locking assembly 43 and the angle adjusting rod 41, thereby fixing the angle adjusting rod 41 at a preset angle.

[0051] To ensure a secure hold, in a preferred embodiment, the locking ring 432 is an annular component with a first locking portion and a second locking portion formed at both ends. By adjusting the distance between the first locking portion and the second locking portion, a centripetal force can be applied to the second annular boss 411 to secure the locking assembly 43 and the angle adjusting rod 41, thereby fixing the angle adjusting rod 41 at a preset angle.

[0052] See Figure 7 and Figure 8 The filter assembly 4 is fixed on the base 11. Specifically, the locking plate 431 is provided with at least one second fixing hole 434. The second fixing hole 434 and the bolt are connected by threads to fix the locking plate 431 and the base 11 together.

[0053] In one embodiment, the thickness of the upper cover 10 is greater than the height of the angle adjustment knob 42. A fixing groove (not shown in the figure) is provided on the lower surface of the upper cover 10. The fixing groove corresponds to the angle adjustment knob 42 and is used to accommodate the angle adjustment knob 42. The angle of the filter 40 is adjusted to correspond to the target wavelength using the angle adjustment knob 42. Then, the locking screw of the locking assembly 43 of the angle adjustment rod 42 is tightened to fix the angle of the filter 40. The frequency selection function of the filter 40 is used to select the laser of the target wavelength.

[0054] In order to reduce the structural height, combined with Figure 5 , Figure 7 and Figure 8 In a preferred embodiment, the upper cover 10 is provided with a first through hole 100, and the angle adjustment knob 42 protrudes from the first through hole 100 to reduce the height of the laser. Specifically, the thickness of the upper cover 10 is less than the height of the angle adjustment knob 42, and the first through hole 100 is used to accommodate the angle adjustment knob 42, so that the angle adjustment knob 42 can protrude from the first through hole 100 to reduce the structural height.

[0055] Example 2: See Figure 9 Embodiment 2 of the present invention provides a method for using a cat-eye external cavity semiconductor laser, comprising: In step 101, a collimated laser is emitted from the laser tube 5 to the cat's eye assembly 3, and the position of the cat's eye lens 31 is adjusted to ensure that the focus of the cat's eye lens 31 falls on the beam splitting surface 300, so as to maximize the feedback efficiency.

[0056] In one embodiment, the laser tube 5 is disposed inside the laser tube sleeve, the first collimating lens 50 is fixed to one end of the laser tube sleeve near the cat's eye assembly 3, the laser tube 5 is fixed to the other end of the laser tube sleeve, the laser tube sleeve and the mounting base 7 are fixed to the base 11, the tail end of the piezoelectric ceramic 6 and the front end of the cat's eye lens fixing hole 70 are fixed together with adhesive, and the free end of the piezoelectric ceramic 6 and the beam splitting surface 300 are fixed. After the laser is collimated by the first collimating lens 50, it is emitted and then focused onto the beam splitting surface 300 by the lens 31. The beam splitting surface 300 reflects the laser onto the cat's eye lens 31. The cat's eye lens 31 is fixed in the cat's eye lens fixing hole 70, and the cat's eye lens fixing hole 70 and the adjusting thread 310 are screwed together by a threaded connection. The screwing depth is adjusted to adjust the relative position of the beam splitting surface 300 and the cat's eye lens 31 so that the focal point of the cat's eye lens 31 falls on the beam splitting surface 300, ensuring that the reflected laser power reaches the maximum value and the feedback efficiency is the highest. After debugging, the beam splitter 300 reflects the laser back to the laser tube 5 along the cat's eye component 3, the filter component 4 and the first collimating lens 50, thereby extending the laser cavity length and narrowing the linewidth by hundreds or even thousands of times.

[0057] In step 102, the filter assembly 4 is installed and adjusted to a preset angle. The target wavelength of the laser is selected through the filter assembly 4 and then fed back to the laser tube 5 through the cat's eye assembly 3.

