Multi-wavelength visible light laser based on single gain medium and separate polarization control

Abstract

The embodiments of the present disclosure disclose a multi-wavelength visible light laser based on a single gain medium and polarization control. A specific implementation of the laser includes: a pump part, an integrated gain reflector, a polarization control device, and multiple visible light wavelength generating components. The integrated gain reflector performs broadband reflection of different fundamental wavelengths on the laser wavelength emitted by the pump part, and emits a multi-wavelength laser beam with different fundamental wavelengths, including a substrate, an integrated broadband reflector, a multi-wavelength fundamental frequency light emission area, a chip protection layer, and an excitation light wavelength anti-reflection layer. The polarization control device separates the fundamental frequency lights of different wavelengths by polarization state. Multiple visible light wavelength generating components perform frequency conversion on specific fundamental frequency lights of different polarization states, and finally obtain visible light outputs of different wavelengths. This implementation is related to the field of laser technology, and multi-wavelength visible light output is obtained based on a single gain medium. The device has high integration, strong comprehensiveness, and is easy to carry.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of laser technology, and in particular to a multi-wavelength visible light laser based on a single gain medium and separately controlled polarization. Background Art

[0002] Lasers in the visible light band can be sensed by the human eye and are widely used in laser display, laser lighting and other fields. In addition, lasers in the visible light band can also be absorbed by most of the human body's active tissues, and are extremely valuable in many life science fields such as laser diagnosis, laser beauty, laser medical treatment, gene sequencing, DNA (DeoxyriboNucleic Acid) detection, etc. Lasers in the visible light band can also be absorbed by many ions or atoms and molecules, so they also have good application prospects in laser spectroscopy.

[0003] However, currently there are very limited methods for obtaining visible light lasers. For example, a small number of visible light lasers can be obtained from liquid or gas gain media, such as dye lasers, or gas lasers such as argon ion, helium neon, etc. Blue, green and red visible light lasers can also be obtained from semiconductor laser diodes. A small number of visible light lasers can also be obtained from solid lasers through nonlinear frequency conversion such as frequency doubling or parametric oscillation. These methods of obtaining visible light lasers all have some disadvantages and cannot meet the needs of actual scenarios.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0005] The content of this disclosure is used to introduce concepts in a brief form, which will be described in detail in the detailed implementation section below. The content of this disclosure is not intended to identify the key features or essential features of the technical solution claimed for protection, nor is it intended to limit the scope of the technical solution claimed for protection.

[0006] Some embodiments of the present disclosure propose a multi-wavelength visible light laser based on a single gain medium and polarization control, comprising: a pumping part, including an excitation light source, for emitting a laser wavelength; an integrated gain reflector, for performing broadband reflection of different fundamental wavelengths on the laser wavelength emitted by the pumping part, and emitting a multi-wavelength laser beam with different fundamental wavelengths, comprising a substrate and an integrated broadband reflector, a multi-wavelength fundamental frequency light emitting region, a chip protection layer, and an excitation light wavelength anti-reflection layer fixed on the substrate in sequence; a polarization control device, for separating the multi-wavelength laser beam emitted by the integrated gain reflector by polarization state to obtain a plurality of laser beams with different polarization fundamental frequency wavelengths, the polarization control device being coated with a film layer with high transmittance to polarization fundamental frequency wavelength 1 and high reflectance to polarization fundamental frequency wavelength 2 on an incident surface, and being coated with a film layer with high transmittance to polarization fundamental frequency wavelength 1 on an exit surface; a plurality of visible light wavelength generating components, for performing frequency conversion on laser beams with different polarization fundamental frequency wavelengths output by the polarization control device, and outputting laser beams with different visible light wavelengths, comprising a polarization phase matching nonlinear element and a visible light wavelength output mirror.

[0007] In some embodiments, the integrated broadband reflector is composed of two refractive layers with different refractive indices alternatingly to provide broadband reflectivity including fundamental wavelength one and fundamental wavelength two; the multi-wavelength fundamental frequency light emission zone includes: fundamental wavelength one emission layer, excitation light absorption layer one, fundamental wavelength two emission layer, excitation light absorption layer two; wherein, the fundamental wavelength one emission layer and the excitation light absorption layer one are alternately arranged to constitute a first emission zone, and the fundamental wavelength two emission layer and the excitation light absorption layer two are alternately arranged to constitute a second emission zone.

[0008] In some embodiments, the first emission region is located between the integrated broadband reflector and the second emission region; the components of the excitation light absorption layer one and the excitation light absorption layer two are different, and the absorption coefficient of the excitation light absorption layer one for the laser wavelength emitted by the excitation light source is greater than the absorption coefficient of the excitation light absorption layer two for the laser wavelength emitted by the excitation light source.

[0009] In some embodiments, the multiple visible light wavelength generating components include a visible light wavelength one generating component and a visible light wavelength two generating component; the polarization phase matching nonlinear element one in the visible light wavelength one generating component is coated with a film layer with high transmittance to fundamental frequency wavelength one and visible light wavelength one on both light-transmitting end faces, so that the laser beam of polarized fundamental frequency wavelength one generates a laser beam of visible light wavelength one after passing through the polarization phase matching nonlinear element one; the visible light wavelength one output mirror in the visible light wavelength one generating component is coated with a film layer with high reflectivity to polarized fundamental frequency wavelength one and high transmittance to visible light wavelength one on the incident surface, and is coated with a film layer with high transmittance to visible light wavelength one on the output surface.

