A laser and method of generating laser light and a charging system

Abstract

The application provides a laser, a method for generating laser and a charging system. The laser provided by the application comprises a pumping source, a first cat-eye structure, a gain medium and a second cat-eye structure. The cat-eye constant L7 of the second cat-eye structure and the cat-eye constant of the first cat-eye structure satisfy a fixed relationship, that is, wherein A, B, C, D, E and f are intermediate quantities. Through the design method of the application, the distances between various components of the laser exist a specific relationship, the output power is stable, and a large range of debugging-free effect can be realized.

Description

Technical Field

[0001] This application relates to the technical fields of optical transmission networks, optical access and lidar, and in particular to a laser, a method for generating laser and a charging system. Background Technology

[0002] Distributed resonator lasers have important potential applications in sensing, communication, and energy transmission. For example, in the field of wireless laser energy transmission, photovoltaic cells and laser output mirrors can be integrated at the output end. In this case, the laser output from the output mirror will be automatically projected onto the photovoltaic cell, converting light energy into electrical energy. This can avoid the tracking system required in traditional laser energy transmission technology, and the laser will stop oscillating when there is an object cutting the light in the optical path, which has inherent safety.

[0003] When implementing wireless laser energy transmission to mobile devices, the relative direction and position of the laser receiver and laser transmitter are uncertain and may even move relative to each other. This requires the laser to be able to work without adjustment within a large working distance and field of view.

[0004] Current distributed resonant lasers, such as Figure 1 In the structure shown, to achieve adjustment-free operation, the reflector is typically placed at the focal plane of the lens, forming a "cat's eye" optical structure. For example, lenses 1-6 and reflectors 1-7 can form a cat's eye structure. This optical structure has a "retroreflection" characteristic, meaning that light rays incident at any angle through its pupil are reflected and propagated in the opposite direction along the incident light path. Laser resonators constructed using such devices can achieve adjustment-free laser operation. However, in practice, current distributed laser resonators based on cat's eye retroreflection devices require the radius of curvature to be equal to the lens focal length. However, this limitation results in misalignment on the order of a few minutes, which is insufficient for practical applications.

[0005] Therefore, how to improve the adjustment-free operating range of distributed resonant cavity adjustment-free lasers is an urgent problem to be solved. Summary of the Invention

[0006] This application provides a laser, a method for generating laser, and a charging system. By providing the distance calculation relationship between various components in the system, as well as the tolerance range of spherical aberration and field curvature of the system, the design freedom for the spacing of each component is increased. The distributed resonant cavity laser designed based on the method of this application has stable output power and achieves the effect of large-range adjustment-free operation.

[0007] In a first aspect, a laser is provided, comprising: a pump source, a first cat's-eye structure, a gain medium, and a second cat's-eye structure, wherein the pump source is used to acquire pump light, the first cat's-eye structure is the last cat's-eye structure before the gain medium, the first cat's-eye structure includes a first lens and a first partial reflector, the first cat's-eye structure obtains a first optical signal based on the pump light, the gain medium obtains a second optical signal using the first optical signal, the gain medium is placed at the exit pupil position of the first cat's-eye structure, the second cat's-eye structure obtains a third optical signal based on the second optical signal, the second cat's-eye structure is the last cat's-eye structure of the laser, the second cat's-eye structure includes a second lens and a second partial reflector, and the cat's-eye constant of the second cat's-eye structure is specified. The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... Satisfaction:

[0008] In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflector and the first lens. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens for the second gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

[0009] Optionally, the laser further includes a pump collimating lens for collimating the pump light to obtain collimated pump light. Specifically, the first cat's-eye structure is used to obtain a first optical signal based on the collimated pump light.

[0010] Based on the distributed resonant cavity laser provided in this application, the cat's-eye constant of the first cat's-eye structure is allowed to be different from the focal length of the lens in the second cat's-eye structure, and the cat's-eye constant of the second cat's-eye structure is also allowed to be different from the focal length in the third cat's-eye structure. That is, the design of the distributed resonant cavity laser based on this application allows for asymmetric laser emitters, making the design of the laser's structural parameters more flexible. Furthermore, the distributed resonant cavity laser provided in this application can clearly define the relationship between the distances of each segment of the distributed resonant cavity laser, thereby compensating for the influence of the thermal lens response in the laser gain medium on the retroreflection effect of the cat's-eye structure. The distributed resonant cavity laser provided in this application can achieve a wider range of adjustment-free operation. Simultaneously, considering the existence of a certain divergence angle in the beam at the receiving end, the distance between the receiving lens and the reflector can be optimized, thereby optimizing the laser's working distance range.

[0011] In conjunction with the first aspect, in certain implementations of the first aspect, the absolute value of the spherical aberration at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to 2. ,in, satisfy: .

[0012] In conjunction with the first aspect, in certain implementations of the first aspect, the absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to... ,in, satisfy: .

[0013] Based on the above scheme, the distributed resonant cavity laser provided in this application can correct the spherical aberration and / or field curvature of the system, and can compensate for the influence of spherical aberration and field curvature on the retroreflection effect of the cat's eye optical structure, thereby achieving the purpose of optimizing the laser's efficiency, working distance and field of view.

[0014] Secondly, an inherent structure for a laser is provided, comprising a laser emitting end and a laser receiving end. The laser emitting end includes a first cat's-eye structure; the laser receiving end includes a second cat's-eye structure. The first cat's-eye structure processes a first optical signal to obtain a second optical signal, and is the last cat's-eye structure of the laser emitting end. The first cat's-eye structure includes a first lens and a first partial reflector. The second cat's-eye structure obtains a third optical signal based on the second optical signal, and is the last cat's-eye structure of the laser receiving end. The second cat's-eye structure includes a second lens and a second partial reflector. The cat's-eye constant of the second cat's-eye structure is specified. The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... satisfy:

[0015] In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflector and the first lens. Let be the focal length of the first lens. Let be the focal length of the second lens. The wavelength of the laser. The laser spot radius input to the first cat's eye structure at the location is the laser spot radius at the first part of the reflector.

[0016] Based on the above scheme, the inherent structure of the distributed resonant cavity laser provided in this application allows the cat's-eye constant of the first cat's-eye structure to be different from the focal length of the first lens, and also allows the cat's-eye constant of the second cat's-eye structure to be different from the focal length of the second lens. That is, the design of the distributed resonant cavity laser based on this application allows for asymmetric laser emitters, making the design of the laser's structural parameters more flexible. Furthermore, based on the inherent structure of the distributed resonant cavity laser provided in this application, the relationship between the distances of each segment of the distributed resonant cavity laser is clarified, thereby compensating for the influence of the thermal lens response in the laser gain medium on the retroreflection effect of the cat's-eye structure. This enables the laser to achieve wide-range, adjustment-free operation. Simultaneously, considering the existence of a certain divergence angle in the beam at the receiving end, the distance between the receiving lens and the reflecting mirror can be optimized, thereby optimizing the laser's working distance range.

[0017] In conjunction with the second aspect, in some implementations of the second aspect, the absolute value of the spherical aberration at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to 2. ,in, satisfy: .

[0018] In conjunction with the second aspect, in some implementations of the second aspect, the absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to... ,in, satisfy: .

[0019] Based on the above scheme, the distributed resonant cavity laser provided in this application can correct the spherical aberration and / or field curvature of the system, and can compensate for the influence of spherical aberration and field curvature on the retroreflection effect of the cat's eye optical structure, thereby achieving the purpose of optimizing the laser's efficiency, working distance and field of view.

[0020] Thirdly, a laser is provided, comprising: a pump source, a third cat's-eye structure, a gain medium, a fourth cat's-eye structure, a first cat's-eye structure, and a second cat's-eye structure. The pump source is used to acquire pump light. The third cat's-eye structure obtains a first optical signal based on the pump light. The third cat's-eye structure is the last cat's-eye structure before the gain medium. The third cat's-eye structure includes a third lens and a third dichroic mirror. The gain medium obtains a second optical signal using the first optical signal. The fourth cat's-eye structure processes the second optical signal to obtain a third optical signal. The fourth cat's-eye structure... The first cat's-eye structure after the gain medium is configured. The fourth cat's-eye structure includes a fourth lens and a first partial reflector. The first cat's-eye structure obtains a fourth optical signal based on the third optical signal. The first cat's-eye structure is located between the fourth cat's-eye structure and the second cat's-eye structure. The first cat's-eye structure includes a first lens and a first partial reflector. The second cat's-eye structure obtains a fifth optical signal based on the fourth optical signal. The second cat's-eye structure is the last cat's-eye structure of the laser. The second cat's-eye structure includes a second lens and a second partial reflector. The cat's-eye constant of the second cat's-eye structure is... The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... satisfy:

[0021] In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first lens and the first partial reflector. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

[0022] Optionally, the laser further includes a pump collimating lens for collimating the pump light to obtain collimated pump light. Specifically, the third cat's-eye structure is used to obtain a first optical signal based on the collimated pump light.

[0023] Optionally, the cat's eye constant It can also satisfy:

[0024] In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the fourth lens and the first part of the reflecting mirror. The absolute value is the distance between the first lens and the first partial reflector. The absolute value is the distance between the fourth lens and the gain medium. The focal length of the fourth lens is... Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the gain medium is denoted as .

[0025] Based on the distributed resonant cavity laser provided in this application, the cat's eye constant of the cat's eye structure is no longer strictly equal to the lens focal length, which increases the flexibility of laser design and enables large-scale adjustment-free operation. Considering that the beam at the receiving end has a certain divergence angle, the design consensus of the distributed resonant cavity laser provided in this application can optimize the distance between the receiving end lens and the reflector, thereby optimizing the working distance range of the laser.

