Cat-eye external cavity semiconductor laser with wide scanning range without mode hopping

Abstract

The application relates to a cat-eye external cavity semiconductor laser with a wide jump-free scanning range, which comprises a laser collimation filter structure and a cat-eye tuning structure; the cat-eye tuning structure comprises a linear guide rail, a piezoelectric ceramic, a cat-eye lens mounting seat, a cat-eye lens, a partial mirror and a collimation output lens; the piezoelectric ceramic and the cat-eye lens mounting seat are both mounted on the linear guide rail; the cat-eye lens mounting seat is fixed with one end of the linear guide rail through the piezoelectric ceramic; the length change of the piezoelectric ceramic makes the cat-eye lens mounting seat slide relative to the linear guide rail; the relative positions of the cat-eye lens, the partial mirror and the collimation output lens are fixed, and they are all mounted on the cat-eye lens mounting seat; the cat-eye lens converges parallel laser of a specific wavelength range, and the focal point is located on the partial mirror; the collimation output lens performs beam shaping on the convergent laser passing through the partial mirror, and outputs parallel laser of a specific frequency.

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 with wide scanning range without mode hopping. BACKGROUND

[0002] External cavity semiconductor lasers have the advantages of wide tunable range, narrow linewidth, large wavelength coverage, and are widely used in atomic physics, laser spectroscopy, quantum precision measurement, optical communication, etc. The external cavity semiconductor laser extends the resonant cavity to the outside of the laser tube and realizes external light resonance by using optical feedback elements. The great increase in resonant cavity length effectively narrows the laser linewidth. The existing grating external cavity semiconductor laser changes the center wavelength of the laser in a large range by fine-tuning the external cavity grating. However, the wavelength adjustment procedure of the grating external cavity semiconductor laser is relatively cumbersome and prone to mode hopping. It also changes the output angle of the laser, causing changes in the subsequent optical path. Moreover, it has high requirements for mechanical stability and is not suitable for portable scenarios.

[0003] Cat-eye semiconductor lasers have low cost and high stability. The addition of a cat-eye lens allows the cat-eye semiconductor laser to be tuned over a large range without affecting the direction of the output laser. At the same time, the cat-eye semiconductor laser is not sensitive to optical path shifts and has good mechanical and thermal stability. However, the existing cat-eye semiconductor laser has the disadvantage of being prone to mode hopping. SUMMARY

[0004] Therefore, the present application aims to provide a cat-eye external cavity semiconductor laser with wide scanning range without mode hopping.

[0005] A cat-eye external cavity semiconductor laser with wide scanning range without mode hopping, comprising a laser collimation filter structure and a cat-eye tuning structure; the laser collimation filter structure is used to emit parallel laser of a specific wavelength range; the cat-eye tuning structure is used to tune the parallel laser emitted by the laser collimation filter structure and output parallel laser of a specific frequency.

[0006] The cat-eye tuning structure comprises a linear guide rail, a piezoelectric ceramic, a cat-eye lens mounting seat, a cat-eye lens, a partial mirror and a collimation output lens; the piezoelectric ceramic and the cat-eye lens mounting seat are both mounted on the linear guide rail; the cat-eye lens mounting seat is fixed to one end of the linear guide rail through the piezoelectric ceramic; the length change of the piezoelectric ceramic causes the cat-eye lens mounting seat to slide relative to the linear guide rail.

[0007] The relative positions of the cat-eye lens, the partial mirror and the collimating output lens are fixed, and all are mounted on the cat-eye lens mounting seat; the cat-eye lens converges the parallel laser of the specific wavelength range, and the focal point is located on the partial mirror; the collimating output lens collects and shapes the convergent laser passing through the partial mirror, and outputs the parallel laser of the specific frequency.

[0008] The partial mirror mounting seat and the collimating output lens mounting seat are both fixedly mounted on the cat-eye lens mounting seat, the cavity length is adjusted by adjusting the position of the cat-eye lens mounting seat, thereby avoiding the problems of mode jumping, output light intensity jitter and unstable operation of the laser caused by directly adjusting the position of the partial mirror, and the stability of the cat-eye external cavity semiconductor laser is greatly improved.

[0009] Further, the laser collimation filter structure comprises a laser shell, a laser diode, a collimating lens and a narrow-band filter; the laser shell comprises a main accommodating portion, a secondary accommodating portion and a C-shaped connecting portion;

[0010] One end of the main accommodating portion and the secondary accommodating portion is fixedly connected through the C-shaped connecting portion, and the other end is separated; the laser diode and the collimating lens are mounted in the main accommodating portion, and the narrow-band filter is mounted in the secondary accommodating portion;

[0011] The laser diode emits dispersed light; the collimating lens collects and shapes the dispersed light emitted by the laser diode into parallel light; the narrow-band filter selects the frequency of the parallel light to convert it into parallel laser of a specific wavelength range;

[0012] By changing the angle formed by the main accommodating portion and the secondary accommodating portion, the incident angle of the parallel light entering the narrow-band filter can be changed, and further the center frequency of the parallel laser of the specific wavelength range can be changed.