[0010] In some embodiments, the polarization phase matching nonlinear element 2 in the visible light wavelength 2 generating component is coated with a film layer with high transmittance to fundamental frequency wavelength 2 and visible light wavelength 2 on both light-transmitting end faces, so that the laser beam of polarized fundamental frequency wavelength 2 generates a laser beam of visible light wavelength 2 after passing through the polarization phase matching nonlinear element 2; the visible light wavelength 2 output mirror in the visible light wavelength 2 generating component is coated with a film layer with high reflectivity to polarized fundamental frequency wavelength 2 and high transmittance to visible light wavelength 2 on the incident surface, and is coated with a film layer with high transmittance to visible light wavelength 2 on the output surface.

[0011] In some embodiments, the material lattice constant of the substrate matches the material lattice constant of the integrated broadband reflector and the multi-wavelength fundamental frequency light emission region; the chip protection layer uses a weakly oxidizing material; and the excitation light wavelength transmittance-enhancing layer is a film layer with high transmittance to the laser wavelength emitted by the excitation light source.

[0012] In some embodiments, the pump part also includes: a converging lens 1 and a converging lens 2, wherein the converging lens 1 is located between the excitation light source and the converging lens 2; the converging lens 1 is coated on both sides with a film layer with a high transmittance to the laser wavelength emitted by the excitation light source, and the light beam emitted by the excitation light source becomes a parallel light beam after passing through the converging lens 1; the converging lens 2 is coated on both sides with a film layer with a high transmittance to the laser wavelength emitted by the excitation light source, and the parallel light beam emitted from the converging lens 1 is focused onto the integrated gain reflector after passing through the converging lens 2.

[0013] In some embodiments, the multi-wavelength visible light laser further includes: a heat dissipation device, which is welded to the substrate of the integrated gain reflector through at least one layer of metal thin plate with high thermal conductivity, and is used to dissipate heat from the integrated gain reflector, wherein the heat dissipation method of the heat dissipation device includes at least one of the following: a passive heat dissipation method through heat dissipation fins, or an active heat dissipation method through air cooling or water cooling.

[0014] The above-mentioned various embodiments of the present disclosure have the following beneficial effects: some embodiments of the present disclosure are based on a multi-wavelength visible light laser controlled by a single gain medium and polarization, and generate a multi-wavelength fundamental frequency laser beam by setting a broadband reflector and a multi-wavelength fundamental frequency light emission area in an integrated gain reflector. Then, the fundamental frequency lights of different wavelengths are separated by a polarization control device, and the frequency doubling and other controls are performed separately to obtain visible light laser outputs of different wavelengths. In this way, the limitations of existing visible light lasers, such as a single wavelength, a complex optical structure, poor stability and reliability, and non-tunable wavelength, can be solved. Thereby, the application range of the laser can be significantly expanded to meet the use requirements of more application scenarios.

[0015] Specifically, a small number of lasers in the visible light band can be obtained from liquid or gas gain media, such as dye lasers. However, the efficiency of this method is extremely low, and dyes are generally toxic and difficult to store and maintain. Gas lasers such as argon ions and helium-neon can also emit several lasers in the visible light band. However, these methods require high-voltage discharge excitation, have poor stability, and have extremely limited output power. In addition, lasers in the visible light bands such as blue, green, and red can also be obtained from semiconductor laser diodes. The obvious disadvantage of this method is that the band is still relatively single and the beam quality is very poor, so that it cannot be directly applied in many practical scenarios. In addition, a small number of lasers in the visible light band can also be obtained from solid-state lasers through nonlinear frequency conversion such as frequency doubling or parametric oscillation. However, the disadvantages of this method are that the wavelength is relatively single, the efficiency is relatively low, and the structure is very complex, and the stability, reliability, and portability are not satisfactory.

[0016] Based on this, some embodiments of the present disclosure are based on a single gain medium and polarization controlled multi-wavelength visible light laser, using a single semiconductor gain medium, by setting a broadband reflector and a multi-wavelength fundamental frequency light emission area in an integrated gain reflector, it is possible to generate a multi-wavelength fundamental frequency laser beam. Then the fundamental frequency light of different wavelengths is separated by a polarization control device. After that, frequency doubling and other controls can be performed separately to obtain visible light laser outputs of different wavelengths. The laser disclosed in the present disclosure can generate visible light band laser outputs of different wavelengths in the same laser using a single gain medium. Its emission wavelength can be adjusted by changing the material composition of the relevant part in the gain medium, and the wavelength is not only continuously adjustable, but also has a wide range of wavelength coverage. Therefore, it can replace dye lasers and gas lasers to a certain extent, filling the wavelength blank area that solid lasers cannot reach. In addition, the optical structure of the laser disclosed in the present disclosure is simpler and more compact, and its stability and reliability are better than other types of existing visible light lasers, and it can emit at least two laser wavelengths at the same time, which greatly improves and expands its application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that components and elements are not necessarily drawn to scale.

[0018] Figure 1 It is a schematic diagram of the structural principle of some embodiments of the multi-wavelength visible light laser based on a single gain medium and separate polarization control disclosed in the present invention;

[0019] Figure 2 yes Figure 1 Structural diagrams of some embodiments of integrated gain reflectors;

[0020] Figure 3 yes Figure 1 The broadband reflection spectrum of the integrated broadband reflector in the integrated gain reflector;

[0021] Figure 4 yes Figure 1 The integrated gain reflector has a fundamental frequency wavelength one gain spectrum, a fundamental frequency wavelength two gain spectrum and a comprehensive gain spectrum. DETAILED DESCRIPTION

[0022] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0023] It should also be noted that, for ease of description, only the parts related to the invention are shown in the drawings. In the absence of conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0024] It should be noted that the concepts such as "first" and "second" mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0025] In addition, the modifications of "one" and "plurality" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, they should be understood as "one or more".