[0026] In conjunction with the third aspect, in certain implementations of the third aspect, the cat-eye constant of the fourth cat-eye structure... satisfy:

[0027] In the formula, intermediate quantities satisfy: intermediate quantity satisfy: ,in, The absolute value is the distance from the third lens to the gain medium. The focal length of the third lens is... The absolute value of is the cat's eye constant. The deviation from the ideal value, where the ideal value is... .

[0028] Based on the distributed resonant cavity laser provided in this application, the focal lengths of the third and fourth lenses can be the same or different. This is due to the thermal lens within the laser gain medium. The purpose of this is to ensure that the sum of the distances between the lenses and mirrors in the third and fourth cat's-eye structures is not equal to the focal length of each lens, but can be compensated for according to the above relationship. By selecting one value according to the structural design requirements and then determining the other using the above relationship, the structural design of lasers is facilitated.

[0029] In conjunction with the third aspect, in certain implementations of the third aspect, the aforementioned The following relationship must be satisfied:

[0030] In the formula, intermediate quantities satisfy: intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: .

[0031] Based on the above scheme, the distributed resonant cavity laser provided in this application embodiment allows the cat's-eye structure inside the laser to not strictly adhere to the stringent condition that the reflector must be placed at the focal plane of the lens. Instead, it allows for the design of the cat's-eye structure in the asymmetrical emitting end, making the design of the laser's structural parameters more flexible. Furthermore, considering errors in practical applications, the distance design of the distributed resonant cavity laser provided in this application is more flexible and reliable.

[0032] In conjunction with the third aspect, in certain implementations of the third aspect, the absolute value of the spherical aberration at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to 2. ,in, satisfy: .

[0033] In conjunction with the third aspect, in certain implementations of the third aspect, the absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to... ,in, satisfy: .

[0034] Based on the above scheme, the distributed resonant cavity laser provided in this application can compensate for the influence of aberrations such as spherical aberration and field curvature on the retroreflection effect of the cat's eye retroreflection structure, optimize the efficiency, working distance and field of view of the laser, and make the output power of the distributed resonant cavity laser more stable.

[0035] Fourthly, a method for generating laser light is provided, the method comprising: acquiring pump light; obtaining a first optical signal based on the pump light using a first cat's-eye structure, wherein the first cat's-eye structure is the last cat's-eye structure before the gain medium of the laser, and the first cat's-eye structure includes a first lens and a first partial reflector; obtaining a second optical signal using the first optical signal; obtaining a third optical signal based on the second optical signal using a second cat's-eye structure, wherein the second cat's-eye structure is the last cat's-eye structure of the laser, and the second cat's-eye structure includes a second lens and a second partial reflector, and a cat's-eye constant of the second cat's-eye structure. The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... Satisfaction:

[0036] In the middle, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflector and the first lens. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

[0037] Based on the beneficial effects of the above-mentioned solution, please refer to the corresponding description in the first aspect. For the sake of brevity, this application will not repeat it here.

[0038] In conjunction with the fourth aspect, in certain implementations of the fourth aspect, the absolute value of the spherical aberration at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to 2. ,in, satisfy: .

[0039] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to... ,in, satisfy: .

[0040] Based on the beneficial effects of the above-mentioned solution, please refer to the corresponding description in the first aspect. For the sake of brevity, this application will not repeat it here.

[0041] Fifthly, a method for generating laser light is provided, the method comprising: acquiring pump light; obtaining a first optical signal based on the pump light using a third cat's-eye structure, the third cat's-eye structure being the last cat's-eye structure before a gain medium, the third cat's-eye structure including a third lens and a third dichroic mirror; obtaining a second optical signal using the first optical signal using a fourth cat's-eye structure; processing the second optical signal using a fourth cat's-eye structure to obtain a third optical signal, the fourth cat's-eye structure being the first cat's-eye structure after the gain medium, the fourth cat's-eye structure including a fourth lens and a first partial reflector; obtaining a fourth optical signal based on the third optical signal using a first cat's-eye structure, the first cat's-eye structure being located between the fourth cat's-eye structure and the second cat's-eye structure, the first cat's-eye structure including a first lens and a first partial reflector; obtaining a fifth optical signal based on the fourth optical signal using a second cat's-eye structure, the second cat's-eye structure being the last cat's-eye structure of the laser, the second cat's-eye structure including a second lens and a second partial reflector; and a cat's-eye constant of the second cat's-eye structure. The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... satisfy:

[0042] In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first lens and the first partial reflector. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

[0043] Optionally, the cat's eye constant It can also satisfy:

[0044] In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity intermediate quantity intermediate quantity intermediate quantity intermediate quantity intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the fourth lens and the first part of the reflecting mirror. The absolute value is the distance between the first lens and the first partial reflector. The absolute value is the distance between the fourth lens and the gain medium. The focal length of the fourth lens is... Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the gain medium is denoted as .

[0045] Based on the beneficial effects of the above-mentioned scheme, please refer to the corresponding description in the third aspect. For the sake of brevity, this application will not repeat it here.

[0046] In conjunction with the fifth aspect, in certain implementations of the fifth aspect, the cat-eye constant of the fourth cat-eye structure... satisfy:

[0047] In the formula, intermediate quantities satisfy: intermediate quantity satisfy: ,in, The absolute value is the distance from the third lens to the gain medium. The focal length of the third lens is... The absolute value of is the cat's eye constant. The deviation from the ideal value, where the ideal value is... .

[0048] Based on the beneficial effects of the above-mentioned scheme, please refer to the corresponding description in the third aspect. For the sake of brevity, this application will not repeat it here.

[0049] In conjunction with the fifth aspect, in some implementations of the fifth aspect, the aforementioned The following relationship must be satisfied:

[0050] In the formula, intermediate quantities satisfy: intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: .

[0051] Based on the beneficial effects of the above-mentioned scheme, please refer to the corresponding description in the third aspect. For the sake of brevity, this application will not repeat it here.

[0052] In conjunction with the fifth aspect, in certain implementations of the fifth aspect, the absolute value of the spherical aberration at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to 2. ,in, satisfy: .

[0053] In conjunction with the sixth aspect, in some implementations of the sixth aspect, the absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to... ,in, satisfy: .

[0054] Based on the beneficial effects of the above-mentioned scheme, please refer to the corresponding description in the third aspect. For the sake of brevity, this application will not repeat it here.

[0055] In a sixth aspect, a charging system is provided, the system comprising: a laser, the laser including the laser described in either the first or second aspect; a control circuit for controlling an electrical switch in the charging system; and a drive circuit for providing a pump source for the laser.

[0056] In conjunction with the sixth aspect, in some implementations of the sixth aspect, the system further includes: a photovoltaic cell for receiving laser light generated by a laser as described in either the first or second aspect, and converting the light energy of the laser light into electrical energy. Attached Figure Description

[0057] Figure 1 A schematic diagram of a distributed resonant cavity laser provided by the prior art is shown.

[0058] Figure 2 A schematic diagram of the structure of the distributed resonant cavity laser 200 provided in an embodiment of this application is shown.

[0059] Figure 3 A schematic diagram of the structure of the distributed resonant cavity laser 300 provided in an embodiment of this application is shown.

[0060] Figure 4 A schematic diagram of the structure of the distributed resonant cavity laser 400 provided in an embodiment of this application is shown.

[0061] Figure 5 A schematic diagram of the structure of the distributed resonant cavity laser 500 provided in an embodiment of this application is shown.

[0062] Figure 6 A schematic diagram of the structure of the distributed resonant cavity laser 600 provided in an embodiment of this application is shown.

[0063] Figure 7 A schematic diagram of the structure of the distributed resonant cavity laser 700 provided in an embodiment of this application is shown.

[0064] Figure 8 A schematic diagram of the structure of the distributed resonant cavity laser 800 provided in an embodiment of this application is shown.

[0065] Figure 9 A schematic diagram of the structure of a distributed resonant cavity laser 900 provided in an embodiment of this application is shown.

[0066] Figure 10 A schematic flowchart of a laser generation method 1000 provided in an embodiment of this application is shown.

[0067] Figure 11 A schematic flowchart of a laser generation method 1100 provided in an embodiment of this application is shown.

[0068] Figure 12 A schematic diagram of the surface profile of an aspherical plano-convex lens with f=24.6mm provided in an embodiment of this application is shown.

[0069] Figure 13 A schematic diagram of the surface profile of an aspherical plano-convex lens with f=48.3mm provided in an embodiment of this application is shown.

[0070] Figure 14A schematic diagram of the field curvature calculation results of the laser output mirror 2-2 with an ROC of 51.8 mm provided in the embodiment of this application is shown.

[0071] Figure 15 A schematic diagram of the field curvature calculation results of the laser output mirror 2-2 with an ROC of 77.26 mm provided in the embodiment of this application is shown.

[0072] Figure 16 A schematic diagram is shown showing the output power of the laser at different focal lengths using the second lens 2-1 provided in this embodiment of the application.

[0073] Figure 17 A schematic diagram showing the simulation results of the laser emitter provided in the embodiments of this application is illustrated.

[0074] Figure 18 A schematic diagram of a laser receiver provided in an embodiment of this application is shown.