[0013] Further, the laser collimation filter structure further comprises a precision screw; the main accommodating portion is further provided with a precision screw mounting hole; the precision screw is mounted in the precision screw mounting hole, and the screw end face thereof protrudes out of the precision screw mounting hole and abuts against the secondary accommodating portion.

[0014] Further, the laser collimation filter structure further comprises a laser diode snap ring provided with a pin positioning hole; the side of the main accommodating portion away from the secondary accommodating portion is provided with a laser diode mounting hole; the laser diode snap ring is fixedly mounted in the laser diode mounting hole; the laser diode comprises a lamp bead and a pin; wherein the lamp bead is located inside the main accommodating portion, and the pin protrudes out of the main accommodating portion through the pin positioning hole of the laser diode snap ring.

[0015] Further, the laser collimation filter structure further comprises: an O-ring; the collimation lens is installed on one side of the main accommodating portion close to the auxiliary accommodating portion, and is installed in the main accommodating portion through the internal thread provided in the main accommodating portion; the O-ring is fixedly sleeved on the outer periphery of the collimation lens, and fills the gap between the collimation lens and the internal thread in the main accommodating portion for fixing the collimation lens.

[0016] Further, a vacuum system is further included, and the vacuum system comprises: a vacuum system housing, a vacuum system cover, and a window lens; the vacuum system housing is a top-opened cuboid box structure; the vacuum system cover is arranged on the top of the cuboid box structure to form a closed cuboid box structure together with the vacuum system housing; the laser collimation filter structure and the cat-eye tuning structure are both installed in the interior of the cuboid box structure; a light outlet window is arranged on the front of the cuboid box structure; and the window lens is fixedly installed in the light outlet window.

[0017] Further, the vacuum system further comprises: an angle valve and a small ion pump; one side of the cuboid box structure is provided with an angle valve mounting hole; the angle valve is provided with a top outlet, a bottom outlet and a side outlet; the top outlet of the angle valve is in butt joint with the angle valve mounting hole; the side outlet is connected with the small ion pump; the bottom outlet is connected with an external vacuum pump during vacuumizing and is sealed after vacuumizing is completed; during vacuumizing, the bottom outlet of the angle valve is opened, the pump head of the vacuum pump is connected with the bottom outlet for vacuumizing treatment; after vacuumizing is completed, the pump head of the vacuum pump is pulled out, the bottom outlet is sealed, and the small ion pump is started.

[0018] Further, the vacuum system further comprises: a semiconductor refrigerating sheet; the upper and lower surfaces of the semiconductor refrigerating sheet are both smeared with heat-conducting silicone grease; the lower surface of the semiconductor refrigerating sheet contacts the bottom of the vacuum system housing, and the upper surface thereof contacts the laser collimation filter structure; the semiconductor refrigerating sheet provides heating or cooling effect according to the temperature detected by the thermistor arranged in the interior of the laser collimation filter structure, so as to maintain the temperature of the vacuum system and the laser collimation filter structure.

[0019] Further, an isolator for preventing external light from entering the interior of the laser is further included; the bottom end of the front of the cuboid box structure extends out an isolator mounting plate; the isolator is mounted on the isolator mounting plate; the laser of the specific frequency can pass through the window lens to enter the isolator.

[0020] Further, the cat-eye tuning structure further comprises: a partial mirror mounting seat and a collimation output lens mounting seat; the cat-eye lens mounting seat comprises a base and a cat-eye lens mounting portion.

[0021] The bottom of the base is mounted on the linear guide rail, and the top is provided with two rows of screw holes arranged at equal intervals; the cat-eye lens mounting portion is vertically arranged at the end of the base away from the isolator, and forms an "L" type structure together with the base; the cat-eye lens mounting portion is provided with a cat-eye lens mounting port, and the cat-eye lens is mounted in the cat-eye lens mounting port;

[0022] The two ends of the bottom of the partial mirror mounting seat are each provided with a slot hole, and the interval of the two slot holes is equal to the interval of the two rows of screw holes of the base of the cat-eye lens mounting seat; when the two slot holes are respectively aligned with one pair of screw holes of the two rows of screw holes, two screws are respectively passed through a slot hole and a screw hole, so that the partial mirror mounting seat is fixedly mounted on the top of the base of the cat-eye lens mounting seat; the partial mirror mounting seat is provided with a partial mirror mounting port opposite to the cat-eye lens mounting port, and the partial mirror is mounted in the partial mirror mounting port;