[0026] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0027] The reference numerals in the drawings of the specification include: excitation light source 1, converging lens 1 2, converging lens 2 3, integrated gain reflector 4, heat dissipation device 5, multi-wavelength laser beam 6, polarization control device 7, p-polarization fundamental frequency wavelength 1 laser beam 8, p-polarization phase matching nonlinear element 1 9, visible light wavelength 1 output mirror 10, visible light wavelength 1 laser beam 11, s-polarization fundamental frequency wavelength 2 laser beam 12, s-polarization phase matching nonlinear element 2 13, visible light wavelength 2 output mirror 14, visible light wavelength 2 laser beam 15, substrate 16 , integrated broadband reflector 17, multi-wavelength fundamental frequency light emission area 18, carrier confinement layer 19, chip protection layer 20, excitation light wavelength transmittance enhancement layer 21, high refractive index layer 22, low refractive index layer 23, fundamental frequency wavelength one emission layer 24, excitation light absorption layer one 25, fundamental frequency wavelength two emission layer 26, excitation light absorption layer two 27, different wavelength carrier locking layer 28, fundamental frequency wavelength one high reflection spectrum 29, fundamental frequency wavelength two high reflection spectrum 30, fundamental frequency wavelength one gain spectrum 31, fundamental frequency wavelength two gain spectrum 32, comprehensive gain spectrum 33.

[0028] like Figure 1 As shown, the multi-wavelength visible light laser based on a single gain medium and polarization control according to the present disclosure may include a pump part, an integrated gain reflector 4, a polarization control device 7 and a plurality of visible light wavelength generating components. Here, the pump part is mainly used to emit a laser wavelength, which may include an excitation light source 1. The laser wavelength emitted by the excitation light source 1 can be Figure 2 The light is absorbed by the multi-wavelength fundamental frequency light emitting region 18 in the integrated gain reflector 4.

[0029] Here, the integrated gain reflector 4 is used to perform bandwidth reflection of different fundamental wavelengths on the laser wavelength emitted by the pump part, and emit multi-wavelength laser beams with different fundamental wavelengths. Figure 2 As shown, the integrated gain reflector 4 may include a substrate 16, an integrated broadband reflector 17, a multi-wavelength fundamental frequency light emitting region 18, a chip protection layer 20, and an excitation light wavelength anti-reflection layer 21. Figure 2 As can be seen in the figure, the integrated broadband reflector 17, the multi-wavelength fundamental frequency light emitting region 18, the chip protection layer 20, and the excitation light wavelength anti-reflection layer 21 are sequentially fixed on the same side of the substrate 16. Here, the integrated broadband reflector 17 can provide broadband reflection of different fundamental frequency wavelengths. The multi-wavelength fundamental frequency light emitting region 18 can emit multi-wavelength laser beams of different fundamental frequency wavelengths.

[0030] Furthermore, the polarization control device 7 is used to separate the multi-wavelength laser beam emitted by the integrated gain reflector 4 by polarization state, so as to obtain a plurality of laser beams with different polarization fundamental frequency wavelengths. Among them, the polarization control device 7 can be coated with a film layer with high transmittance to polarization fundamental frequency wavelength 1 and high reflectance to polarization fundamental frequency wavelength 2 on the incident surface; and can be coated with a film layer with high transmittance to polarization fundamental frequency wavelength 1 on the exit surface. In this way, when the multi-wavelength laser beam emitted by the integrated gain reflector 4 passes through the incident surface of the polarization control device 7, Figure 1 As shown, a portion of the laser beam wavelengths (such as the p-polarized fundamental frequency wavelength one laser beam 8) will pass through the polarization control device 7, while another portion of the laser beam wavelengths (such as the s-polarized fundamental frequency wavelength two laser beam 12) will be reflected by the polarization control device 7, thereby achieving the separation of laser beams of different wavelengths.

[0031] In addition, the multiple visible light wavelength generating components can be used to perform frequency conversion on the laser beams with different polarization fundamental wavelengths output by the polarization control device 7, respectively, so as to output laser beams with different visible light wavelengths. Here, the multiple visible light wavelength generating components may include polarization phase matching nonlinear elements (such as Figure 1 9, 13) and visible wavelength output mirrors (such as Figure 1 10, 14).

[0032] It can be seen from the above description that the multi-wavelength visible light laser based on a single gain medium and polarization control disclosed in the present invention, first, by setting an integrated broadband reflector and a multi-wavelength fundamental frequency light emission area in the gain medium (i.e., an integrated gain reflector). In this way, only a single gain medium is used to generate multi-wavelength visible light output, and the functions of multiple lasers in the past are realized in one laser. Secondly, by using polarization control, different fundamental frequency light wavelengths emitted from a single gain medium can be separated, and after frequency conversion, visible light laser outputs of different wavelengths can be generated. In this way, while greatly enriching the functions of the visible light laser, the resonant cavity structure can be greatly simplified. The entire laser structure is simple, compact and miniaturized, and the stability and reliability are significantly improved. Third, the multi-wavelength visible light laser disclosed in the present invention can also adjust the emission wavelength of the laser according to actual needs by changing the material composition of each relevant layer in the integrated gain reflector. In this way, the emission wavelength of the laser can be greatly enriched, the application range of the laser can be greatly expanded, and more and more prominent advantages can be obtained than the existing visible light laser.

[0033] It should be noted that from Figure 1 It can be seen that the pump part and the polarization control device 7 are both located on the same side of the integrated gain reflector 4. The structures of each part in the multi-wavelength visible light laser disclosed in the present invention can be set according to actual needs.