[0075] Figure 19 This illustrates another intent of the laser receiver provided in the embodiments of this application. Detailed Implementation

[0076] Currently, a distributed resonant cavity adjustment-free laser based on a cat's-eye inverse structure is being realized, employing methods such as... Figure 1 The multi-cat-eye optical structure shown, this distributed resonant cavity adjustment-free laser mainly includes: a laser emitter 1 and a laser receiver 2. The laser emitter 1 includes a pump source 1-1, a pump collimating lens 1-2, a laser total reflection mirror 1-3, a first intracavity lens 1-4, a laser gain medium 1-5, a second intracavity lens 1-6, an intracavity partial reflector 1-7, and a third intracavity lens 1-8. The laser receiver 2 includes a fourth intracavity lens 2-1 and a laser output mirror 2-2. Figure 1 middle, , , , These represent the distances between the laser total reflection mirror 1-3 and the first intracavity lens 1-4, the first intracavity lens 1-4 and the laser gain medium 1-5, the laser gain medium 1-5 and the second intracavity lens 1-6, and the second intracavity lens 1-6 and the intracavity partial reflector 1-7, respectively. This represents the distance between the internal cavity reflector 1-7 and the third cavity lens 1-8. This represents the distance between the third intracavity lens 1-8 and the fourth intracavity lens 2-1, and can also be called the working distance of a distributed resonant cavity laser that does not require adjustment. This represents the distance between the fourth intracavity lens 2-1 at the receiving end and the laser output mirror 2-2.

[0077] For laser energy transfer applications, it is generally desirable for the laser to have a large operating distance range, meaning the stable region of the resonant cavity can cover the expected operating distance. However, for lasers, the various parameters of the laser's stable region are interdependent. When one parameter has a large stable region range, the stable region range of other parameters must be sacrificed to some extent. Therefore, this is not the optimal result for other parameters.

[0078] by Figure 1 Taking the reference optical path shown as an example, for a resonant cavity composed of multiple cat's-eyes, when the working distance... When the stable zone is relatively large, for example, when the target range is 0.5m to 5m, The stable region will be less than 1 mm. Furthermore, The stable range is also proportional to the square of the focal length of lens 2-1. If the focal length F4 of lens 2-1 is further reduced, The stable region will be smaller.

[0079] Considering that in the general design of cat's eye retroreflection structure, the design optimization of the retroreflection characteristics of the beam is based on the case of parallel light entering through the pupil, in order to make the retroreflected beam also a parallel light that can return along the original path, the distance between the focusing lens and the reflecting mirror in the cat's eye structure is usually set to be equal to the focal length of the focusing lens.

[0080] However, for a cat's-eye structure, when the incident angle of the incident beam is not zero (i.e., the incident angle is not zero), the field curvature of a conventional spherical lens causes the beam to defocus after passing through the lens. Therefore, the original focal point of the lens will shift. Consequently, the reflecting surface of the mirror placed at the focal plane of the lens will not receive the focal point of the beam, meaning the cat's-eye structure has become defocused. It should be understood that this amount of defocusing actually reflects... The deviation from the optimal state within its stable region.

[0081] To illustrate this offset more specifically, Table 1 below shows the offset between the beam focal point and the reflecting surface caused by incident rays at different incident angles when the angles of the retroreflected light and the incident light are the same.

[0082] Table 1

[0083] It should be noted that in Table 1 The value is based on Figure 1 The surface of the reflector 2-2 shown is the zero point, and the direction towards the lens 2-1 is the positive direction for calculation.

[0084] Therefore, as can be seen from Table 1, regardless of whether a plane mirror or a concave mirror with a radius of curvature equal to the focal length of the lens is used as the reflecting mirror, the deviation already exceeds the above at a very small angle. The stable range of the laser makes it unable to work properly, thus limiting the laser's field of view.

[0085] Furthermore, considering that the laser beam emitted by the laser has a Gaussian distribution along the transverse direction, known as a Gaussian beam, due to the inherent divergence angle of a Gaussian beam, when the laser's working distance is long, the beam between the transmitter and receiver needs to be collimated to a larger spot size to compress the divergence angle. This results in a correspondingly larger laser spot size at the lens. Consequently, the edge rays of the spherical lens experience a stronger converging effect relative to the central rays, meaning the spherical lens produces significant spherical aberration. This aberration prevents rays from different radial positions of a large-aperture beam from converging to the same focal point. For a spherical lens, spherical aberration is positively correlated with the beam aperture and negatively correlated with the lens focal length. Therefore, the larger the beam aperture and the smaller the lens focal length, the more significant the negative impact of spherical aberration on the working distance becomes. In short, regardless of where the cat's-eye structure's reflector is placed, some light will always defocus and cannot be ideally reflected according to the characteristics of a cat's eye, resulting in energy loss and limiting the laser's conversion efficiency at long working distances.

[0086] Furthermore, the influence of the pump light and the intracavity signal light creates a temperature gradient within the laser crystal, resulting in varying degrees of thermal expansion and contraction. The temperature is highest in the center and decreases at the periphery, creating a gradient in the refractive index and thus forming a lens-like effect known as the thermal lensing effect. This thermal lensing effect severely impacts laser operation, affecting output power and beam quality. Therefore, even in a typical cat's-eye retroreflective structure, where the distance between the focusing lens and the reflecting mirror is typically equal to the lens's focal length (to optimize parallelism of both incident and retroreflected light), even disregarding factors like the incident angle and spherical aberration, the thermal lensing effect of the intracavity laser crystal in a long-working-distance distributed resonant cavity laser based on a cat's-eye structure will cause the focal points of the beams to de-align after focusing. In other words, light rays on the reflecting mirror plane at the lens focal point will inevitably defocus. Consequently, the stable operating range of the laser under this structure... The defocus offset is very narrow, and this amount of defocusing offset can cause the laser to become less efficient or even fail to function properly.

[0087] In conclusion, the current design requirements for cat-eye retroreflective structures, which stipulate that the distance between the focusing lens and the reflecting mirror in the cat-eye structure must be equal to the focal length of the focusing lens, cannot meet the needs of practical applications.

[0088] Based on the above analysis, this application proposes a distributed resonant cavity laser that considers the cat's-eye structure at the emitter as a whole, thereby increasing the degree of freedom in the spacing of each component. Furthermore, by fully considering the correction of spherical aberration and field curvature of the system, and combining the thermal lensing effect of the gain crystal in the laser, the distributed resonant cavity laser provided in this application possesses a wide range of adjustment-free operating distances and stable output power.

[0089] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0090] The following description is provided to facilitate understanding of the embodiments of this application.

[0091] In the embodiments shown below, the terms "first," "second," "third," "fourth," and various numerical designations are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. For example, they may distinguish different states of optical signals after different steps.

[0092] In the embodiments described below, the cat-eye structure is also referred to as a cat-eye retroreflector structure or a cat-eye retroreflector, etc.

[0093] In this embodiment of the application, the direction of the distributed resonant laser from left to right along the optical axis is defined as the positive direction.

[0094] It should also be noted that, in the embodiments of this application, a partial reflector refers to an element that can reflect a portion of the signal light and transmit a portion of the light in a corresponding proportion, which can be achieved by coating a partial reflective film with a certain reflectivity on the mirror surface.

[0095] It should be understood that the working distance mentioned in the embodiments of this application can be understood as the working distance in the general sense for distributed lasers, that is, the distance along the optical axis between the transmitting end and the emitting end. Specifically, for different lasers, it can be the distance along the optical axis between the last element of the laser transmitting end and the first element of the receiving end.

[0096] Furthermore, the dichroic mirror mentioned in the embodiments of this application can also be called a bichromatic mirror, which can transmit light of a certain wavelength almost completely while reflecting light of other wavelengths almost completely. Specifically, in the embodiments of this application, the dichroic mirror has high transmittance for pump light and high reflectivity for signal light generated inside the laser cavity.

[0097] Figure 2 A schematic diagram of a distributed resonant cavity laser 200 provided in an embodiment of this application is shown. Figure 2 As shown, the distributed resonant cavity laser 200 may include a laser emitter 1 and a laser receiver 2.

[0098] The laser emitter 1 consists of a pump source 1-1, a first part of the reflector 1-7, a first lens 1-8, and a gain medium 1-9. The first part of the reflector 1-7 and the first lens 1-8 constitute a first cat's eye structure.

[0099] The functions of each component are as follows: Pump source 1-1 is used to obtain pump light. For example, pump source 1-1 can be an 808nm fiber-coupled output semiconductor laser. This laser can output 808nm laser light as pump light input to the emitter of distributed resonant cavity laser 200.

[0100] The first cat's-eye structure obtains the first optical signal based on the pump light. The cat's-eye constant of the first cat's-eye structure is... , The absolute value is the distance between the first part of the reflecting mirror 1-7 and the first lens 1-8, wherein the first part of the reflecting mirror can be the first dichroic mirror.

[0101] It should be understood that the working principle of the cat's eye structure can be simply understood as follows: when a beam of parallel light is incident on the retroreflector, it will be emitted in the same direction.

[0102] Gain media 1-9 are used to obtain the second optical signal from the first optical signal described above. These gain media 1-9 can be α-cut neodymium-doped yttrium vanadate (Nd:YVO4) crystals with a doping concentration of 0.5% and dimensions of 4×4×4 mm. 3 This allows the generation of lasers with a wavelength of 1064nm, or other types of laser gain crystals.

[0103] It should be understood that the working principle of this gain medium can be simply understood as follows: the first optical signal pumps the particles in the gain medium from the ground state to a higher energy level, realizes population inversion and amplifies the light inside the gain medium, and outputs the second optical signal at the same time.

[0104] The laser receiver 2 includes a second cat's eye structure, which includes a second lens 2-1 and a second part of a reflector 2-2.