[0023] The two ends of the bottom of the collimating output lens mounting seat are each provided with a slot hole, and the interval of the two slot holes is equal to the interval of the two rows of screw holes of the base of the cat-eye lens mounting seat; when the two slot holes are respectively aligned with one pair of screw holes of the two rows of screw holes, two screws are respectively passed through a slot hole and a screw hole, so that the collimating output lens mounting seat is fixedly mounted on the top of the base of the cat-eye lens mounting seat; the collimating output lens mounting seat is provided with a collimating output lens mounting port opposite to the partial mirror mounting port, and the collimating output lens is mounted in the collimating output lens mounting port.

[0024] In order to better understand and implement, the present application is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a whole structure diagram of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the present application;

[0026] Figure 2 It is a vacuum system structure schematic diagram of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the present application;

[0027] Figure 3 It is an installation schematic diagram of the laser collimating and filtering structure of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the present application;

[0028] Figure 4 It is an explosion schematic diagram of the laser collimating and filtering structure of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the present application;

[0029] Figure 5The structural schematic diagram of the cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the application;

[0030] Figure 6 The side view of the cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the application;

[0031] Figure 7 The sectional view of the cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the application;

[0032] Figure 8 The optical path schematic diagram of the cat-eye external cavity semiconductor laser of the application. DETAILED DESCRIPTION

[0033] The inventor found that the existing cat-eye semiconductor laser is prone to mode mutation during tuning, which shows the problem of unstable tuning. The inventor found that the existing cat-eye semiconductor laser performs frequency sweeping by directly adjusting the front and back positions of the partial reflector, which to some extent destroys the cat-eye structure, and further causes the feedback light intensity of the cat-eye semiconductor laser to change, and finally causes the mode hopping and other unstable working phenomena. Based on the above analysis, the application provides a cat-eye external cavity semiconductor laser with wide scanning range without mode hopping, which has the advantage of not destroying the cat-eye structure during tuning.

[0034] Please refer to Figure 1 , Figure 1 The overall structural diagram of the cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the application. The cat-eye external cavity semiconductor laser with wide scanning range without mode hopping of the application comprises a vacuum system 1, a laser collimation and filtering structure 2, a cat-eye tuning structure 3 and an isolator 4. The vacuum system 1 is used to provide a vacuum environment to improve the working stability of the cat-eye external cavity semiconductor laser. The laser collimation and filtering structure 2 and the cat-eye tuning structure 3 are both installed inside the vacuum system 1. The laser collimation and filtering structure 2 is used to emit parallel laser of a specific wavelength range. The cat-eye tuning structure 3 is used to tune the parallel laser emitted by the laser collimation and filtering structure 2, and output parallel laser of a specific frequency. The laser of a specific frequency output by the cat-eye tuning structure 3 is emitted through the isolator 4. The isolator 4 is used to prevent external light from entering the cat-eye external cavity semiconductor laser, so as to further improve the working stability of the cat-eye external cavity semiconductor laser.

[0035] Specifically, please refer to Figure 2 , Figure 2The schematic diagram of the vacuum system structure of the cat-eye external cavity semiconductor laser with wide jump-free scanning range according to the present application. The vacuum system 1 comprises a vacuum system shell 11, a vacuum system cover 12, a window lens 13, an angle valve 14 and a small ion pump 15.

[0036] The vacuum system shell 11 is a top-opened cuboid box structure. The vacuum system cover 12 is arranged on the top of the cuboid box structure to form a closed cuboid box structure together with the vacuum system shell 11. In one embodiment, the vacuum system shell 11 and the vacuum system cover 12 are connected by screws, and the gap is sealed by a rubber ring. The bottom end of the front part of the cuboid box structure extends an isolator mounting plate 111, and the isolator 4 is mounted on the isolator mounting plate 111 through an isolator mounting seat 41. The front part of the cuboid box structure is provided with an out-light window, and the window lens 13 is fixed in the out-light window by epoxy resin. The window lens 13 is made of transparent material, and the surface is coated with an anti-reflection film. The laser of a specific frequency can pass through the window lens 13 and enter the isolator 4.