[0034] As an example, Figure 1 The pumping part shown may also include: a converging lens 1 2 and a converging lens 2 3. Among them, the converging lens 1 2 is located between the excitation light source 1 and the converging lens 2 3. Both sides of the converging lens 1 2 may be coated with a film layer with a high transmittance to the laser wavelength emitted by the excitation light source 1. After the light beam emitted by the excitation light source 1 passes through the converging lens 1 2, it can be converted into a parallel light beam. Both sides of the converging lens 2 3 may also be coated with a film layer with a high transmittance to the laser wavelength emitted by the excitation light source 1. After passing through the converging lens 2 3, the parallel light beam emitted by the converging lens 2 can be focused onto the integrated gain reflector 4.

[0035] In some embodiments, the substrate 16 in the integrated gain reflector 4 may be a material having a lattice constant that roughly matches that of the material in the integrated broadband reflector 17 and the multi-wavelength fundamental frequency light emitting region 18, and does not need to be doped. The integrated broadband reflector 17 may be composed of at least two refractive layers with different refractive indices alternating to provide broadband reflectivity of different fundamental frequency wavelengths. For example Figure 2 As shown, the integrated broadband reflector 17 can be composed of alternating high refractive index layers 22 and low refractive index layers 23, and can provide broadband reflectivity including fundamental frequency wavelength 1 and fundamental frequency wavelength 2. Figure 3 FIG. 2 shows a fundamental frequency wavelength one high reflection spectrum 29 and a fundamental frequency wavelength two high reflection spectrum 30 obtained by the integrated broadband reflector 17 .

[0036] In this case, the multi-wavelength fundamental frequency light emission region 18 may include a fundamental frequency wavelength emission layer, an excitation light absorption layer 1 25, and an excitation light absorption layer 2 27. The fundamental frequency wavelength emission layer may be alternately arranged with the excitation light absorption layer 1 25 to form a first emission region. In addition, the fundamental frequency wavelength emission layer may also be alternately arranged with the excitation light absorption layer 2 27 to form a second emission region. Here, the excitation light absorption layer 1 25 and the excitation light absorption layer 2 27 have different components, so that the absorption of the laser wavelength emitted by the excitation light source 1 is different.

[0037] Optionally, the multi-wavelength fundamental frequency light emission zone 18 may include a fundamental frequency wavelength one emission layer 24, an excitation light absorption layer one 25, a fundamental frequency wavelength two emission layer 26, and an excitation light absorption layer two 27. Among them, the fundamental frequency wavelength one emission layer 24 and the excitation light absorption layer one 25 can be alternately arranged to form a first emission zone. The fundamental frequency wavelength two emission layer 26 and the excitation light absorption layer two 27 can be alternately arranged to form a second emission zone. In addition, the chip protection layer 20 can be a material that is not easily oxidized. This can protect the integrated gain reflector 4 from being oxidized when it is in the air. The excitation light wavelength transmittance-enhancing layer 21 can be a film layer with high transmittance to the laser wavelength emitted by the excitation light source 1. This allows almost all of the laser wavelength to enter the integrated gain reflector 4.

[0038] It is understandable that the locations of the first emission area and the second emission area are not limited. The excitation light absorption layer 1 25 and the excitation light absorption layer 2 27 in the multi-wavelength fundamental frequency light emission area 18 can absorb the laser wavelength emitted by the excitation light source 1. As an example, Figure 2 As shown, the first emission region may be located between the integrated broadband reflector 17 and the second emission region.

[0039] In this case, the components of the first excitation light absorption layer 25 and the second excitation light absorption layer 27 are often different, and the absorption coefficient of the first excitation light absorption layer 25 to the laser wavelength emitted by the excitation light source 1 can be greater than the absorption coefficient of the second excitation light absorption layer 27 to the laser wavelength emitted by the excitation light source 1. Therefore, even if the first excitation light absorption layer 25 is located after the second excitation light absorption layer 27, the absorption of the laser wavelength emitted by the excitation light source 1 by both layers is roughly the same.

[0040] It should be noted that in the process of using the multi-wavelength visible light laser disclosed in the present invention, the following technical problems will also exist: the excitation light absorption layer will generate photogenerated carriers after absorbing the laser wavelength. These photogenerated carriers will diffuse to the surrounding fundamental wavelength emission layer to generate stimulated radiation, thereby generating a laser beam corresponding to the fundamental wavelength. Since the activity of the carriers is uncontrollable, and the first emission zone is adjacent to the second emission zone. In this way, the carriers located at the junction of the first emission zone and the second emission zone may interfere with each other. That is, the carriers generated by the excitation light absorption layer 1 25 may run into the fundamental wavelength 2 emission layer 26 of the second emission zone. And the carriers generated by the excitation light absorption layer 2 27 may run into the fundamental wavelength 1 emission layer 24 of the first emission zone. In addition, the carriers generated by the fundamental wavelength 1 emission layer 24 may also run to the first emission zone. The carriers generated by the fundamental wavelength 2 emission layer 26 may also run to the second emission zone. This will not only affect the intensity of the laser beam to be generated in different emission areas, but also affect the fundamental wavelength of the laser beam, and thus affect the visible light laser beam finally generated.

[0041] To solve this technical problem, the following technical solution can be adopted. In some embodiments, in order to avoid mutual interference between different emission areas in the multi-wavelength fundamental frequency light emission area 18, the multi-wavelength fundamental frequency light emission area 18 can also include a different wavelength carrier locking layer 28. The different wavelength carrier locking layer 28 can be between the first emission area and the second emission area. Among them, the material barrier height of the different wavelength carrier locking layer 28 is greater than the height of the material barrier of the fundamental frequency wavelength one emission layer 24 and the fundamental frequency wavelength two emission layer 26, and is less than the energy of the laser wavelength emitted by the excitation light source 1. In this way, under the action of the different wavelength carrier locking layer, the normal injection of the laser wavelength can be guaranteed, and the mutual diffusion and influence of the carriers in the excitation light absorption layer 1 25 and the excitation light absorption layer 2 27, as well as the carriers in the fundamental frequency wavelength one emission layer 24 and the fundamental frequency wavelength two emission layer 26 can be reduced or avoided.