[0105] The second cat's eye structure obtains the third light signal based on the second light signal, and the cat's eye constant of the second cat's eye structure is: , The absolute value is the distance between the second lens 2-1 and the second partial mirror 2-2.

[0106] It should be noted that, in Figure 2 The distributed resonant cavity laser 200 shown may also contain other cat's-eye structures; this application is not limited to these, for example, it could be... Figure 1 The laser structure shown is also within the scope of protection of this application, or may be further described in... Figure 1 The distributed resonant laser shown, which adds or removes the cat's-eye structure, is also within the scope of protection of this application. Therefore, it should be emphasized that the first cat's-eye structure is the last cat's-eye structure at the laser emitting end of the laser, that is, the first cat's-eye structure is the last cat's-eye structure before the gain medium in the laser, and the second cat's-eye structure is the last cat's-eye structure at the laser receiving end of the laser.

[0107] It should be understood that, in the embodiments of this application, the first cat's-eye structure is the last cat's-eye structure before the gain medium in the laser, meaning that along the laser emission direction, such as... Figure 2 As shown, viewed from right to left, the first cat's eye structure is in front of the gain medium, meaning that the pump light emitted from the pump source will first pass through the first cat's eye structure before reaching the gain medium.

[0108] Optionally, the laser emitting end of the laser 200 may further include pump collimating lenses 1-2, for example... Figure 3 As shown, in Figure 3 In this process, the pump collimating lens 1-2 is used to collimate the pump light generated by the pump source 1-1 to obtain collimated pump light. The pump collimating lens 1-2 can be a spherical plano-convex lens.

[0109] It should be understood that Figure 2 The working distance of the distributed resonant cavity laser 200 shown This refers to the distance along the optical axis between the gain medium 1-9 in laser emitter 1 and laser receiver 2. When the laser structure is as follows... Figure 2 As shown, when the laser transmitter 1 has only one first cat's-eye structure and the laser receiver 2 has only one second cat's-eye structure, the working distance can be understood as the distance between the gain medium 1-9 and the second lens 2-1 along the optical axis. When the distributed resonator also includes other cat's-eye structures, but only one gain medium exists, the working distance... This should be understood as the distance along the optical axis between the gain medium and the first element following it, viewed from the direction of laser emission. When the distributed resonator also includes other cat's-eye structures and multiple gain media are present, this working distance... It should be understood as the distance along the optical axis between the last element at the emitting end of the laser and the first element at the receiving end of the laser, viewed along the direction of laser emission.

[0110] Based on the above analysis, in order to solve the above-mentioned problems... Figure 1 To address the problems identified in the analysis, enabling distributed resonant cavity lasers to operate efficiently over longer working distances and achieve optimal and stable output power, this application provides a second cat's-eye structure with a cat's-eye constant. The following relationship must be satisfied: (1) In the formula, A, B, C, D, and f are intermediate quantities introduced to simplify the expression of the formula. A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity .

[0111] in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflecting mirror and the first lens. The focal length of the first lens. The focal length of the second lens. The focal length of the thermal lens is the gain medium. The wavelength of the laser. The radius of the laser spot at the first set of reflectors 1-7.

[0112] It should be noted that when the above formula (1) is used to calculate... At that time, the design requirements can be given. and working distance Thus, the calculation is obtained Of course, the above formula (1) can also be used to calculate any distance in the formula.

[0113] Based on the above formula, it can be seen that the distributed resonant cavity laser provided in this application embodiment allows the cat-eye constant of the first cat-eye structure to be different from the focal length of the first lens 1-8, and also allows the cat-eye constant of the second cat-eye structure to be different from the focal length of the second lens 2-1. That is, based on the design of the distributed resonant cavity laser of this application, an asymmetric laser emitting end is allowed, making the design of the laser's structural parameters more flexible. In addition, based on the formula (1) provided in this application embodiment, the relationship between the distances of each segment of the distributed resonant cavity laser can be clearly defined, thereby compensating for the influence of the thermal lens response in the laser gain medium on the retroreflection effect of the cat-eye structure, enabling the laser to achieve a wide range of adjustment-free operation. At the same time, considering that the beam at the receiving end has a certain divergence angle, this formula (1) can optimize the distance between the receiving end lens and the reflector, thereby optimizing the working distance range of the laser.

[0114] Furthermore, considering Figure 2The beam between the first lens 1-8 in the first cat's-eye structure and the second lens 2-1 in the second cat's-eye structure of the distributed resonant cavity laser shown is a collimated Gaussian beam with a large spot size. Therefore, if the first lens 1-8 and the second lens 2-1 are spherical lenses, spherical aberration may occur. The central and peripheral rays of the beam passing through the first lens 1-8 and the second lens 2-1 cannot converge at the same focal point. This will cause some rays to fail to be reflected back, resulting in energy loss and a decrease in the laser's power.

[0115] Therefore, in this embodiment of the application, the maximum range of the absolute value of the spherical difference at the first cat's eye structure and the second cat's eye structure can be calculated by the following formula (2): (2) It should be noted that the absolute value of the spherical difference at the first and second cat's-eye structures should be less than or equal to 2. .

[0116] In general, spherical aberration and field curvature exist in optical systems and need to be corrected simultaneously. When the beam is off-axis, i.e., when the beam is not parallel to the incident beam, field curvature will also cause defocusing. When the defocusing amount exceeds the stable range, the laser will not work, which will limit the field of view of the transmitter and receiver. Therefore, this application embodiment also provides the maximum range of the absolute value of the field curvature of the distributed resonant cavity laser. According to formula (2), the absolute value of the field curvature should not exceed .

[0117] Based on the above formula (2), the distributed resonant cavity laser provided in this application embodiment can compensate for the influence of spherical aberration and field curvature on the retroreflection effect of the cat's eye optical structure, thereby achieving the purpose of optimizing the efficiency, working distance and field of view of the laser.

[0118] Figure 4 A schematic diagram of a distributed resonant cavity laser 400 provided in an embodiment of this application is shown. Figure 4 As shown, the distributed resonant cavity laser 400 may include a laser emitter 1 and a laser receiver 2.

[0119] The laser emitter 1 is composed of a pump source 1-1, a third dichroic mirror 1-3, a third lens 1-4, a gain medium 1-5, a fourth lens 1-6, a first partial reflector 1-7, and a first lens 1-8. The first partial reflector 1-7 and the first lens 1-8 form a first cat's eye structure, the third dichroic mirror 1-3 and the third lens 1-4 form a third cat's eye structure, and the fourth lens 1-6 and the first partial reflector 1-7 form a fourth cat's eye structure.

[0120] The functions of each component are as follows: Pump source 1-1 is used to obtain pump light. For example, pump source 1-1 can be an 808nm fiber-coupled output semiconductor laser or other lasers used to generate pump light.

[0121] The third cat's-eye structure obtains the first optical signal based on the aforementioned pump light. The cat's-eye constant of the third cat's-eye structure is... , The absolute value is the distance between the third dichroic mirror 1-3 and the third lens 1-4.

[0122] Gain media 1-5 are used to obtain a second optical signal using the first optical signal described above. This gain medium can be an a-cut yttrium-doped neodymium vanadate (Nd:YVO4) crystal with a doping concentration of 0.5% and a size of 4×4×4 mm3, which can generate a laser with a wavelength of 1064 nm or the same gain. Of course, the gain medium 1-5 can also be other gain crystals, which are not limited in this application.

[0123] It should be understood that after the gain medium 1-5 receives the first optical signal output by the third cat's eye structure, due to the principle of stimulated emission, the gain medium 1-5 generates a population inversion, that is, a large number of particles are pumped from the ground state to a high energy level. Since the particles at the high energy level are not in a stable state, a second optical signal is generated when the high energy level particles return to the ground state.

[0124] The fourth cat's-eye structure processes the second optical signal to obtain the third optical signal. The cat's-eye constant of the fourth cat's-eye structure is... , The absolute value is the distance between the fourth lens 1-6 and the first set of reflecting mirrors 1-7.

[0125] The first cat's eye structure obtains the fourth optical signal based on the third optical signal. The cat's eye constant of the first cat's eye structure is... , The absolute value is the distance between the first part of the reflecting mirror 1-7 and the first lens 1-8.

[0126] It should be noted that, in Figure 4 The fourth cat's-eye structure can share a partial reflector with the first cat's-eye structure, which allows for a more compact laser structure. Of course, the fourth partial reflector of the fourth cat's-eye structure can differ from the first partial reflector in the first cat's-eye structure; this application does not limit this.

[0127] Furthermore, regarding the working principle of the cat's eye structure mentioned above... Figure 2 as well as Figure 3 A brief explanation has already been given, and for the sake of simplicity, it will not be repeated here.

[0128] The laser receiver 2 includes a second cat's eye structure, which includes a second lens 2-1 and a second part of a reflector 2-2.

[0129] The second cat's eye structure obtains the fifth light signal based on the fourth light signal, and the cat's eye constant of the second cat's eye structure is: , The absolute value is the distance between the second lens 2-1 and the second partial mirror 2-2.

[0130] Optionally, the laser emitting end of the laser 200 may further include pump collimating lenses 1-2, for example... Figure 5 As shown, in Figure 3 In this process, the pump collimating lens 1-2 is used to collimate the pump light generated by the pump source 1-1 to obtain collimated pump light. The pump collimating lens 1-2 can be a spherical plano-convex lens.