[0037] Further, the bottom of the vacuum system shell 11 is provided with a semiconductor refrigeration piece (not shown in the figure). The upper and lower surfaces of the semiconductor refrigeration piece are coated with heat-conducting silicone grease; the lower surface contacts the bottom of the vacuum system shell 11, and the upper surface contacts the laser collimation filter structure 2. The semiconductor refrigeration piece provides heating or cooling effect according to the temperature detected by the thermistor arranged inside the laser collimation filter structure 2, so as to maintain the temperature of the vacuum system 1 and the laser collimation filter structure 2, thereby improving the working stability of the cat-eye external cavity semiconductor laser.

[0038] One side of the cuboid box structure is provided with an angle valve mounting hole, and the angle valve 14 is mounted on the outer side of the vacuum system shell 11 through the angle valve mounting hole. The angle valve 14 is provided with a top outlet, a bottom outlet and a side outlet. The top outlet of the angle valve 14 is connected with the angle valve mounting hole, so as to communicate the inside of the vacuum system 1; the side outlet is connected with the small ion pump 15; and the bottom outlet is connected with an external vacuum pump during vacuumizing and is sealed after vacuumizing. During vacuumizing, the bottom outlet of the angle valve 14 is opened, and the pump head of the external vacuum pump is connected with the bottom outlet for vacuumizing; after vacuumizing, the pump head of the vacuum pump is pulled out, and the bottom outlet is sealed, and the small ion pump 15 is started to maintain the vacuum environment in the vacuum system 1.

[0039] The other side of the cuboid box structure is provided with a navigation jack 112, and the related wires inside the cat-eye external cavity semiconductor laser are connected with the external controller through the navigation jack 112.

[0040] Specifically, refer to Figure 3 and Figure 4 , Figure 3 Figure 1 is a schematic diagram of the installation of the laser collimation filter structure of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range of the present application, Figure 4 Figure 2 is an exploded schematic diagram of the laser collimation filter structure of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range of the present application. The laser collimation filter structure 2 comprises a laser shell 21, a laser diode 22, a laser diode clamping ring 23, a collimation lens 24, an O-ring 25, a narrow-band filter 26, and a precision screw 27.

[0041] The laser shell 21 is installed inside the cuboid box structure, away from the side of the isolator 4, and is fixedly connected to the bottom of the vacuum system shell 11. The laser shell 21 comprises a main containing part 211, a secondary containing part 212, and a C-shaped connecting part 213. One end of the main containing part 211 and the secondary containing part 212 is fixedly connected through the C-shaped connecting part 213, and the other end is separated; that is, the main containing part 211 and the secondary containing part 212 form a clip-like structure through the C-shaped connecting part 213. The laser shell 21 is manufactured by an integral molding process.

[0042] The side of the main containing part 211 away from the secondary containing part 212 is provided with a laser diode mounting hole. The inner wall of the laser diode mounting hole is provided with an internal thread, and the outer circle of the laser diode clamping ring 23 is provided with an external thread. The laser diode clamping ring 23 is fixed in the laser diode mounting hole through the cooperation of the external thread and the internal thread. The center of the laser diode clamping ring 23 is provided with a pin positioning hole. The laser diode comprises a lamp bead and a pin. The lamp bead of the laser diode is installed inside the main containing part 211, and the pin extends out of the main containing part 211 through the pin positioning hole. The pin positioning hole of the laser diode clamping ring 23 is provided with a clamping tongue. When the pin is inserted into the pin positioning hole, the clamping tongue clamps the pin, thereby fixing the laser diode 22.

[0043] The collimating lens 24 is installed in the main accommodating portion 211 near the side of the sub-accommodating portion 212. In one embodiment, the collimating lens 24 is installed in the main accommodating portion 211 through the internal thread provided in the main accommodating portion 211. The O-ring 25 is fixedly sleeved on the outer periphery of the collimating lens 24 through epoxy resin, fills the gap between the collimating lens 24 and the internal thread in the main accommodating portion 211 for fixing the collimating lens 24, plays a role of supporting, increasing friction, and preventing the collimating lens from tilting or vibrating caused by the gap, thereby improving the stability of the collimating lens 24. The side of the main accommodating portion 211 near the sub-accommodating portion 212 is provided with a light-transmitting port, which is opposite to the collimating lens 24.

[0044] The sub-accommodating portion 212 is provided with a narrow-band filter mounting port opposite to the position of the collimating lens 24; the narrow-band filter 26 is installed in the narrow-band filter mounting port of the sub-accommodating portion 212. The laser diode 22, the collimating lens 24, and the narrow-band filter 26 are located on the same optical path. In one embodiment, the narrow-band filter 26 is fixed in the narrow-band filter mounting port of the sub-accommodating portion 212 through epoxy resin.