[0042] Under the action of the different wavelength carrier locking layer 28, the photogenerated carriers generated by the excitation light absorption layer 1 25 after absorbing the laser wavelength emitted by the excitation light source 1 can be diffused into the fundamental wavelength one emission layer 24. In this way, the photogenerated carriers diffused from the excitation light absorption layer 1 25 can generate stimulated radiation in the fundamental wavelength one emission layer 24. Thus, the fundamental wavelength one emission layer 24 emits a laser beam of fundamental wavelength one. At the same time, the photogenerated carriers generated by the excitation light absorption layer 2 27 after absorbing the laser wavelength emitted by the excitation light source 1 can be diffused into the fundamental wavelength two emission layer 26. The photogenerated carriers diffused from the excitation light absorption layer 2 27 can generate stimulated radiation in the fundamental wavelength two emission layer 26. Thus, the fundamental wavelength two emission layer 26 emits a laser beam of fundamental wavelength two. Here, the components of the fundamental wavelength one emission layer 24 and the fundamental wavelength two emission layer 26 in the multi-wavelength fundamental frequency light emission region 18 are also different. That is to say, by providing the carrier locking layer 28 with different wavelengths, the two emission regions can be blocked, so that the carriers of the first emission region can only move in the first emission region, and the carriers of the second emission region can only move in the second emission region. This not only ensures that different emission regions can generate laser beams with corresponding fundamental wavelengths, but also helps to ensure the intensity of the laser beam, thereby generating visible light lasers with the required intensity and wavelength.

[0043] It can be understood that, in the above-mentioned multi-wavelength fundamental frequency light emitting area 18, the number of different emitting areas can also be set according to actual needs, such as according to the number of different wavelengths of visible light to be output by the laser.

[0044] Furthermore, the number of visible light wavelength generating components can also be set according to actual needs. Figure 1For example, the multiple visible light wavelength generating components disclosed in the present invention may include a visible light wavelength one generating component and a visible light wavelength two generating component. Here, the polarization phase matching nonlinear element one 9 in the visible light wavelength one generating component may be coated with a film layer with high transmittance to the fundamental frequency wavelength one and the visible light wavelength one on both light-transmitting end faces. In this way, after the polarization fundamental frequency wavelength one laser beam 8 passes through the polarization phase matching nonlinear element one 9, a laser beam with visible light wavelength one can be generated. At the same time, the visible light wavelength one output mirror 10 in the visible light wavelength one generating component may be coated with a film layer with high reflectivity to the polarization fundamental frequency wavelength one and high transmittance to the visible light wavelength one on the incident surface, and may be coated with a film layer with high transmittance to the visible light wavelength one on the exit surface. After passing through the visible light wavelength one output mirror 10, a visible light wavelength one laser beam 11 can be generated.

[0045] Similarly, the polarization phase matching nonlinear element 2 13 in the visible light wavelength 2 generating component can be coated with a film layer with high transmittance to the fundamental frequency wavelength 2 and the visible light wavelength 2 on both light-transmitting end faces. In this way, the laser beam 12 of the polarized fundamental frequency wavelength 2 can generate a laser beam of the visible light wavelength 2 after passing through the polarization phase matching nonlinear element 2 13. At the same time, the visible light wavelength 2 output mirror 14 in the visible light wavelength 2 generating component is coated with a film layer with high reflectance to the polarization fundamental frequency wavelength 2 and high transmittance to the visible light wavelength 2 on the incident surface, and is coated with a film layer with high transmittance to the visible light wavelength 2 on the exit surface. After passing through the visible light wavelength 2 output mirror 14, a visible light wavelength 2 laser beam 15 can be generated.

[0046] Here, the polarization phase matching nonlinear element 1 9 and the polarization phase matching nonlinear element 2 13 can adopt the critical phase matching or noncritical phase matching method. Among them, critical phase matching (also called angle phase matching) is a phase matching of a nonlinear process in a birefringent crystal. The interacting light beams are incident along a certain angle of the refractive index ellipsoid. In most cases, the polarization direction of one or two light beams is along a certain axis of the refractive index ellipsoid (ordinary light), while the polarization direction of the other one or two light beams is on the plane formed by the other two axes. By adjusting the propagation direction of the light beam, the refractive index of the extraordinary light can be adjusted, while the refractive index of the ordinary light remains unchanged. Phase matching can be achieved at certain special angles. Noncritical phase matching (sometimes also called temperature phase matching or 90° phase matching) is a phase matching technology used to obtain nonlinear processes. The two interacting light beams propagate along a certain axis of the birefringent nonlinear crystal. The phase mismatch is reduced by adjusting the crystal temperature to make the phase velocities of the two interacting light beams equal.

[0047] In some embodiments, the multi-wavelength visible light laser of the present disclosure may further include a heat dissipation device. Figure 1As shown, the heat sink 5 can be welded to the substrate of the integrated gain reflector 4 through at least one layer of metal thin plate with high thermal conductivity, so as to dissipate heat from the integrated gain reflector. The heat dissipation method of the heat sink includes at least one of the following: passive heat dissipation through heat dissipation fins, or active heat dissipation through air cooling or water cooling.