[0131] It should be noted that, in Figure 4 The distributed resonant cavity laser 400 shown may also contain other cat's-eye structures, which are not limited in this application. For example, it may be... Figure 6 The structure of the distributed resonant cavity laser 600 is shown. Alternatively, a receiving cat's-eye structure can be added before the third cat's-eye structure to form a bidirectional receiver, as shown below. Figure 7 As shown. Alternatively, a receiving peephole structure can be placed after the first peephole structure, for example... Figure 8 The distributed laser shown, in Figure 8 In the distributed laser shown, when one receiver is in operation, the other receiver can be turned off first. Furthermore, other lasers with novel structures resulting from equivalent deformation should also be within the scope of protection of this application. Therefore, it should be emphasized that the first cat's-eye structure described above is the last cat's-eye structure of the laser transmitter, that is, the second cat's-eye structure is the last cat's-eye structure of the laser receiver.

[0132] It should be understood that, in the embodiments of this application, the first cat-eye structure is located between the fourth cat-eye structure and the second cat-eye structure, such as... Figure 4 As shown, along the laser emission direction, when a beam of light is emitted from right to left, it first passes through the third cat's eye structure, reaches the gain medium, then passes through the fourth cat's eye structure and reaches the first cat's eye structure, and finally exits from the second cat's eye structure.

[0133] It should be understood that Figure 4 The working distance of the distributed resonant cavity laser 400 shown Let be the distance along the optical axis between laser emitter 1 and laser receiver 2. When the laser structure is as follows... Figure 4As shown, this working distance can be understood as the distance between the first lens 1-8 and the second lens 2-1 along the optical axis. When there are multiple receiving ends, the receiving distance of the other ends can be referenced. Figure 4 The regulations already in place will not be repeated here.

[0134] exist Figure 4 In the distributed resonant cavity laser 400 shown, the cat's eye constant of the second cat's eye structure satisfy: (3) In the formula, A, B, C, D, and f are intermediate quantities introduced to simplify the expression of the formula, and the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity .

[0135] in, The absolute value of is the working distance of the laser. The absolute value is the distance between the fourth lens and the first set of reflecting mirrors. The absolute value is the distance between the first lens and the first partial mirror. The absolute value is the distance between the fourth lens and the gain medium. The focal length of the fourth lens. The focal length of the first lens. The focal length of the second lens. The focal length of the thermal lens is the gain medium. The wavelength of the laser. The radius of the laser spot at the first set of reflectors 1-7.

[0136] It should be noted that when the above formula (3) is used to calculate... At that time, it can be given according to the design requirements. and working distance Thus, the calculation is obtained Of course, the above formula (3) can also be used to calculate any distance in the formula.

[0137] The distributed resonant cavity laser designed based on the above formula (3) makes the cat's eye constant of the cat's eye structure no longer strictly equal to the lens focal length, which increases the flexibility of laser design and enables large-scale adjustment-free operation. Considering that the beam at the receiving end has a certain divergence angle, the formula (3) can optimize the distance between the receiving end lens and the reflector, thereby optimizing the working distance range of the laser.

[0138] Furthermore, considering Figure 4The beam between the first lens 1-8 in the first cat's-eye structure and the second lens 2-1 in the second cat's-eye structure of the distributed resonant cavity laser shown is a collimated Gaussian beam with a large spot size. Therefore, if the first lens 1-8 and the second lens 2-1 are spherical lenses, spherical aberration may occur. The central and peripheral rays of the beam passing through the first lens 1-8 and the second lens 2-1 cannot converge at the same focal point. This will cause some rays to fail to be reflected back, resulting in energy loss and a decrease in the laser's power.

[0139] Therefore, in this embodiment of the application, the maximum range of absolute values ​​of spherical aberration and field curvature at all spherical lenses inside the first cat's-eye structure, the second cat's-eye structure, and the transmitter should also refer to the relationship shown in formula (2). That is, the spherical aberration at all spherical lenses inside the first cat's-eye structure, the second cat's-eye structure, and the transmitter should be less than or equal to 2. The value of the performance should not exceed .

[0140] Based on the above solution, the distributed resonant cavity laser provided in this application embodiment can compensate for the influence of spherical aberration and field curvature on the retroreflection effect of the cat's eye optical structure, thereby achieving the purpose of optimizing the laser's efficiency, working distance, and field of view.

[0141] It should be understood that Figure 4 The laser shown can also have a second gain medium 1-9 placed at the exit pupil position of the first cat's eye structure of the laser, for example... Figure 9 The structure shown indicates that the gain medium 1-9 can further improve the laser gain and stabilize the output power of the laser.

[0142] Furthermore, in this application Figure 4 In the laser 400 shown, the fourth cat's eye constant satisfy: (4) In the formula, , Intermediate quantities are introduced to simplify the expression of formulas. satisfy: intermediate quantity satisfy: ,in, The absolute value is the distance from the third lens to the gain medium. This is the focal length of the third lens mentioned above.

[0143] As can be seen from formula (4), the focal lengths of the third lens 1-4 and the fourth lens 1-6 can be the same or different. This is because the laser gain medium 1-5 contains a thermal lens. The function of the distance between the lens and the mirror in the third and fourth cat's-eye structures. and It doesn't have to be equal to the focal length of each individual lens; instead, it can be compensated for according to the above relationship. By selecting one value based on the structural design requirements and then determining the other using the above relationship, the structural design of lasers is facilitated.

[0144] It should be noted that formula (4) above represents the fourth cat's eye constant in practical applications. The range can be the ideal value within a deviation. Within the range of left and right, this fourth cat's eye constant The ideal value is calculated using the following formula (5), and the deviation is... Calculated using the following formula (6).

[0145] (5) (6) In equation (7), a, b, c, d, e, and f are intermediate quantities introduced to simplify the expression of the formula. satisfy: intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: .

[0146] That is, equations (4) to (6) above are to illustrate that, in actual work, the relationship between the above parameters may not precisely satisfy the equation in (5), when the distance between the fourth lens 1-6 and the first part of the reflecting mirror 1-7... There is a deviation from the ideal value obtained according to equation (5). At that time, the parameters of each cavity should satisfy the relationship of equation (6).

[0147] Based on the above scheme, the distributed resonant cavity laser provided in this application embodiment allows the cat's eye structure inside the transmitter to not strictly follow the demanding condition that the reflector needs to be placed at the focal plane of the lens, but allows for the design of an asymmetrical cat's eye structure in the transmitter part, making the design of the laser's structural parameters more flexible.

[0148] The above, combined with Figures 2 to 9 The present application provides a detailed description of the possible structures of the distributed resonant cavity laser provided in its embodiments. The following, in conjunction with... Figures 10 to 12This application provides a detailed description of the method for generating laser light.

[0149] Figure 10 A schematic block diagram of a method 1000 for amplifying optical signals according to an embodiment of this application is shown. The distributed cavity laser corresponding to this method 1000 can be referred to... Figure 2 The laser shown may include a laser emitter 1 and a laser receiver 2.

[0150] The laser emitter 1 consists of a pump source 1-1, a first part of the reflector 1-7, a first lens 1-8, and a gain medium 1-9, wherein the first part of the reflector 1-7 and the first lens 1-8 constitute a first cat's eye structure.

[0151] The laser receiver 2 includes a second cat's eye structure, which includes a second lens 2-1 and a second part of a reflector 2-2.

[0152] like Figure 10 As shown, the method specifically includes: S1001, acquire pump light.

[0153] Specifically, pump light is obtained using pump source 1-1. Pump source 1-1 can be an 808nm fiber-coupled output semiconductor laser, which can output 808nm laser light as pump light input to the emitter of distributed resonant cavity laser 200.

[0154] S1002, the first optical signal is obtained based on the pump light.

[0155] Specifically, the first cat's eye structure obtains the second optical signal based on the pump light mentioned above. The first cat's eye structure is the last cat's eye structure at the laser emitting end of the laser, that is, the first cat's eye structure is the last cat's eye structure before the gain medium in the laser. The first cat's eye structure includes a first part of the reflector 1-7 and a first lens 1-8.

[0156] It should be understood that, in the embodiments of this application, the first cat's-eye structure is the last cat's-eye structure before the gain medium in the laser, meaning that along the laser emission direction, such as... Figure 2 As shown, viewed from right to left, the first cat's eye structure is in front of the gain medium, meaning that the pump light emitted from the pump source will first pass through the first cat's eye structure before reaching the gain medium.

[0157] Optionally, before processing the pump light by the first cat's-eye structure, the method may further include collimating the pump light, specifically, by collimating the pump light generated by the pump source using a collimating lens. In this case, the first cat's-eye structure obtains a first optical signal based on the collimated pump light.

[0158] S1003, the second optical signal is obtained using the first optical signal.

[0159] Specifically, gain media 1-9 are used to obtain the second optical signal from the first optical signal described above. These gain media 1-9 can be α-cut neodymium-doped yttrium vanadate (Nd:YVO4) crystals with a doping concentration of 0.5% and dimensions of 4×4×4 mm. 3 This allows the generation of lasers with a wavelength of 1064nm, or other types of laser gain crystals.

[0160] The working principle of the gain dielectric 1-9 can be found in [reference]. Figure 2 For the sake of simplicity, the description in the text will not be repeated here.

[0161] S1004, the third optical signal is obtained based on the second optical signal.

[0162] Specifically, the second cat's-eye structure obtains a third optical signal based on the second optical signal, and the cat's-eye constant of the second cat's-eye structure is: , The absolute value is the distance between the second lens 2-1 and the second partial mirror 2-2.

