High-order laser intracavity generating device

Abstract

The invention relates to a high-order laser intracavity generating device which comprises an output assembly used for outputting effective pumping laser, a resonant cavity arranged on one side of the pumping laser output assembly and a gain medium arranged between an input mirror and an output mirror in the resonant cavity, and the gain medium is used for generating fluorescence in the range of 650-850 nm under pumping of the effective pumping laser. A target defect is etched on the output mirror, one part of the fluorescence is output through the target defect position, and the other part of the fluorescence meeting the high-order laser light field distribution is reflected at the non-defect position on the output mirror, is amplified again through the gain medium and oscillates between the input mirror and the output mirror to form high-order laser, and then the high-order laser is output through the output mirror; wherein the high-order laser is Hermitian laser or high-order vortex laser; according to the invention, the oscillation mode of the resonant cavity and the wavelength of the laser can be adjusted, and high-order Hermitian laser or high-order vortex laser with a specific wavelength can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of lasers, and particularly to a high-order laser intracavity generation device. Background Art

[0002] Hermite-Gaussian lasers and vortex lasers with wavelengths in the range of 750 - 785 nm have important application values in laser medicine, optical tweezers, laser pumping, cold atoms, hot atoms, etc. Currently, the methods for generating Hermite-Gaussian lasers and vortex lasers with wavelengths in the range of 750 - 785 nm mainly convert the fundamental-mode Gaussian laser with the target wavelength generated by a semiconductor laser into high-order Hermite-Gaussian lasers and vortex lasers through an extracavity generation method. Among them, the wavelength tuning method mainly locks the wavelength through a grating. However, the method of locking the wavelength by a grating has poor stability and is prone to wavelength drift under the influence of thermal effects.

[0003] Currently, the methods for generating Hermite-Gaussian lasers and vortex lasers can be divided into extracavity generation methods and intracavity generation methods. Among them, the extracavity generation method modulates an ordinary fundamental-mode Gaussian beam through modulation elements such as a phase plate, so that the fundamental-mode beam generates a specific phase delay in different orientations, and then changes the phase distribution of the fundamental-mode Gaussian beam to realize the conversion of the fundamental-mode Gaussian beam into a Hermite-Gaussian beam. However, the damage thresholds of mode conversion elements such as phase plates and spatial light modulators in this method are relatively low, which have strict restrictions on the laser power density. It is difficult to generate high-power Hermite-Gaussian lasers or vortex lasers, and the Hermite-Gaussian lasers or vortex lasers generated by modulation through this method are quasi-continuous in phase, difficult to achieve high purity, and cannot be propagated over a long distance in space. The methods for generating vortex lasers by intracavity generation mainly include the ring optical pumping method, the point defect etched cavity mirror method, and the tilted pumping method. These methods, on the one hand, block the pumping efficiency of the pump laser to the gain medium, and on the other hand, these methods can only be used to generate vortex lasers and cannot generate high-order Hermite-Gaussian lasers.

[0004] In summary, there is currently a lack of a 750 - 785 nm high-order Hermite-Gaussian laser and vortex laser light source with high power, good beam quality, stable propagation, and simple structure. Solving this problem is of great significance to fields such as atomic cooling, heating, optical super-resolution microscopy, and optical tweezers, and can promote the further development of related fields. Summary of the Invention

[0005] In view of the deficiencies in the background art, the present invention provides a high-order laser intracavity generation device, including: a pump laser output component, a resonant cavity, and a gain medium. The pump laser output component is used to output effective pump laser, and the effective pump laser is a focused pump laser with a wavelength of 638 nm and transverse polarization.