[0048] The working principle of this technical solution is that the excitation light beam emitted from the excitation light source is converged into a parallel light beam after passing through the converging lens 1, and then converged by the converging lens 2, and is focused on the integrated gain reflector at a certain angle. Because the surface of the integrated gain reflector is coated with an excitation light wavelength transmittance enhancement layer, almost all of the light beam emitted by the excitation light source enters the integrated gain reflector and is absorbed by the excitation light absorption layer 1 and the excitation light absorption layer 2 in the multi-wavelength fundamental frequency light emission area.

[0049] After absorbing the energy of the excitation light, the first and second excitation light absorption layers generate photogenerated carriers, which are diffused into the first and second emission layers of the fundamental wavelength in the multi-wavelength fundamental frequency light emission region, respectively, to generate stimulated radiation transitions, and emit the fundamental wavelengths 1 and 2. Since different wavelength carrier locking layers are provided in the integrated gain reflector, the carriers in the first and second excitation light absorption layers, and the first and second emission layers of the fundamental wavelength will not affect each other.

[0050] The integrated broadband reflector in the integrated gain reflector has high reflectivity for both fundamental wavelength 1 and fundamental wavelength 2, and forms a resonant cavity with the visible wavelength 1 output mirror. At the same time, the integrated broadband reflector and the visible wavelength 2 output mirror in the integrated gain reflector also form a resonant cavity. After passing through the polarization control device, the multi-wavelength laser beam composed of fundamental wavelength 1 and fundamental wavelength 2 emitted from the integrated gain reflector is separated into a p-polarized fundamental wavelength 1 laser beam and an s-polarized fundamental wavelength 2 laser beam having different wavelengths and polarization states, because the polarization control device is coated with film layers with different reflectivity and transmittance for different polarization states of different wavelengths on the incident surface and the exit surface.

[0051] The p-polarized fundamental wavelength laser beam forms laser oscillation in the laser resonant cavity composed of the integrated broadband reflector and the visible light wavelength output mirror in the integrated gain reflector. After the laser oscillation passes through the p-polarized phase matching nonlinear element, the frequency is converted to generate a visible light wavelength laser beam, which is output through the visible light wavelength output mirror coated with a certain transmittance film layer on the visible light wavelength.

[0052] The s-polarized fundamental frequency wavelength 2 laser beam forms laser oscillation in a laser resonant cavity composed of an integrated broadband reflector and a visible light wavelength 2 output mirror in an integrated gain reflector. After passing through the s-polarized phase matching nonlinear element 2, the laser oscillation undergoes frequency conversion to generate a visible light wavelength 2 laser beam, and is output through a visible light wavelength 2 output mirror coated with a certain transmittance film layer on the visible light wavelength 2.

[0053] At this point, a single gain medium is used to emit different fundamental frequency laser wavelengths. Then, the fundamental frequency lasers of different wavelengths are polarized and converted by different nonlinear elements. In one laser, multi-wavelength visible light laser output is obtained.

[0054] It should be noted that in the process of using the multi-wavelength visible light laser disclosed in the present invention, the following technical problems may further exist: since a plurality of excitation light absorption layers and a plurality of fundamental wavelength emission layers are provided in the multi-wavelength fundamental frequency light emission region in the integrated gain reflector 4, a plurality of carriers may be diffused in the integrated gain reflector 4. These carriers are likely to produce non-radiative recombination, thereby affecting the performance of the multi-wavelength visible light laser.

[0055] To solve this technical problem, the following technical solution can be adopted. The integrated gain reflector 4 can also include a carrier confinement layer. Figure 2 As shown, the carrier confinement layer 19 can be located between the multi-wavelength fundamental frequency light emission region 18 and the chip protection layer 20. Here, the material barrier of the carrier confinement layer 19 can be greater than the material barrier of each layer in the multi-wavelength fundamental frequency light emission region, and greater than the energy of the laser wavelength emitted by the laser light source, so as to prevent the photogenerated carriers from diffusing to the surface of the integrated gain reflector and generating non-radiative recombination. That is, the material barrier of the carrier confinement layer 19 is greater than the material barrier of the fundamental frequency wavelength one emission layer 24, the excitation light absorption layer one 25, the fundamental frequency wavelength two emission layer 26, the excitation light absorption layer two 27, and the different wavelength carrier locking layer 28, and is also greater than the energy of the photons emitted by the laser light source 1.

[0056] Since the carrier confinement layer at the front end of the integrated gain reflector is transparent to the excitation light wavelength. Therefore, the light beam emitted by the excitation light source can almost completely enter the integrated gain reflector, and at the same time, it can prevent the carriers from diffusing to the surface of the integrated gain reflector 4 to produce non-radiative recombination. This can reduce or avoid the impact of non-radiative recombination on the carrier lifetime and laser beam intensity. In addition, non-radiative recombination may also cause the laser to generate additional heat during operation. If this heat is not dissipated in time, it may affect the stability and life of the laser. Therefore, by setting a carrier confinement layer, it can be beneficial to improve the performance and reliability of the laser.

[0057] Specifically, in the multi-wavelength visible light laser based on a single gain medium and polarization control respectively disclosed in the present invention, the excitation light source 1 is a fiber-coupled output semiconductor laser module with an emission wavelength of 808 nm, and the diameter of the pigtail is 400 μm. The converging lens 1 2 and the converging lens 2 3 are both achromatic lenses with a diameter of 12.7 mm and a focal length of 30 mm, and the two form an optical imaging lens pair with 1:1 imaging, focusing the light beam emitted by the excitation light source on the integrated gain reflector 4.