[0045] The laser diode 22 emits dispersed light; the collimating lens 24 collects and shapes the dispersed light emitted by the laser diode 22 into parallel light; the narrow-band filter 26 selects the frequency of the parallel light and converts it into parallel laser light of a specific wavelength range. The center frequency λ of the parallel laser light of the specific wavelength range is determined by the incident angle θ of the parallel light entering the narrow-band filter 26; specifically, the center frequency λ of the parallel laser light of the specific wavelength range and the incident angle θ of the parallel light entering the narrow-band filter satisfy the following formula:

[0046]

[0047] In the formula, λ is the center frequency of the parallel laser light of the specific wavelength range output by the narrow-band filter, θ is the incident angle of the parallel light entering the narrow-band filter, λ0 is the center frequency of the parallel laser light of the specific wavelength range output by the narrow-band filter when the parallel light is vertically incident on the narrow-band filter, n is the effective refractive index of the narrow-band filter. eff

[0048] ​The one end of the main accommodating part 211 separated from the secondary accommodating part 212 is provided with a precision screw mounting hole, and the precision screw mounting hole is provided with an internal thread; the precision screw 27 is mounted in the precision screw mounting hole of the main accommodating part 211; the screw end face of the precision screw 27 protrudes out of the precision screw mounting hole and abuts against the secondary accommodating part 212. By rotating the precision screw 27, the length of the screw end face protruding out of the precision screw mounting hole can be changed, so that the distance between the one end of the main accommodating part 211 and the secondary accommodating part 212 is changed, and the angle formed by the main accommodating part 211 and the secondary accommodating part 212 is changed. Rotating the precision screw 27 to adjust the length of the screw end face protruding out of the precision screw mounting hole can be completed by manual rotation or by the rotation of an electric actuator controlled by an external controller.

[0049] The incidence angle θ of the parallel light into the narrow-band filter is determined by the angle formed by the collimating lens 24 and the narrow-band filter 26. Since the collimating lens is mounted in the main accommodating part 211 and the narrow-band filter 26 is mounted in the secondary accommodating part 212, the angle formed by the collimating lens 24 and the narrow-band filter 26 is determined by the angle formed by the main accommodating part 211 and the secondary accommodating part 212. Therefore, rotating the precision screw can change the length of the screw end face protruding out of the precision screw mounting hole, so that the distance between the one end of the main accommodating part 211 and the secondary accommodating part 212 is changed, and the angle formed by the main accommodating part 211 and the secondary accommodating part 212 is changed, thereby adjusting the center frequency λ of the parallel laser of a specific wavelength range.

[0050] Specifically, refer to Figures 5-7 , Figure 5 The cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range of the application is a structure schematic view of the cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range, Figure 6 The cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range of the application is a side view of the cat-eye tuning structure of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range, Figure 7 The cat-eye tuning structure 3 of the cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range of the application is a sectional view of the cat-eye tuning structure. The cat-eye tuning structure 3 comprises a linear guide rail 31, a piezoelectric ceramic 32, a cat-eye lens mounting seat 33, a cat-eye lens 34, a partial mirror mounting seat 35, a partial mirror 36, a collimating output lens mounting seat 37 and a collimating output lens 38.

[0051] The linear guide rail 31 is mounted inside the cuboid box structure, close to one side of the isolator 4, and is fixedly connected with the bottom of the vacuum system shell 11.

[0052] The piezoelectric ceramic 32 is arranged on the linear guide rail 31 and fixedly connected to the end of the linear guide rail 31 away from the isolator 4. The length of the piezoelectric ceramic 32 is controlled by an external controller.

[0053] The cat-eye lens mount 33 is fixedly connected to the piezoelectric ceramic 32 and arranged on the linear guide rail 31 and capable of sliding relative to the linear guide rail. When the length of the piezoelectric ceramic 32 is changed by the external controller, the length of the cat-eye lens mount 33 away from the end of the linear guide rail 31 away from the isolator 4 also changes. The gap between the cat-eye lens mount 33 and the linear guide rail 31 is provided with a steel ball 311 to reduce the friction when the cat-eye lens mount 33 slides on the linear guide rail 31.

[0054] The cat-eye lens mount 33 comprises a base and a cat-eye lens mounting portion. The bottom of the base is mounted on the linear guide rail 31 and the top is provided with two rows of thread holes arranged at equal intervals. The cat-eye lens mounting portion is arranged perpendicularly to the end of the base away from the isolator 4 and forms an "L" structure together with the base. The cat-eye lens mounting portion is provided with a cat-eye lens mounting port opposite to the narrow-band filter mounting port, and the cat-eye lens 34 is mounted in the cat-eye lens mounting port. In an embodiment, the cat-eye lens is fixed in the cat-eye lens mounting port by epoxy resin; and the thread holes are M2 thread holes. Preferably, the cat-eye lens mount 33 should be as light as possible; when manufacturing the cat-eye lens mount, as much material as possible should be cut off under the premise of ensuring rigidity to achieve light weight, improve the resonance frequency, and thus reduce the influence of low-frequency vibration on the working stability of the semiconductor laser.