[0006] The resonant cavity is arranged on one side of the pump laser output component. The resonant cavity includes an input mirror and an output mirror that are relatively spaced apart. The input mirror is arranged between the output mirror and the pump laser output component, and the input mirror is used to transmit the effective pump laser into the resonant cavity;

[0007] The gain medium is arranged between the input mirror and the output mirror. The gain medium is used to generate fluorescence under the pumping of the effective pump laser, and the wavelength range of the fluorescence is 650nm - 850nm;

[0008] A target defect is etched on the output mirror. A part of the fluorescence is output through the target defect position, and another part of the fluorescence that satisfies the high - order laser light field distribution is reflected at the non - defect position on the output mirror, and then amplified again through the gain medium and oscillates between the input mirror and the output mirror to form a high - order laser with a target wavelength and is output through the output mirror. Among them, the high - order laser is a high - order Hermite - Gaussian laser or a high - order vortex laser. When generating the high - order Hermite - Gaussian laser or the high - order vortex laser, different defect shapes are used as the target defect respectively. The first target wavelength and the second target wavelength are the same or different. The wavelength of the first target wavelength is one of 750nm - 785nm, and the wavelength of the second target wavelength is one of 750nm - 785nm.

[0009] Further, the device is also provided with an etalon. The etalon is arranged between the gain medium and the output mirror. When the tilt angle of the etalon is adjusted, the first target wavelength of the high - order Hermite - Gaussian laser output by the output mirror is changed, or the second target wavelength of the high - order vortex laser output by the output mirror is changed.

[0010] Further, the pump laser output component includes a semiconductor pump laser, a shaping optical fiber, an optical fiber output head, a pump laser collimating mirror and a pump laser focusing mirror; the semiconductor pump laser is a 638nm semiconductor laser. The pump laser with a wavelength of 638nm generated by the semiconductor pump laser is shaped by the shaping optical fiber and then output by the optical fiber output head. The pump laser is collimated by the pump laser collimating mirror into collimated pump laser. The collimated pump laser includes horizontally polarized collimated pump laser and vertically polarized collimated pump laser, and the horizontally polarized collimated pump laser constitutes the effective pump laser.

[0011] Further, a polarization beam splitter prism and a beam terminator are further included in the pump laser output assembly. The beam terminator is disposed on one side of the polarization beam splitter prism. The polarization beam splitter prism splits the transversely polarized collimated laser and the longitudinally polarized collimated laser. The transversely polarized collimated laser after beam splitting is incident on the pump laser focusing mirror, and after being focused, is incident on the resonant cavity. The longitudinally polarized collimated laser after beam splitting undergoes a 90° refraction and enters the beam terminator.

[0012] Further, the gain medium is chrysoberyl, and the chrysoberyl is placed in a copper heat sink cooling system.

[0013] Further, the device further includes a filter. The filter is coated with a first film system. The high-order Hermite-Gaussian laser or the high-order vortex laser can pass through the first film system, and the effective pump laser is reflected by the first film system.

[0014] Further, the target defect widths and shapes etched on the output mirror are different.

[0015] Further, the device is a basic film laser, including a pump laser output assembly, a resonant cavity, a gain medium, and a etalon; the pump laser output assembly is used to output an effective pump laser, and the effective pump laser is a transversely polarized collimated pump laser with a wavelength of 638 nm;

[0016] The resonant cavity is disposed on one side of the pump laser output assembly. The resonant cavity includes an input mirror and an output mirror that are relatively spaced apart. The input mirror is disposed between the output mirror and the pump laser output assembly. The input mirror is used to transmit the effective pump laser into the resonant cavity;

[0017] The gain medium is disposed between the input mirror and the output mirror. The gain medium is used to generate fluorescence under the pumping of the effective pump laser, and the wavelength range of the fluorescence is 650 nm - 850 nm;

[0018] The etalon is disposed between the gain medium and the output mirror. When the tilt angle of the etalon is adjusted, the wavelength of the high-order Hermite-Gaussian laser output by the output mirror is changed, or the wavelength of the high-order vortex laser output by the output mirror is changed.