[0058] The structure of the integrated gain reflector 4 is as follows: Figure 2 As shown. The substrate 16 is made of GaAs material with a thickness of 350 μm. The high refractive index layer 22 in the integrated broadband reflector 17 is GaAs with a thickness of 71 nm; the low refractive index layer 23 is AlAs with a thickness of 83 nm. The broadband reflection spectrum of the integrated broadband reflector 17 is shown in Figure 3 As shown, the central wavelength is at 1000nm, and the broadband reflection spectrum includes wavelengths of 980nm and 1020nm.

[0059] The fundamental frequency wavelength one emission layer 24 in the multi-wavelength fundamental frequency light emission zone 18 in the integrated gain reflector 4 is made of InGaAs material, with a thickness of 8nm and a fluorescence peak wavelength of 980nm; the excitation light absorption layer one 25 is made of GaAs material; the fundamental frequency wavelength two emission layer 26 is made of InGaAs material, with a thickness of 8nm and a fluorescence peak wavelength of 1020nm; and the excitation light absorption layer two 27 is made of GaAs material. Among them, the fundamental frequency wavelength one emission layer 24 and the fundamental frequency wavelength two emission layer 26 have different In content ratios in their materials. The different wavelength carrier locking layer 28 is made of AlGaAs material, which can prevent the carrier generation between the fundamental frequency wavelength one emission layer 24 and the excitation light absorption layer one 25 and the fundamental frequency wavelength two emission layer 26 and the excitation light absorption layer two 27 from influencing each other. The gain spectrum generated by the above-mentioned multi-wavelength fundamental frequency light emission zone 18 is as follows: Figure 4 As shown, the peak is relatively flat, including the 980nm wavelength and the 1020nm wavelength.

[0060] The carrier limiting layer 19 in the integrated gain reflector 4 is made of AlGaAs material, which can prevent the carriers in the fundamental wavelength 1 emission layer 24, the excitation light absorption layer 1 25, the fundamental wavelength 2 emission layer 26, and the excitation light absorption layer 2 27 from diffusing to the surface of the integrated gain reflector to generate non-radiative recombination. Among them, the content ratio of Al in the carrier limiting layer 19 is greater than the content ratio of Al in the different wavelength carrier locking layer 28.

[0061] The chip protection layer 20 in the integrated gain reflector 4 is made of GaAs material, which can protect the epitaxial layer in the integrated gain reflector 4 from oxidation. The excitation light wavelength anti-reflection layer 21 in the integrated gain reflector 4 is made of SiN material with a thickness of 70nm, which can increase the transmittance of the laser light source wavelength.

[0062] The heat sink 5 is a 4mm×4mm×0.5mm diamond sheet, which is a high thermal conductivity material. It can be welded to the integrated gain reflector 4 through multiple metal transition layers (such as gold, platinum, titanium), so as to dissipate heat for the integrated gain reflector 4. The solder here can be indium solder.

[0063] The multi-wavelength laser beam 6 includes a 980nm laser and a 1020nm laser. The polarization control device 7 is coated with a film layer with a high transmittance to the 980nm p-polarized fundamental wavelength wavelength 1 and a high reflectance to the 1020nm s-polarized fundamental wavelength wavelength 2 on the incident surface; and is coated with a film layer with a high transmittance to the 980nm p-polarized fundamental wavelength wavelength 1 on the exit surface. After passing through the polarization control device 7, the multi-wavelength laser beam 6 is spatially separated into a p-polarized fundamental wavelength wavelength 1 laser beam 8 with a wavelength of 980nm and an s-polarized fundamental wavelength 2 laser beam 12 with a wavelength of 1020nm.

[0064] The p-polarization phase matching nonlinear element 9 is a type I phase matching LBO (lithium triborate) crystal that phase matches the p-polarized light of 980nm wavelength, with a size of 3mm×3mm×10mm, and both light-transmitting surfaces are coated with a film layer that increases the transmittance of the p-polarized light of 980nm wavelength and the s-polarized light of 490nm wavelength. After the p-polarized light of 980nm wavelength passes through the p-polarization phase matching nonlinear element 9, the s-polarized visible light of 490nm wavelength is generated. The incident surface of the visible light wavelength output mirror 10 is coated with a high reflective mirror film layer for the p-polarized 980nm wavelength, and a film layer with high transmittance for the s-polarized 490nm wavelength; the exit surface of the visible light wavelength output mirror 10 is coated with a film layer with high transmittance for the s-polarized 490nm wavelength. The visible light wavelength laser beam 11 is the s-polarized visible light of 490nm wavelength.

[0065] The s-polarized fundamental frequency wavelength two laser beam 12 is s-polarized light with a wavelength of 1020nm. The s-polarized phase matching nonlinear element 13 is a type I phase matching LBO crystal that matches the phase of the s-polarized light of 1020nm. The size is 3mm×3mm×10mm. Both light-transmitting surfaces are coated with a film layer that increases the transmittance of the s-polarized light of 1020nm and the p-polarized light of 510nm. After the s-polarized light of 1020nm passes through the s-polarized phase matching nonlinear element 13, p-polarized 510nm visible light is generated. The incident surface of the visible light wavelength two output mirror 14 is coated with a high reflective mirror film layer for the s-polarized 1020nm wavelength, and a film layer with high transmittance for the p-polarized 510nm wavelength; the exit surface of the visible light wavelength two output mirror 14 is coated with a film layer with high transmittance for the p-polarized 510nm wavelength. The visible light wavelength two laser beam 15 is p-polarized 510nm visible light.

[0066] It should be noted that, in the above description, GaAs represents the material gallium arsenide; AlAs represents the material aluminum arsenide; In represents the material indium; Al represents the material aluminum; and SiN represents the material silicon nitride.