[0055] The bottom of the partial mirror mount 35 is provided with a slot hole at each end, and the distance between the two slot holes is equal to the distance between the two rows of thread holes of the base of the cat-eye lens mount. When the two slot holes are aligned with one pair of thread holes of the two rows of thread holes respectively, two screws are passed through a slot hole and a thread hole respectively, and the partial mirror mount 35 can be fixedly mounted on the top of the base of the cat-eye lens mount 33. The partial mirror mount 35 is provided with a partial mirror mounting port opposite to the cat-eye lens mounting port, and the partial mirror is mounted in the partial mirror mounting port. Further, the different reflectivity of the partial mirror will affect the intensity of the optical feedback; the optimal optical feedback intensity can be obtained by comparing the optical feedback intensities of partial mirrors with different reflectivity through testing, so that a partial mirror with appropriate reflectivity can be selected.

[0056] The bottom of the collimating output lens mount 37 is provided with two slot holes, and the distance between the two slot holes is equal to the distance between the two rows of screw holes in the base of the cat-eye lens mount 33. When the two slot holes are respectively aligned with one pair of screw holes in the two rows of screw holes, two screws are respectively inserted through a slot hole and a screw hole, and the collimating output lens mount 37 is fixedly installed on the top of the base of the cat-eye lens mount 33. The collimating output lens mount 37 is provided with a collimating output lens mount hole opposite to the partial mirror mount hole, and the collimating output lens 38 is installed in the collimating output lens mount hole.

[0057] By aligning the slot holes of the partial mirror mount 35 with different screw holes, aligning the slot holes of the collimating output lens mount 37 with different screw holes, and fine-tuning the relative positions of each pair of slot holes and specific screw holes, the partial mirror 36 is located exactly on the focal planes of the cat-eye lens 34 and the collimating output lens 38. After the partial mirror mount and the collimating output lens are fixed by screws, the relative positions of the cat-eye lens 34, the partial mirror 36, and the collimating output lens 38 are fixed, and no matter how the length of the piezoelectric ceramic 32 changes or how the cat-eye lens mount 33 slides on the linear guide rail 31, the partial mirror 36 is located exactly on the focal planes of the cat-eye lens 34 and the collimating output lens 38.

[0058] Please refer to Figure 8 , Figure 8The figure is a schematic diagram of the optical path of the cat-eye external cavity semiconductor laser. The laser diode 22, collimating lens 24, narrow-band filter 26, cat-eye lens 34, partial mirror 36, collimating output lens 38 are arranged in sequence on the same optical path. The laser diode 22 emits dispersed light; the collimating lens 24 collimates and shapes the dispersed light emitted by the laser diode 22 into parallel light; the narrow-band filter 26 selects the frequency of the parallel light and converts it into parallel laser light of a specific wavelength range. The cat-eye lens 34 converges the parallel laser light of the specific wavelength range and converts it into convergent laser light of a specific wavelength range, with the focal point located on the partial mirror 36. The partial mirror 36 reflects part of the convergent laser light of the specific wavelength range, and the reflected convergent laser light returns to the laser diode 22 along the original optical path and resonates with the dispersed light emitted by the laser diode 22. The space between the laser diode 22, collimating lens 24, narrow-band filter 26, cat-eye lens 34, and partial mirror 36 forms a resonant cavity, and the length of the resonant cavity determines the specific frequency of the output laser light. The other part of the convergent laser light that is not reflected passes through the partial mirror 36 and enters the collimating output lens 38. The collimating output lens collimates and shapes the convergent laser light and converts it into parallel laser light of a specific frequency, which is output through the light output window to the isolator 4.

[0059] In use, the partial mirror mounting seat 35 and the collimating output lens mounting seat 37 are fixed to the cat-eye lens mounting seat 33 by screws, so that the partial mirror 36 is located exactly on the focal plane of the cat-eye lens 34 and the collimating output lens 38; the central frequency of the parallel laser light of a specific wavelength range is adjusted by rotating the precision screw 27; the specific frequency of the output parallel laser light is adjusted by adjusting the length of the piezoelectric ceramic 32. Since the external controller can send an electrical signal to control the length of the piezoelectric ceramic 32 and the rotation of the electric actuator, after the partial mirror mounting seat 35 and the collimating output lens mounting seat 37 are installed, the user can complete the tuning of the frequency of the laser light output by the cat-eye external cavity semiconductor laser by operating the external controller.