[0019] The intracavity generation device of a high-order laser provided by the present invention includes but is not limited to the following beneficial effects: (1) In this technical solution, by using chrysoberyl as the gain medium, chrysoberyl has an ultra-wide absorption spectrum. Based on the absorption characteristics of chrysoberyl for the 638-nm wavelength laser, fluorescence in an ultra-wide range can be obtained, and lasers in a specific wavelength range can be obtained through the resonator and wavelength tuning to meet the user's requirements for specific wavelengths; (2) By etching target defects with different shapes on the output mirror, the oscillation mode of the resonator is adjusted to obtain high-order Hermite-Gaussian lasers or high-order vortex lasers with specific modes; (3) The wavelength of the pump laser is close to that of the target laser, improving the quantum conversion efficiency of the pump laser; and the pump laser is shaped through an optical fiber, a polarization beam splitter prism, a pump laser collimating mirror, and a pump laser focusing mirror to obtain high-quality pump laser, improving the overall pump efficiency of the laser; (4) The output mirror etching method avoids the loss of the pump laser, improving the efficiency of the pump laser, and the intracavity generation method uses the self-organization characteristics of light to improve the purity of high-order Hermite-Gaussian lasers and high-order vortex lasers; (5) The entire device has a simple and compact structure, facilitating integration and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art.

[0021] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present invention;

[0022] Figure 2 It is a schematic structural diagram of Embodiment 2 of the present invention;

[0023] Figure 3 It is a schematic diagram of the etalon adjustment direction in Embodiment 2 of the present invention;

[0024] Figure 4 It is a schematic diagram of the etalon tuning wavelength principle in Embodiment 2 of the present invention;

[0025] Figure 5 It is the fluorescence spectrum of the chrysoberyl used in Embodiment 1 and Embodiment 2 of the present invention;

[0026] Figure 6 It is a schematic diagram of the wavelength tuning result in Embodiment 1 of the present invention;

[0027] Figure 7 It is a schematic diagram of the etching situation and the obtained Hermite-Gaussian laser and vortex laser in Embodiment 1 of the present invention;

[0028] In the figure, 1 is a pump laser output component, 11 is a semiconductor pump laser, 12 is a shaping optical fiber, 13 is an optical fiber output head, 14 is a pump laser collimating mirror, 15 is a pump laser focusing mirror, 16 is a polarization beam splitter prism, and 17 is a beam terminator; 2 is a resonant cavity, 21 is an input mirror, and 22 is an output mirror; 3 is a gain medium, 4 is an etalon, and 5 is a filter. Specific embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

[0030] This application provides a high-order laser intracavity generation device. Referring to Figure 1 , it includes: a pump laser output component 1, a resonant cavity 2, and a gain medium 3. The pump laser output component 1 is used to output effective pump laser, and the effective pump laser is a focused pump laser with a transverse polarization of 638 nm wavelength; the resonant cavity 2 is arranged on one side of the pump laser output component 1. The resonant cavity 2 includes an input mirror 21 and an output mirror 22 arranged at a relatively spaced interval. The input mirror 21 is arranged between the output mirror 22 and the pump laser output component 1; the gain medium 3 is arranged between the input mirror 21 and the output mirror 22. The effective pump laser, that is, the focused pump laser with a transverse polarization of 638 nm wavelength, passes through the input mirror 21 and is transmitted into the resonant cavity 2 and then incident on the gain medium 3. The gain medium 3 generates fluorescence with a wavelength range of 650 nm - 850 nm under the pumping of the effective pump laser; different-shaped target defects are etched on the output mirror 22. A part of the fluorescence is output through the target defect position, and another part of the fluorescence that satisfies the high-order laser light field distribution is reflected at the non-defect position on the output mirror 22, amplified again through the gain medium, and oscillates between the input mirror 21 and the output mirror 22 to form high-order laser of the target wavelength and then is output through the output mirror 22. Among them, the high-order laser is a high-order Hermite-Gaussian laser or a high-order vortex laser. When generating a high-order Hermite-Gaussian laser or a high-order vortex laser, different defect shapes are used as the target defects respectively. The first target wavelength and the second target wavelength are the same or different, and both the first target wavelength and the second target wavelength fall within the range of 750 nm - 785 nm.