[0163] The cat's eye constant of the second cat's eye structure The following relationship must be satisfied: (1) In the formula, A, B, C, D, and f are intermediate quantities introduced to simplify the expression of the formula, and the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflecting mirror and the first lens. The focal length of the first lens. The focal length of the second lens. The focal length of the thermal lens is the gain medium. The wavelength of the laser. The radius of the laser spot at the first set of reflectors 1-7.

[0164] It should be noted that the working distance of the laser mentioned above is the distance from the gain medium 1-9 to the laser receiver end of the laser along the optical axis. Specifically, it can be the distance from the gain medium 1-9 to the second part of the reflector 2-2 along the optical axis.

[0165] It should be noted that when the above formula (1) is used to calculate... At that time, the design requirements can be given. and working distance Thus, the calculation is obtained Of course, the above formula (1) can also be used to calculate any distance in the formula.

[0166] Based on the above formula, it can be seen that in the laser generation method provided in this application embodiment, the cat's eye constant of the first cat's eye structure is not equal to the focal length of the first lens 1-8, and the cat's eye constant of the second cat's eye structure is not equal to the focal length of the second lens 2-1. That is, asymmetric laser emitting end is allowed, making the design of laser structural parameters more flexible. In addition, based on the formula (1) provided in this application embodiment, the relationship between the distances of each segment of the distributed resonant cavity laser can be clearly defined, thereby compensating for the influence of the thermal lens response in the laser gain medium on the retroreflection effect of the cat's eye structure, enabling the laser to achieve large-range adjustment-free operation. At the same time, considering that the beam at the receiving end has a certain divergence angle, this formula (1) can optimize the distance between the receiving end lens and the reflector, thereby optimizing the working distance range of the laser.

[0167] It should be noted that the working principles of the above-mentioned cat-eye structures can be found by referring to... Figure 2 For the sake of simplicity, the description in the text will not be repeated here.

[0168] Furthermore, in order to further correct the spherical aberration and field curvature of the system, the maximum range of the absolute value of the spherical aberration at the first cat's-eye structure and the second cat's-eye structure can be calculated by formula (2) as shown below: (2) It should be noted that the absolute value of the spherical difference at the first and second cat's-eye structures should be less than or equal to 2. The absolute value of the performance should not exceed .

[0169] Based on the above formula (2), the laser generation method provided in this application embodiment can compensate for the influence of spherical aberration and field curvature on the retroreflection effect of the cat's eye optical structure, thereby achieving the purpose of optimizing the efficiency, working distance and field of view of the laser.

[0170] Figure 11 A schematic block diagram of a method 1100 for amplifying optical signals according to an embodiment of this application is shown. The distributed cavity laser corresponding to this method 1100 can be referred to... Figure 4 The laser shown may include a laser emitter 1 and a laser receiver 2.

[0171] The laser emitter 1 is composed of a pump source 1-1, a third dichroic mirror 1-3, a third lens 1-4, a gain medium 1-5, a fourth lens 1-6, a first partial reflector 1-7, and a first lens 1-8. The first partial reflector 1-7 and the first lens 1-8 form a first cat's eye structure, the third dichroic mirror 1-3 and the third lens 1-4 form a third cat's eye structure, and the fourth lens 1-6 and the first partial reflector 1-7 form a fourth cat's eye structure.

[0172] The laser receiver 2 includes a second cat's eye structure, which includes a second lens 2-1 and a second part of a reflector 2-2.

[0173] like Figure 11 As shown, the method specifically includes: S1101, acquire pump light.

[0174] Specifically, pump light is obtained using pump source 1-1. Pump source 1-1 can be an 808nm fiber-coupled output semiconductor laser, which can output 808nm laser light as pump light input to the emitter of distributed resonant cavity laser 200.

[0175] S1102, the first optical signal is obtained based on the pump light.

[0176] Specifically, the third cat's-eye structure obtains the first optical signal based on collimated pump light. The cat's-eye constant of the third cat's-eye structure is... , The absolute value is the distance between the third dichroic mirror 1-3 and the third lens 1-4.

[0177] Optionally, before the third cat's eye processes the pump light, the method may further include collimating the pump light. Specifically, the pump light generated by the pump source 1-1 may be collimated using a pump collimating lens to obtain collimated pump light. This pump collimating lens may be a spherical plano-convex lens. In this case, the third cat's eye obtains a first optical signal based on the collimated pump light.

[0178] S1103, using the first optical signal to obtain the second optical signal.

[0179] Specifically, the gain medium 1-5 is used to obtain the first optical signal using the collimated pump laser described above. This gain medium 1-5 can be an α-cut neodymium-doped yttrium vanadate (Nd:YVO4) crystal with a doping concentration of 0.5% and a size of 4×4×4 mm. 3 This allows the generation of lasers with a wavelength of 1164nm, or other types of laser gain crystals.

[0180] The working principle of the gain medium 1-5 can be found in [reference]. Figure 2 or Figure 3 Figure 4 For the sake of simplicity, the description in the text will not be repeated here.

[0181] S1104, the second optical signal is processed to obtain the third optical signal.

[0182] Specifically, the fourth cat's-eye structure processes the second optical signal to obtain the third optical signal. The cat's-eye constant of the fourth cat's-eye structure is... , The absolute value is the distance between the fourth lens 1-6 and the first set of reflecting mirrors 1-7.

[0183] S1105, the fourth optical signal is obtained based on the third optical signal.

[0184] Specifically, the first cat's eye structure obtains the fourth optical signal based on the third optical signal. The cat's eye constant of the first cat's eye structure is... , The absolute value is the distance between the first part of the reflecting mirror 1-7 and the first lens 1-8.

[0185] It should be noted that the fourth cat's-eye structure can share a partial reflector with the first cat's-eye structure, which allows for a more compact laser structure. Of course, the fourth partial reflector of the fourth cat's-eye structure can differ from the first partial reflector in the first cat's-eye structure; this application does not limit this.

[0186] Furthermore, the working principle of the cat's eye structure has been briefly explained in the corresponding section above, and for the sake of simplicity, it will not be repeated here.

[0187] S1106, the third optical signal is obtained based on the fourth optical signal.

[0188] Specifically, the second cat's eye structure obtains the fifth light signal based on the fourth light signal, and the cat's eye constant of the second cat's eye structure is: , The absolute value is the distance between the second lens 2-1 and the second partial mirror 2-2.

[0189] Among them, the cat-eye constant of the second cat-eye structure The following relationship must be satisfied: (3) In the formula, A, B, C, D, and f are intermediate quantities introduced to simplify the expression of the formula, and the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity .

[0190] in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first lens and the first part of the reflecting mirror. The focal length of the first lens. The focal length of the second lens. The focal length of the thermal lens is the gain medium. The wavelength of the laser. The radius of the laser spot at the first set of reflectors 1-7.

[0191] It should be understood that, in the embodiments of this application, the first cat-eye structure is located between the fourth cat-eye structure and the second cat-eye structure, such as... Figure 4 As shown, along the laser emission direction, when a beam of light is emitted from right to left, it first passes through the third cat's eye structure, reaches the gain medium, then passes through the fourth cat's eye structure and reaches the first cat's eye structure, and finally exits from the second cat's eye structure.

[0192] In this embodiment of the application, the working distance Let be the distance along the optical axis between laser emitter 1 and laser receiver 2. When the laser structure is as follows... Figure 4 As shown, the working distance can be understood as the distance between the first lens 1-8 and the second lens 2-1 along the optical axis.

[0193] It should be noted that when the above formula (3) is used to calculate... At that time, it can be given according to the design requirements. And working distance, thus calculating Of course, the above formula (3) can also be used to calculate any distance in the formula.

[0194] The distributed resonant cavity laser designed based on the above formula (3) makes the cat's eye constant of the cat's eye structure no longer strictly equal to the lens focal length, which increases the flexibility of laser design and enables large-scale adjustment-free operation. Considering that the beam at the receiving end has a certain divergence angle, the formula (3) can optimize the distance between the receiving end lens and the reflector, thereby optimizing the working distance range of the laser.

[0195] Furthermore, in order to further correct the spherical aberration and field curvature of the system, the maximum range of the absolute value of the spherical aberration at the first cat's-eye structure and the second cat's-eye structure can be calculated by formula (2) as shown below: (2) It should be noted that the absolute value of the spherical difference at the first and second cat's-eye structures should be less than or equal to 2. The absolute value of the performance should not exceed .

[0196] Based on the above formula (2), the laser generation method provided in this application embodiment can compensate for the influence of spherical aberration and field curvature on the retroreflection effect of the cat's eye optical structure, thereby achieving the purpose of optimizing the efficiency, working distance and field of view of the laser.

[0197] It should be noted that the working principles of the above-mentioned cat-eye structures can be found by referring to... Figure 2 or Figure 3 For the sake of simplicity, the description in the text will not be repeated here.

[0198] Among them, the fourth cat's eye constant satisfy: (4) In the formula, , Intermediate quantities are introduced to simplify the expression of formulas. satisfy: intermediate quantity satisfy: ,in, The absolute value is the distance from the third lens to the gain medium. This is the focal length of the third lens mentioned above.

[0199] As can be seen from formula (5), the focal lengths of the third lens 1-4 and the fourth lens 1-6 can be the same or different. This is because the laser gain medium 1-5 contains a thermal lens. The function of the distance between the lens and the mirror in the third and fourth cat's-eye structures. and It doesn't have to be equal to the focal length of each individual lens; instead, it can be compensated for according to the above relationship. By selecting one value based on the structural design requirements and then determining the other using the above relationship, the structural design of lasers is facilitated.

[0200] It should be noted that this fourth cat's eye constant The ideal value is calculated using the following formula (5), and the deviation is... Calculated using the following formula (6).