[0060] The existing tunable cat-eye external cavity semiconductor laser generally adjusts the resonant cavity length by adjusting the position of the partial mirror, which causes the cat-eye structure to be destroyed during tuning, and further causes the feedback light intensity of the cat-eye semiconductor laser to change, and finally causes the mode jumping and other unstable problems. The partial mirror mounting seat and the collimating output lens mounting seat are fixedly installed on the cat-eye lens mounting seat, the cavity length is adjusted by adjusting the position of the cat-eye lens mounting seat, and the mode jumping, output light intensity jitter and other unstable problems of the laser caused by directly adjusting the position of the partial mirror are avoided. Further, the application also sets up a vacuum system and an isolator to isolate the influence of external air, external temperature and humidity changes and external light on the laser, and further improves the working stability of the laser. Further, the application integrally connects the sub-housing part for installing the narrow-band filter and the main housing part for installing the laser diode and the collimating filter, which on the one hand improves the compactness of the design and miniaturizes the laser, and on the other hand avoids the position or angle deviation of the narrow-band filter caused by machining error or installation error.

[0061] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, and the present application also intends to include these modifications and improvements.

Claims

1. A cat-eye external cavity semiconductor laser with wide scanning range without mode hopping, comprising: a laser collimation filter structure for emitting parallel laser light of a specific wavelength range; and a cat-eye tuning structure for tuning the parallel laser light emitted by the laser collimation filter structure to output parallel laser light of a specific frequency. The cat-eye tuning structure comprises: a linear guide, a piezoelectric ceramic, a cat-eye lens mount, a cat-eye lens, a partial mirror, and a collimation output lens; the piezoelectric ceramic and the cat-eye lens mount are both mounted on the linear guide; the cat-eye lens mount is fixed to one end of the linear guide via the piezoelectric ceramic; the relative positions of the cat-eye lens, the partial mirror, and the collimation output lens are fixed, and they are all mounted on the cat-eye lens mount; the cat-eye lens converges the parallel laser light of the specific wavelength range, and the focal point is located on the partial mirror; the length of the piezoelectric ceramic changes, causing the cat-eye lens mount to slide relative to the linear guide, and thus causing the distance between the partial mirror and the laser collimation filter structure to change to obtain parallel laser light of a specific frequency. The collimation output lens collects and shapes the convergent laser light that passes through the partial mirror to output parallel laser light of a specific frequency.

2. The cat-eye external cavity semiconductor laser with wide scanning range without mode hopping according to claim 1, wherein: The laser collimation filter structure comprises: a laser housing, a laser diode, a collimation lens, and a narrowband filter; the laser housing comprises: a main accommodating portion, a secondary accommodating portion, and a C-shaped connecting portion; One end of the main accommodating portion and the secondary accommodating portion are fixedly connected via the C-shaped connecting portion, and the other end is separated; the laser diode and the collimation lens are mounted in the main accommodating portion, and the narrowband filter is mounted in the secondary accommodating portion; The laser diode emits dispersed light; the collimation lens collects and shapes the dispersed light emitted by the laser diode into parallel light; and the narrowband filter selects the frequency of the parallel light to convert it into parallel laser light of a specific wavelength range; By changing the angle formed by the main accommodating portion and the secondary accommodating portion, the incident angle of the parallel light entering the narrowband filter can be changed, and thus the center frequency of the parallel laser light of a specific wavelength range can be changed.

3. The cat-eye external cavity semiconductor laser with wide scanning range without mode hopping according to claim 2, wherein: The laser collimation filter structure further comprises: a precision screw; the main accommodating portion is further provided with a precision screw mounting hole; and the precision screw is mounted in the precision screw mounting hole, with its screw end face extending out of the precision screw mounting hole to abut against the secondary accommodating portion.

4. The cat-eye external cavity semiconductor laser with wide scanning range without mode hopping according to claim 3, wherein: ​ The laser collimation filter structure further comprises: a laser diode snap ring provided with a pin positioning hole; a side of the main accommodating portion away from the auxiliary accommodating portion is provided with a laser diode mounting hole; the laser diode snap ring is fixedly installed in the laser diode mounting hole; the laser diode comprises a lamp bead and a pin; wherein the lamp bead is located inside the main accommodating portion, and the pin extends out of the main accommodating portion through the pin positioning hole of the laser diode snap ring.