[0031] By etching different-shaped defects on the output mirror 22, the oscillation mode of the resonant cavity is adjusted, and high-order Hermite-Gaussian laser or high-order vortex laser of a specific wavelength is obtained;

[0032] In a preferred embodiment, the input mirror 21 is a flat mirror, and a second film system is deposited on the input mirror 21. The transmittance of the second film system for the effective pump laser with a wavelength of 638 nm is > 99.5%. This high transmittance enables the effective pump laser to act more effectively on the gain medium 3, thereby improving the generation efficiency of high-order Hermite-Gaussian lasers or high-order vortex lasers. Moreover, the reflectance of the second film system for the fluorescence in the range of 750 - 785 nm is > 99.5%. This high reflectance helps to establish a stable oscillation mode in the resonator 2, improves the quality and stability of the obtained high-order Hermite-Gaussian lasers or high-order vortex lasers. At the same time, this high reflectance reduces the energy loss in the cavity, allowing more fluorescence to participate in the process of oscillation to form laser. The output mirror 22 is also a flat mirror. The defects etched on the output mirror 22 can be stripes with different widths and shapes or circles with different sizes. The transmittance of the non-etched defect position of the output mirror 22 for the fluorescence in the range of 750 - 785 nm is 5%, which helps to reduce the unnecessary loss of pump fluorescence in the cavity, enabling more fluorescence with the light field distribution located at the non-etched defect position to participate in the process of oscillation to form laser. The transmittance of the target defect position on the output mirror 22 for the laser with a wavelength of 750 - 785 nm is greater than 80%, meaning that most of the laser energy with the light field distribution located at the defect position can be output through the target defect position. Since the high-order Hermite-Gaussian or high-order vortex lasers with specific modes correspond to different light field distributions, adjusting the losses of different light field distributions is beneficial to the output of high-order Hermite-Gaussian or high-order vortex lasers with specific modes.

[0033] Furthermore, referring to Figure 2 、 Figure 3 , the device is also provided with an etalon 4. The etalon 4 is arranged between the gain medium 3 and the output mirror 22. By changing the tilt angle of the etalon 4, the effective cavity length can be precisely controlled, and then the resonance wavelength can be changed. Therefore, it is possible to selectively enhance or suppress the light of a specific wavelength, realizing the selection and tuning of the wavelength.

[0034] Further, the pump laser output assembly 1 includes a semiconductor pump laser 11, a shaping optical fiber 12, an optical fiber output head 13, a pump laser collimating mirror 14, and a pump laser focusing mirror 15; the semiconductor pump laser 11 is a 638 nm semiconductor laser, and the pump laser with a wavelength of 638 nm generated by the semiconductor pump laser 11 is shaped by the shaping optical fiber 12 and then output by the optical fiber output head 13. The pump laser is collimated by the pump laser collimating mirror 14 into a collimated pump laser, and the collimated pump laser includes a transversely polarized collimated pump laser and a longitudinally polarized collimated pump laser, and the transversely polarized collimated pump laser constitutes the effective pump laser; by providing the shaping optical fiber 12 for adjusting the beam shape of the output of the semiconductor pump laser 11, the uniformity and consistency of the beam are ensured, the quality of the pump laser beam is improved, and thus the pump efficiency is improved. Preferably, the core diameter of the shaping optical fiber is 200 μm, the numerical aperture is 0.22, and the focal length of the pump laser collimating mirror is 100 mm.