[0201] (5) (6) In equation (7), a, b, c, d, e, and f are intermediate quantities introduced to simplify the expression of the formula. satisfy: intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: .

[0202] According to the above formula, in actual work, the relationship between the above parameters may not precisely satisfy the equation in (5). When the distance between the fourth lens 1-6 and the first part of the reflecting mirror 1-7... There is a deviation from the ideal value obtained according to equation (5). At that time, the parameters of each cavity should satisfy the relationship of equation (6).

[0203] Based on the above scheme, the distributed resonant cavity laser provided in this application embodiment allows the cat's eye structure inside the transmitter to not strictly follow the demanding condition that the reflector needs to be placed at the focal plane of the lens, but allows for the design of an asymmetrical cat's eye structure in the transmitter part, making the design of the laser's structural parameters more flexible.

[0204] The above, combined with Figures 2 to 11 This application provides a detailed description of the distributed resonant cavity laser and the method for generating laser light, based on embodiments thereof. The following description, in conjunction with… Figure 1 or Figure 4 The design concept of the distributed resonant cavity laser is shown, and the different characteristics of the distributed laser provided by specific embodiments under different parameter values ​​are explained in detail.

[0205] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The diagram shows a distributed cavity laser. This distributed cavity laser includes a laser emitter 1 and a laser receiver 2. The laser emitter 1 consists of a pump source 1-1, a pump collimating lens 1-2, a laser total reflection mirror 1-3, a first intracavity lens 1-4, a laser gain medium 1-5, a second intracavity lens 1-6, an intracavity partial reflector 1-7, and a third intracavity lens 1-8. The laser receiver 2 consists of a fourth intracavity lens 2-1 and a laser output mirror 2-2. The distances between the components are shown in the diagram. - Logo.

[0206] Pump source 1-1 is an 808nm fiber-coupled semiconductor laser, and laser gain medium 1-5 is an a-cut Nd:YVO4 crystal with a doping concentration of 0.5% and a size of 4×4×4mm. 3The laser wavelength is 1064nm. Pump collimating lenses 1-2 are spherical plano-convex lenses with a focal length of 10mm. The first cavity lens 1-4 and the second cavity lens 1-6 are both aspherical plano-convex lenses with an f=24.6mm focal length. The third cavity lens 1-8 is an aspherical plano-convex lens with an f=48.3mm focal length. Their surface shapes are shown in the attached figures. Figure 12 and attached Figure 13 As shown, the Figure 12 and Figure 13 Aspherical lenses can be used to replace spherical lenses, with the most significant advantage being their ability to correct spherical aberration introduced by spherical lenses in collimation and focusing systems. By adjusting the surface constant and aspherical coefficient, aspherical lenses can eliminate spherical aberration to a maximum extent. Figure 12 In this example, the radius of curvature of the aspherical surface of the aspherical lens is 12.465 mm, the diameter is approximately 12.7 mm, the thickness is approximately 5 mm, and the surface roughness of the lens is approximately 6.4 μm. Figure 13 In this design, the radius of curvature of the aspherical surface of the aspherical lens is 24.489 mm, its diameter is approximately 20 mm, its thickness is approximately 5 mm, and its surface roughness is approximately 6.4 μm. The fourth intracavity lens 2-1 is a spherical plano-convex lens with a focal length f = 51.8 mm. The pump collimating lens 1-2, the laser total reflection mirror 1-3, the first intracavity lens 1-4, and the laser gain medium 1-5 are coated with an 808 nm antireflection film. The pump source output from the fiber coupling is collimated and focused before entering the laser crystal, and the pump spot radius is approximately 500 μm. The first intracavity lens 1-4, the laser gain medium 1-5, the second intracavity lens 1-6, the third intracavity lens 1-8, and the fourth intracavity lens 2-1 are coated with a 1064nm laser wavelength antireflection film. The laser total reflection mirror 1-3 is also coated with a 1064nm high reflectivity film. The intracavity partial reflector 1-7 is coated with a 1064nm partial reflectivity film with an R=20%. The laser output mirror 2-2 is coated with a 1064nm partial reflectivity film with an R=50%. The etalon effect formed by the intracavity partial reflector 1-7 and the laser output mirror 2-2 together provides the laser with an equivalent positive feedback of approximately 77% R.

[0207] When the laser operates within its stable region, once the pump power exceeds the laser threshold, the laser oscillates within a distributed laser resonant cavity comprised of the laser total reflection mirror 1-3 and the laser output mirror 2-2, and is output through the laser output mirror 2-2. The focal length ratio of the second intracavity lens 1-6 to the third intracavity lens 1-8 is approximately 1:2, which serves to expand the beam and increase the Rayleigh distance. The laser spot size at the fourth intracavity lens 2-1 varies with the operating distance. change, When the distance is increased from 0.5m to 5m, the radius of the light spot at lens 2-1 increases from approximately 1mm to approximately 2mm.

[0208] When the pump power is 10W, the focal length of the thermal lenses in laser gain media 1-5 is approximately 500mm, and the distances between the devices are L1=24.0mm, L2=19.5mm, L3=19.5mm, L4=24.0mm, and L5=47.1mm. That is, as described in formula (4) in the above specification, the distance between the lens and the reflector in the third and fourth cat's-eye structures is not equal to the focal length of the lens, but is less than the focal length of the lens, satisfying the aforementioned relationship, so that the beam focused by the crystal thermal lensing effect can be reflected back. Under this condition, the distributed resonant cavity laser can obtain a continuous wave output power of more than 2W within a working distance range of 1-5m, and has a certain adjustment-free working range.

[0209] When the pump power is 16W, the focal length of the thermal lens in the laser gain medium 1-5 is further shortened to about 300mm. At this time, according to formula (4), the preferred experimental conditions are L1=23.6mm and L4=23.6mm, instead of the focal length of the lens of 24.8mm. It is possible to obtain an output power of more than 4W within a working distance range of 1-5m.

[0210] As can be seen in this specific embodiment, the distributed resonant cavity laser designed according to the design method provided in this application can stably output power with fluctuations not exceeding 20% ​​of the peak value.

[0211] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser is shown. When the focal lengths of the first intracavity lens 1-4 and the second intracavity lens 1-6 become 56.1 mm, and the focal length of the third intracavity lens 1-8 becomes 100 mm, according to the above relationship (3), when the pump power is 10 W, the pump spot radius is 500 μm, and the thermal lens focal length is 500 mm, an output power of more than 2 W can be obtained when L1=L4=52.96 mm. When the pump power is 16 W, the pump spot radius is 500 μm, and the thermal lens focal length is 300 mm, an output power of more than 4 W can be obtained when L1=L4=50.87 mm. At this time, it can be seen that the distance between the lens and the reflector in the third cat's eye structure and the fourth cat's eye structure is not equal to the lens focal length.

[0212] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser shown. When selecting... and Even with unequal parameter combinations, as long as the sum of the two satisfies the value determined by formula (4), given the focal length of the lens and the focal length of the thermal lens, the laser can be guaranteed to have a high conversion efficiency within a certain adjustment-free operating range. For example, when the focal lengths of the first intracavity lens 1-4 and the second intracavity lens 1-6 are 56.1 mm and the focal length of the third intracavity lens 1-8 is 100 mm, with a pump power of 10 W, a pump spot radius of 500 μm, and a thermal lens focal length of 500 mm, L1 = 30 mm and L4 = 75.92 mm can be set, which can also allow the inner cavity part to achieve a good inverse reflection effect as a whole. Based on formula (4), the limitation that the reflector of the cat's eye structure must be placed at the focal point of the lens is eliminated, making the structural design of the laser more flexible.

[0213] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser shown is preferably designed for use when the focal length of the fourth intracavity lens 2-2 at the receiving end is 51.8 mm. The range is 52.3-52.6 mm, which is due to the inherent divergence characteristics of Gaussian beams mentioned earlier. It should be slightly larger than the focal length of the fourth cavity lens 2-2. At this point, under 10W and 16W pumping, it can maintain an output power of over 2W and 4W respectively within a working distance range of 0.5m-5m. When Beyond this range, good power characteristics cannot be maintained across the entire operating distance. In other words, to achieve a large adjustment-free operating range, the distance between the receiving lens and the output lens should be slightly greater than the focal length of the lens.

[0214] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser shown above. Regardless of whether a commonly used plane mirror or a concave mirror with a radius of curvature (ROC) similar to the lens focal length is chosen as the laser output mirror 2-2, severe field curvature will occur, limiting the field of view at the receiver.

[0215] At a pump power of 16W and a pump spot radius of 500μm, for the fourth intracavity lens 2-1 with f=51.8mm, using a planar output mirror and a concave output mirror with ROC=51.8mm, the laser can no longer emit light at a working distance of 2m when the field of view at the receiver exceeds ±3° and ±6°, respectively. At this point, the defocusing caused by field curvature is 0.34D and 0.28D, respectively. When the working distance is further increased, the field of view decreases further due to the narrowing of the stable region. However, if a concave reflector with ROC=77.26mm, i.e., a standard plano-concave lens with a focal length of -150mm, is selected as the laser output mirror 2-2, a good match between its field curvature image plane and the reflecting surface can be achieved, as shown in the attached diagram. Figure 14 and Figure 15 The field curvature calculation results for laser output mirror 2-2 with ROC values ​​of 51.8 mm and 77.26 mm are presented respectively, thus significantly optimizing the field of view at the receiver. When this parameter combination is used, the laser output power is more than 80% of its maximum normal incident output power within a ±20° receiver field of view angle range at a working distance of 5 m.