[0067] The above descriptions are only some preferred embodiments of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the embodiments of the present disclosure.

Claims

1. A multi-wavelength visible light laser based on a single gain medium and polarization control, comprising: A pump part, including an excitation light source, for emitting a laser wavelength; An integrated gain reflector, used for performing broadband reflection of different fundamental wavelengths on the laser wavelength emitted by the pump part and emitting multi-wavelength laser beams with different fundamental wavelengths, comprising a substrate and an integrated broadband reflector, a multi-wavelength fundamental wavelength light emitting region, a chip protection layer, and an excitation light wavelength anti-reflection layer sequentially fixed on the substrate; A polarization control device, used for separating the multi-wavelength laser beam emitted by the integrated gain reflector by polarization state to obtain a plurality of laser beams with different polarization fundamental frequency wavelengths, wherein the polarization control device is coated with a film layer with high transmittance to polarization fundamental frequency wavelength 1 and high reflectance to polarization fundamental frequency wavelength 2 on the incident surface, and is coated with a film layer with high transmittance to polarization fundamental frequency wavelength 1 on the exit surface; A plurality of visible light wavelength generating components, used for respectively performing frequency conversion on laser beams of different polarization fundamental frequency wavelengths output by the polarization control device, and outputting laser beams of different visible light wavelengths, including polarization phase matching nonlinear elements and visible light wavelength output mirrors; Wherein, the integrated broadband reflector is composed of two refractive layers with different refractive indices alternately, so as to provide broadband reflectivity including fundamental frequency wavelength 1 and fundamental frequency wavelength 2; The multi-wavelength fundamental frequency light emission zone includes: a fundamental frequency wavelength one emission layer, an excitation light absorption layer one, a fundamental frequency wavelength two emission layer, and an excitation light absorption layer two, wherein the fundamental frequency wavelength one emission layer and the excitation light absorption layer one are alternately arranged to form a first emission zone, and the fundamental frequency wavelength two emission layer and the excitation light absorption layer two are alternately arranged to form a second emission zone.

2. The multi-wavelength visible light laser based on a single gain medium and polarization control according to claim 1, wherein: The first emitting region is located between the integrated broadband reflector and the second emitting region; The components of the excitation light absorption layer 1 and the excitation light absorption layer 2 are different, and the absorption coefficient of the excitation light absorption layer 1 to the laser wavelength emitted by the excitation light source is greater than the absorption coefficient of the excitation light absorption layer 2 to the laser wavelength emitted by the excitation light source.

3. The multi-wavelength visible light laser based on a single gain medium and polarization control according to claim 1, wherein: The plurality of visible light wavelength generating components include a visible light wavelength one generating component and a visible light wavelength two generating component; The polarization phase matching nonlinear element 1 in the visible light wavelength 1 generating component is coated with a film layer with high transmittance to the fundamental frequency wavelength 1 and the visible light wavelength 1 on both light-transmitting end faces, so that the laser beam of the polarization fundamental frequency wavelength 1 generates a laser beam of the visible light wavelength 1 after passing through the polarization phase matching nonlinear element 1; The visible light wavelength output mirror in the visible light wavelength generating component is coated with a film layer with high reflectivity to the polarization fundamental frequency wavelength and high transmittance to the visible light wavelength on the incident surface, and is coated with a film layer with high transmittance to the visible light wavelength on the output surface.

4. The multi-wavelength visible light laser based on a single gain medium and polarization control according to claim 3, wherein: The second polarization phase matching nonlinear element in the second visible light wavelength generating component is coated with a film layer with high transmittance to the second fundamental frequency wavelength and the second visible light wavelength on both light-transmitting end faces, so that the laser beam of the second polarization fundamental frequency wavelength generates a laser beam of the second visible light wavelength after passing through the second polarization phase matching nonlinear element; The visible light wavelength 2 output mirror in the visible light wavelength 2 generating component is coated with a film layer with high reflectivity to the polarization fundamental frequency wavelength 2 and high transmittance to the visible light wavelength 2 on the incident surface, and is coated with a film layer with high transmittance to the visible light wavelength 2 on the exit surface.

5. The multi-wavelength visible light laser based on a single gain medium and polarization control according to claim 1, wherein: The material lattice constant of the substrate matches the material lattice constant of the integrated broadband reflector and the multi-wavelength fundamental frequency light emitting region; The chip protection layer is made of a material with weak oxidizability; The excitation light wavelength transmittance-enhancing layer is a film layer with high transmittance to the laser wavelength emitted by the excitation light source.

6. The multi-wavelength visible light laser based on a single gain medium and polarization control according to claim 1, wherein: The pump part further includes: a converging lens 1 and a converging lens 2, wherein the converging lens 1 is located between the excitation light source and the converging lens 2; The two sides of the converging lens 1 are coated with a film layer with a high transmittance to the laser wavelength emitted by the excitation light source, and the light beam emitted by the excitation light source becomes a parallel light beam after passing through the converging lens 1; The two sides of the converging lens 2 are coated with films with high transmittance to the laser wavelength emitted by the excitation light source. The parallel light beam emitted from the converging lens 1 passes through the converging lens 2 and is focused onto the integrated gain reflector.

7. The multi-wavelength visible light laser based on a single gain medium and polarization control according to any one of claims 1 to 6, wherein: The multi-wavelength visible light laser also includes: A heat dissipation device is welded to the substrate of the integrated gain reflector through at least one layer of metal thin plate with high thermal conductivity, and is used to dissipate heat from the integrated gain reflector, wherein the heat dissipation method of the heat dissipation device includes at least one of the following: a passive heat dissipation method through heat dissipation fins, or an active heat dissipation method through air cooling or water cooling.

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