[0035] Further, the pump laser output assembly 1 further includes a polarization beam splitter prism 16 and a beam terminator 17. The beam terminator 17 is disposed on one side of the polarization beam splitter prism 16. The polarization beam splitter prism 16 splits the transversely polarized collimated laser and the longitudinally polarized collimated laser. The transversely polarized collimated laser after splitting is incident on the pump laser focusing mirror 15, and after focusing, it is incident on the resonator 2. The longitudinally polarized collimated laser after splitting is reflected by 90° and incident on the beam terminator 17. According to the characteristics of the polarization absorption of the Alexandrite crystal pair for the transverse pump laser, the polarization beam splitter prism 16 is provided to screen out the effective pump laser, reducing the influence of stray light such as the longitudinally polarized collimated laser; preferably, the focal length of the pump laser focusing mirror 15 is 50 mm, and the spot diameter of the focused effective pump laser is 100 μm.

[0036] Further, the gain medium 3 is an Alexandrite crystal. Preferably, to prevent overheating damage, the Alexandrite is wrapped with indium foil and placed in a copper heat sink cooling system cooled by circulating water. The fluorescence spectrum of the Alexandrite 3 under the excitation of 638 nm laser is as Figure 5 shown, and the spectral range is 650 nm - 850 nm.

[0037] Further, the device further includes a filter 5. The filter is coated with a first film system. The transmittance of the first film system for higher-order Hermite-Gaussian laser or higher-order vortex laser is greater than 99.5%, while the transmittance for the 638 nm pump laser is less than 0.5%, that is, the higher-order Hermite-Gaussian laser or higher-order vortex laser can pass through, while the effective pump laser is almost completely reflected; by providing the filter 5, the effective pump laser and other stray light can be filtered out to obtain higher-purity higher-order Hermite-Gaussian laser or vortex laser.

[0038] In another preferred embodiment, the device is configured as a fundamental mode laser, including a pump laser output component 1, a resonant cavity 2, a gain medium 3, and a etalon 4; the pump laser output component 1 is used to output effective pump laser, and the effective pump laser is a focused pump laser with a transverse polarization and a wavelength of 638 nm;

[0039] The resonant cavity 2 is arranged on one side of the pump laser output component 1. The resonant cavity 2 includes an input mirror 21 and an output mirror 22 which are relatively spaced apart. The input mirror 21 is arranged between the output mirror 22 and the pump laser output component 1. The input mirror 21 is used to transmit the effective pump laser into the resonant cavity 2, and no defects are etched on the output mirror 22;

[0040] The gain medium 3 is arranged between the input mirror 21 and the output mirror 22. The gain medium 3 is used to generate fluorescence under the pumping of the effective pump laser, and the wavelength range of the fluorescence is 650 nm - 850 nm;

[0041] The etalon 4 is arranged between the gain medium 3 and the output mirror 22. When the tilt angle of the etalon 4 is adjusted, the wavelength of the high-order Hermite-Gaussian laser output by the output mirror 22 is changed, or the wavelength of the high-order vortex laser output by the output mirror 22 is changed;

[0042] By not etching defects on the output mirror 22, the loss in the cavity is reduced, thereby improving the overall efficiency and output power of the fundamental mode laser.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0044] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A high-order laser intracavity generation device, characterized in that: include: A pump laser output component (1), a resonant cavity (2) and a gain medium (3), wherein the pump laser output component (1) is used to output an effective pump laser, wherein the effective pump laser is a transversely polarized collimated pump laser with a wavelength of 638 nm; The resonant cavity (2) is arranged at one side of the pump laser output component (1), the resonant cavity (2) comprises an input mirror (21) and an output mirror (22) which are arranged relatively spaced apart, the input mirror (21) is arranged between the output mirror (22) and the pump laser output component (1), and the input mirror (21) is used to transmit the effective pump laser into the resonant cavity (2); The gain medium (3) is arranged between the input mirror (21) and the output mirror (22), and the gain medium (3) is used to generate fluorescence under the pumping of the effective pump laser, and the wavelength range of the fluorescence is 650nm-850nm; A target defect is etched on the output mirror (22), a portion of the fluorescence is output through the target defect position, and another portion of the fluorescence that satisfies the high-order laser light field distribution is reflected at a non-defect position on the output mirror (22), is amplified again by the gain medium, and oscillates between the input mirror (21) and the output mirror (22) to form a high-order laser of a target wavelength, which is then output through the output mirror, wherein the high-order laser is a high-order Hermite Gaussian laser or a high-order vortex laser. When the high-order Hermite Gaussian laser or the high-order vortex laser is generated, different defect shapes are used as target defects, and the target wavelength is one of 750nm-785nm.