[0058] After the cat-eye assembly 3 is debugged, the angle adjustment rod 41 is passed through the second through hole 430 from the lower end until the first stop surface 412 abuts against the second stop surface 433. The first annular protrusion is accommodated in the second through hole 430, and the second annular protrusion is accommodated in the locking ring 432. The filter 40 is fixed at the lower end of the angle adjustment rod 41, and the first fixing hole 413 and the bolt are connected by threads to fix the angle adjustment knob 42 at the upper end of the angle adjustment rod 41. The angle adjustment rod 41 is rotated so that the filter 40 is rotated to the angle corresponding to the target wavelength laser. The locking ring 432 is fixed together with the second annular protrusion so that the target wavelength laser can be emitted to the laser tube 5. Align the first through hole 100 with the angle adjustment knob 42, fix the upper cover 10 and the base 11 so that the angle adjustment knob 42 can be exposed from the first through hole 100. Rotate the angle adjustment knob 42 so that the filter 40 is adjusted to the angle corresponding to the target wavelength. The laser of the target wavelength passes through the filter 40 and is emitted to the cat's eye assembly 3. The laser reflected back by the cat's eye lens 31 will be automatically calibrated to the original optical path. The laser of the target wavelength is reflected back to the laser tube 5 through the cat's eye assembly 3 to form a laser resonance of a specific wavelength.

[0059] Specifically, the laser from the laser tube 5 is adjusted to be near the target wavelength and then emitted to the cat's eye assembly 3. After passing through the lens 31, its focus falls on the beam splitting surface 300 of the beam splitter 30 to form a reflection. The reflected laser returns along the original optical path, passes through the lens 31, the filter 40 and the first collimating lens 50 and is fed back to the laser tube 5, where it coherently superimposes with the inner cavity of the laser tube 5, thereby achieving the purpose of selecting a specific wavelength of laser and obtaining a significant power gain in this band.

[0060] In step 103, the position of the beam-splitting surface 300 is further adjusted by controlling the voltage of the piezoelectric ceramic 6 so that the length of the outer cavity corresponds to the target wavelength, thereby forming a target wavelength resonance.

[0061] The cable of the piezoelectric ceramic 6 is led out from the outlet. By controlling the voltage of the piezoelectric ceramic 6, the length of the piezoelectric ceramic 6 is adjusted, causing the position of the free end of the piezoelectric ceramic 6 to change, which in turn causes the position of the beam splitter 30 to change. This further adjusts the distance between the beam splitter 300 and the cat's eye lens 31, making the length of the outer cavity consistent with the resonant cavity length corresponding to the target wavelength, so as to excite laser oscillation. Furthermore, the length of the piezoelectric ceramic 6 can be adjusted more precisely to meet the needs of special industries, such as the excitation of energy levels of alkali metal atoms such as rubidium and cesium by laser. The piezoelectric ceramic 6 can also be locked to a specific length using precision electronics to lock the wavelength of the laser to certain special bands. For example, the saturation absorption spectrum of the hyperfine energy levels of rubidium and cesium at a specific wavelength of laser light can be used as a feedback signal to keep the laser corresponding to the position of the piezoelectric ceramic on the absorption spectrum line, so as to meet the needs of industries such as cold atom interferometers, neutral atom quantum computing, and atomic frequency standards.

[0062] In step 104, during the operation of the laser, the temperature of the laser is controlled by the semiconductor cooler 2 to achieve highly stable laser output.

[0063] The semiconductor cooler 2 keeps the laser at a preset operating temperature, preventing the laser from overheating and affecting the optical path, thus improving the laser's resistance to temperature drift and achieving highly stable narrow linewidth laser output.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cat-eye type external cavity semiconductor laser, characterized in that, It includes a housing (1) and a semiconductor cooler (2) disposed at the bottom of the housing (1). The semiconductor cooler (2) is used to control the temperature of the laser to ensure the stability of the laser output wavelength and power. A laser tube (5) is provided at the tail end of the outer shell (1). A cat's eye component (3) and a filter component (4) are provided inside the outer shell (1). The filter component (4) is located between the cat's eye component (3) and the laser tube (5). The filter component (4) is used to select the target wavelength of the laser. The cat's eye component (3) is used to reflect the target wavelength of the laser to the laser tube (5). An outer cavity is formed between the laser emission surface of the laser tube (5) and the beam splitting surface (300) of the cat eye assembly (3). The outer cavity is located inside the outer shell (1), so that the cat eye assembly (3), the laser tube (5), the filter assembly (4), the outer cavity and the outer shell (1) form an integrated structure.