5. The cat-eye external cavity semiconductor laser with wide non-jump mode scanning range according to claim 4, wherein: The laser collimation filter structure further comprises: an O-ring; the collimation lens is installed in one side of the main accommodating portion close to the auxiliary accommodating portion, and is installed in the main accommodating portion through the internal thread provided in the main accommodating portion; the O-ring is fixedly sleeved on the outer periphery of the collimation lens, and fills the gap between the collimation lens and the internal thread in the main accommodating portion for fixing the collimation lens.

6. The cat-eye external cavity semiconductor laser with wide non-jump mode scanning range according to claim 1, wherein: Further comprising a vacuum system, the vacuum system comprising: a vacuum system shell, a vacuum system cover, a window lens; The vacuum system shell is a long rectangular box-shaped structure with an open top; the vacuum system cover is arranged on the top of the long rectangular box-shaped structure to form a closed long rectangular box-shaped structure together with the vacuum system shell; the laser collimation filter structure and the cat-eye tuning structure are installed inside the long rectangular box-shaped structure; the front of the long rectangular box-shaped structure is provided with a light outlet window; the window lens is fixedly installed in the light outlet window.

7. The cat-eye external cavity semiconductor laser with wide non-jump mode scanning range according to claim 6, wherein: The vacuum system further comprises: an angle valve and a small ion pump; One side of the long rectangular box-shaped structure is provided with an angle valve mounting hole; the angle valve is provided with a top outlet, a bottom outlet and a side outlet; the top outlet of the angle valve is in butt joint with the angle valve mounting hole; the side outlet is connected with the small ion pump; the bottom outlet is connected with an external vacuum pump during vacuumizing, and is sealed after vacuumizing is completed; during vacuumizing, the bottom outlet of the angle valve is opened, and the pump head of the vacuum pump is connected with the bottom outlet for vacuumizing treatment; after vacuumizing is completed, the pump head of the vacuum pump is pulled out, and the bottom outlet is sealed, and the small ion pump is started.

8. The cat-eye external cavity semiconductor laser with wide non-jump mode scanning range according to claim 7, wherein: The vacuum system further comprises: a semiconductor refrigerating sheet; the upper and lower surfaces of the semiconductor refrigerating sheet are smeared with heat-conducting silicone grease; the lower surface contacts the bottom of the vacuum system shell, and the upper surface contacts the laser collimation filter structure; the semiconductor refrigerating sheet provides heating or cooling effect according to the temperature detected by the thermistor arranged inside the laser collimation filter structure, so as to maintain the temperature of the vacuum system and the laser collimation filter structure.

9. The cat-eye external cavity semiconductor laser with wide non-jump mode scanning range according to claim 8, wherein: Also includes an isolator for preventing external light into the laser inside; the bottom of the front of the cuboid box structure, extending out the isolator mounting plate; the isolator is installed on the isolator mounting plate; the laser of the specific frequency can be transmitted through the window lens into the isolator.

10. The cat-eye external cavity semiconductor laser with wide mode-hop-free scanning range according to claim 9, wherein: The cat-eye tuning structure further comprises a partial mirror mounting seat and a collimating output lens mounting seat; the cat-eye lens mounting seat comprises a base and a cat-eye lens mounting portion; The bottom of the base is mounted on the linear guide rail, and the top is provided with two rows of equidistantly arranged threaded holes; the cat-eye lens mounting portion is vertically arranged at the end of the base away from the isolator, and forms an "L" type structure together with the base; the cat-eye lens mounting portion is provided with a cat-eye lens mounting opening, and the cat-eye lens is mounted in the cat-eye lens mounting opening; The bottom of the partial mirror mounting seat is provided with a slot hole at each end, and the distance between the two slot holes is equal to the distance between the two rows of threaded holes of the base of the cat-eye lens mounting seat; when the two slot holes are aligned with one pair of threaded holes of the two rows of threaded holes respectively, two screws are passed through a slot hole and a threaded hole respectively to fix the partial mirror mounting seat on the top of the base of the cat-eye lens mounting seat; the partial mirror mounting seat is provided with a partial mirror mounting opening opposite to the cat-eye lens mounting opening, and the partial mirror is mounted in the partial mirror mounting opening; The bottom of the collimating output lens mounting seat is provided with a slot hole at each end, and the distance between the two slot holes is equal to the distance between the two rows of threaded holes of the base of the cat-eye lens mounting seat; when the two slot holes are aligned with one pair of threaded holes of the two rows of threaded holes respectively, two screws are passed through a slot hole and a threaded hole respectively to fix the collimating output lens mounting seat on the top of the base of the cat-eye lens mounting seat; the collimating output lens mounting seat is provided with a collimating output lens mounting opening opposite to the partial mirror mounting opening, and the collimating output lens is mounted in the collimating output lens mounting opening.

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