2. The high-order laser intracavity generating device according to claim 1, characterized in that: The device is further provided with an etalon (4), wherein the etalon (4) is arranged between the gain medium (3) and the output mirror (22), and when the tilt angle of the etalon (4) is adjusted, the first target wavelength of the high-order Hermite-Gaussian laser output by the output mirror (22) is changed, or the second target wavelength of the high-order vortex laser output by the output mirror (22) is changed.

3. The high-order laser intracavity generating device according to claim 2, characterized in that: The pump laser output component (1) comprises a semiconductor pump laser (11), a shaping optical fiber (12), an optical fiber output head (13), a pump laser collimator (14) and a pump laser focusing lens (15); the semiconductor pump laser (11) is a 638 nm semiconductor laser; the pump laser with a wavelength of 638 nm generated by the semiconductor pump laser (11) is shaped by the shaping optical fiber (12) and then output by the optical fiber output head (13); the pump laser is collimated by the pump laser collimator (14) to become a collimated pump laser; the collimated pump laser comprises a transversely polarized collimated pump laser and a longitudinally polarized collimated pump laser; the transversely polarized collimated pump laser is the effective pump laser.

4. The high-order laser intracavity generating device according to claim 3, characterized in that: The pump laser output assembly (1) further comprises a polarization beam splitter prism (16) and a beam terminator (17). The beam terminator (17) is arranged on one side of the polarization beam splitter prism (16). The polarization beam splitter prism (16) splits the transverse polarization collimated laser and the longitudinal polarization collimated laser. The transverse polarization collimated laser after beam splitting is incident on the pump laser focusing mirror (15) and then incident on the resonant cavity (2) after being focused. The longitudinal polarization collimated laser after beam splitting is reflected at 90° and incident on the beam terminator (17).

5. The high-order laser intracavity generating device according to claim 4, characterized in that: The gain medium (3) is chrysoberyl, which is wrapped by indium foil and placed in a copper heat sink cooling system.

6. The high-order laser intracavity generating device according to claim 5, characterized in that: The device further comprises a filter (5), wherein the filter (5) is coated with a first film system, the high-order Hermite-Gauss laser or the high-order vortex laser can pass through the first film system, and the effective pump laser is reflected by the first film system.

7. The high-order laser intracavity generating device according to claim 6, characterized in that: The target defects etched on the output mirror (22) have different widths and shapes.

8. The high-order laser intracavity generating device according to claim 1, characterized in that: The device comprises a pump laser output component (1), a resonant cavity (2), a gain medium (3) and an etalon (4); the pump laser output component (1) is used to output an effective pump laser, and the effective pump laser is a transversely polarized collimated pump laser with a wavelength of 638 nm; The resonant cavity (2) is arranged at one side of the pump laser output component (1), the resonant cavity (2) comprises an input mirror (21) and an output mirror (22) which are arranged relatively spaced apart, the input mirror (21) is arranged between the output mirror (22) and the pump laser output component (1), and the input mirror (21) is used to transmit the effective pump laser into the resonant cavity (2); The gain medium (3) is arranged between the input mirror (21) and the output mirror (22), and the gain medium (3) is used to generate fluorescence under the pumping of the effective pump laser, and the wavelength range of the fluorescence is 650nm-850nm; The etalon (4) is arranged between the gain medium (3) and the output mirror (22). When the tilt angle of the etalon (4) is adjusted, the wavelength of the high-order Hermite-Gaussian laser output by the output mirror (22) is changed, or the wavelength of the high-order vortex laser output by the output mirror (22) is changed.

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