2. The cat-eye external cavity semiconductor laser according to claim 1, characterized in that, The cat-eye component (3) includes a beam splitter (30) and a cat-eye lens (31). The tail end of the beam splitter (30) is coated with a beam splitting film, which can transmit and reflect laser light according to a preset ratio. The tail end of the beam splitter (30) is set as a beam splitting surface (300), and there is a preset distance between the beam splitting surface (300) and the cat's eye lens (31) to form a feedback cavity.

3. The cat-eye external cavity semiconductor laser according to claim 2, characterized in that, The tail end of the beam splitter (30) is fixed with a piezoelectric ceramic (6). By controlling the voltage of the piezoelectric ceramic (6), the cavity length of the piezoelectric ceramic (6) can be adjusted to adjust the position of the beam splitter (30) and realize the adjustment of the outer cavity length.

4. The cat-eye external cavity semiconductor laser according to claim 3, characterized in that, The cat eye component (3) is mounted on the mounting base (7), and the tail end of the mounting base (7) is provided with a cat eye lens fixing hole (70), and the cat eye lens fixing hole (70) is provided with a thread; The outer shell of the cat's eye lens (31) is provided with a corresponding adjustment thread (310). The adjustment thread (310) is used to adjust the engagement depth of the cat's eye lens (31) so that the focal point of the cat's eye lens (31) falls on the beam splitting surface (300).

5. The cat-eye external cavity semiconductor laser according to claim 4, characterized in that, The piezoelectric ceramic (6) is also disposed on the mounting base (7). The inner diameter of the mounting base (7) is larger than the outer diameter of the piezoelectric ceramic (6), so that the piezoelectric ceramic (6) can be accommodated in the mounting base (7). One end of the piezoelectric ceramic (6) is fixed to the mounting base (7) by adhesive, and the other end of the piezoelectric ceramic (6) is bonded to the beam splitter (30) by adhesive.

6. The cat-eye external cavity semiconductor laser according to claim 1, characterized in that, The filter assembly (4) includes a filter (40) and an angle adjustment rod (41). The filter (40) is attached to the angle adjustment rod (41). The angle adjustment rod (41) can control the angle between the filter (40) and the laser to achieve wavelength selection of the laser.

7. The cat-eye external cavity semiconductor laser according to claim 6, characterized in that, The filter assembly (4) further includes an angle adjustment knob (42) and a locking assembly (43). The upper end of the angle adjustment rod (41) is fixed with the angle adjustment knob (42). The angle adjustment knob (42) is used to rotate the angle adjustment rod (41) to a preset angle. The locking assembly (43) is used to fix the angle adjustment rod (41) at the preset angle.

8. The cat-eye external cavity semiconductor laser according to claim 7, characterized in that, The outer casing (1) includes an upper cover (10), a base (11) and a front cover (12), which are fixed together to form a receiving space for accommodating the cat-eye assembly (3), the filter assembly (4) and the laser tube (5).

9. The cat-eye external cavity semiconductor laser according to claim 8, characterized in that, The filter assembly (4) is fixed on the base (11), and the upper cover (10) is provided with a first through hole (100). The angle adjustment knob (42) protrudes from the first through hole (100) to reduce the height of the laser.

10. A method of using a cat's-eye type external cavity semiconductor laser, characterized in that, Using the cat-eye external cavity semiconductor laser as described in any one of claims 1 to 9, comprising: The collimated laser is emitted from the laser tube (5) to the cat eye assembly (3), and the position of the cat eye lens (31) is adjusted to ensure that the focus of the cat eye lens (31) falls on the beam splitting surface (300) so as to maximize the feedback efficiency; Install the filter assembly (4) and adjust the filter assembly (4) to a preset angle. Select the target wavelength of laser through the filter assembly (4) and then feed it back to the laser tube (5) through the cat's eye assembly (3). By controlling the voltage of the piezoelectric ceramic (6), the position of the beam splitter (300) is further adjusted so that the length of the outer cavity corresponds to the target wavelength, so as to form a target wavelength resonance. During the operation of the laser, the temperature of the laser is controlled by a semiconductor cooler (2) to achieve highly stable laser output.

Images