[0216] Furthermore, other combinations of lens focal lengths and mirror curvature radii can be used to correct field curvature and optimize the receiver's field of view. For example, a combination of a fourth intracavity lens 2-1 with f=33.9mm and a laser output mirror 2-2 with ROC=51.8 mm can be used. For instance, when using a laser output mirror 2-2 with a diameter of 25.4mm, the laser output power can be maintained at more than 80% of its maximum normal incident output power within a ±20° receiver field of view at a working distance of 5m. This results in smaller device size and spacing, which is beneficial for optimizing the volume of the laser receiver.

[0217] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The diagram shows a distributed resonant cavity laser. At long operating distances, the laser spot size at the fourth cavity lens 2-1 becomes relatively large, resulting in spherical aberration. Spherical aberration causes the actual focal points of the edge rays and the center rays of the beam to differ. When reflected by the laser output mirror 2-2, some energy is always not ideally reflected back. Therefore, with the presence of spherical aberration, the laser output power decreases as the operating distance increases.

[0218] To address this issue, one approach is to use an aspherical lens with corrected spherical aberration as the fourth intracavity lens 2-1. Alternatively, a lens with a larger focal length and higher refractive index can be used as the fourth intracavity lens 2-1 to optimize the laser's working distance.

[0219] Appendix Figure 16 The four curves from top to bottom show the results using an aberration-free aspherical lens (f=25mm), a spherical lens (f=56.1mm), a spherical lens (f=33.9mm), and a spherical lens (f=15mm). It can be seen that when using the aberration-free aspherical lens (f=25mm) and the spherical lens (f=56.1mm) as lenses 2-1 in the second cat's-eye structure, relatively ideal output power can be obtained at longer working distances. However, when using the smaller focal lengths of the spherical lenses (f=33.9mm and f=15mm), the power decreases significantly due to the larger spherical aberration caused by the large spot size at long working distances.

[0220] This embodiment illustrates that correcting spherical aberration can optimize the working distance characteristics of a laser.

[0221] In one specific embodiment, reference can be made to Figure 1or Figure 4 The distributed resonant cavity laser is shown. When there is an off-axis amount of the laser receiver relative to the main ray of the laser emitter, the ray is not incident normally relative to the third, fourth, and first cat's-eye structures. At this time, the lenses in each cat's-eye structure of the emitter also have the problem of field curvature. Field curvature causes the actual focal point to deviate from the reflecting surface. Defocusing limits the off-axis amount of the laser receiver, that is, the field of view of the laser emitter.

[0222] To address this issue, a suitable lens focal length and mirror curvature radius can be selected to match the field curvature of the image plane with that of the reflecting surface, achieving a good retroreflection effect. Alternatively, field curvature correction can be implemented through optical design. A positive lens produces positive field curvature, while a negative lens produces negative field curvature; their sum results in a field curvature of 0 or close to 0, achieving a flat field effect. This method of separating positive and negative lenses is commonly used to correct field curvature. However, to reduce the number of lenses, this application example employs aspherical technology to correct field curvature without increasing the number of lenses, thus correcting the image plane to the desired shape.

[0223] The embodiments of this application can adopt a surface type as follows: Figure 12 and attached Figure 13 The aspherical mirror shown is a plano-convex type, where the aspherical surface is the coefficient. The hyperboloid has a Petzval radius to focal length ratio greater than 5, resulting in a very flat image field. Low-melting-point molding glass, such as K9 or ZK3, can be used as the material, facilitating mass production and significantly reducing costs. The first intracavity lens 1-4 and the second intracavity lens 1-6 both use the materials shown in the attached figure. Figure 12 The surface shape, the third intracavity lens 1-8 adopts as shown in the attached figure Figure 13 The surface profiles have focal lengths of 24.6mm and 48.3mm, respectively. The correction for defocusing caused by field curvature in the third and fourth cat's-eye structures of the transmitter is shown in the attached simulation results for the inner cavity. Figure 17 As shown, beams incident through the cat's-eye structure pupil within a certain angle are all incident directly on the reflecting mirror, with the actual focal point located at the reflecting surface. In this embodiment, the half-power field of view of the transmitter, measured at a working distance of 2m, reaches ±3°, while the field of view of the transmitter without field curvature correction is only about ±0.5°, indicating a significant improvement in the field of view. Increasing the order or number of aspherical mirrors can further enhance the improvement. Additionally, using other types of aspherical mirrors, such as biconvex or thick meniscus mirrors, can achieve the same effect. Furthermore, other materials that can be processed using cold working methods can also be selected for the glass material. All of these should be within the scope of protection of this application.

[0224] It should be noted that for the fourth cat-eye structure and the first cat-eye structure, that is, when the internal cavity partial reflector 1-7 is involved, since the internal cavity partial reflector 1-7 needs to provide good retroreflection for light incident from both sides, the image planes of the second cavity lens 1-6 and the third cavity lens 1-8 should be corrected to be planar. For the third cat-eye structure, both of the above implementation methods are acceptable.

[0225] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser shown is illustrated in the above embodiment. Figure 12 and attached Figure 13 The aspherical lens surface designs given for the first intracavity lens 1-4, the second intracavity lens 1-6, and the third intracavity lens 1-8 fully consider the correction of field curvature and spherical aberration. Therefore, the above design can also be used as the fourth intracavity lens 2-1 of the receiver, in conjunction with the planar laser output mirror 2-2 to form a receiver, achieving the effect of optimizing the angle and working distance characteristics of the receiver.

[0226] Using the aforementioned lens that corrects field curvature and spherical aberration as the fourth intracavity lens 2-1 in conjunction with the planar laser output mirror 2-2, the laser output power can be maintained at more than 80% of its maximum value within a working distance of 0.5m-5m and a receiving end field of view of ±12°.

[0227] Based on the above solution, the embodiments of this application can directly use an internal cavity aspherical lens without redesigning the aspherical lens.

[0228] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser shown is illustrated. The receiver can be as shown in the attached diagram. Figure 18 This structure consists of two concentric hemispheres of the same material but different radii, meaning the centers of the two curved surfaces coincide. A key feature of this structure is the absence of a traditional principal optical axis, resulting in minimal field-of-view aberrations—meaning the optical aberrations are identical across different fields of view. Only field-of-view-independent spherical aberrations need correction. It's important to note that the structure's size should not be too small; otherwise, vignetting at the edges of the field of view will reduce edge illumination, leading to energy loss. Therefore, the radius of the smaller hemisphere should be greater than 13mm, while the radius of the larger hemisphere should be between 1.2 and 3 times that of the smaller hemisphere. Most laser applications are single-wavelength applications, eliminating the need to consider chromatic aberration; using the same material for both hemispheres is sufficient. This also avoids the drawbacks of bonding different materials in laser applications, which can easily lead to aging and damage.

[0229] If damage threshold is considered, K9 glass material can be selected. The radius of the left hemisphere is 15mm and the radius of the right hemisphere is 28.75mm, which can achieve correction of field curvature and spherical aberration, both less than 0.1D. In practical applications, considering assembly and volume requirements, the sides can also be processed into a cylindrical shape if the extreme field of view is not required.

[0230] The solution based on the embodiments of this application uses a single device to form the receiving end, resulting in low loss and simple assembly.

[0231] In one specific embodiment, reference can be made to Figure 1 or Figure 4 The distributed resonant cavity laser shown is illustrated. (See attached image.) Figure 19 As shown, with the aperture stop as the boundary, the front part of the lens group is a meniscus lens with a focal length ranging from 100mm to 500mm. Its main function is to correct field curvature and partially contribute to the system's optical power. This meniscus lens can also be replaced by a combination of a plano-convex lens and a plano-concave lens, further reducing manufacturing difficulty. The rear part of the lens group is a plano-convex lens, which mainly contributes to the system's optical power and corrects spherical aberration. This lens can also be a biconvex lens or a combination of multiple lenses.

[0232] In this application example, standard components can be selected to complete the design. For example, the components of this receiver from left to right are Beijing Opto GL11-025-076, Beijing Opto GL13-025-160, Changchun Jinlong 11A1252R, and Beijing Opto GL13-050-063, with distances of 0.1mm, 5.9mm, and 21mm respectively. This design achieves effective field curvature and spherical aberration correction, both less than 0.1D. This structure has a large receiver field of view of ±30°.

[0233] Based on the above solution, in the embodiments of this application, all the devices used are conventional standard devices, which are highly versatile and cost-effective.

[0234] It should be noted that in all the embodiments described above in this application, the laser gain medium can be laser crystals such as Nd:YVO4, Nd:GdVO4 (doped with neodymium gadolinium vanadate), Nd:YAG (doped with neodymium yttrium aluminum garnet), Ti:Sa (doped with titanium sapphire), or commonly used solid-state laser gain media such as laser glass or laser ceramics doped with Nd, Yb (ytterbium), Er (erbium), or other luminescent ions, as well as optically pumped semiconductor gain media, etc. The corresponding pump source wavelength and coating band can correspond to the absorption peak and emission peak of the laser gain medium. It can also be an electrically pumped semiconductor laser gain medium. This application does not limit this.

[0235] The embodiments of this application do not impose specific restrictions on the focal length and surface shape of the optical elements constituting the resonant cavity, as long as field curvature and spherical aberration can be corrected and defocusing of the cat's eye retroreflection structure can be avoided.

[0236] Unless otherwise specified, the model numbers of the various devices in this application embodiment are not limited, and any device that can perform the above functions is acceptable.

[0237] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0238] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application should be included in the protection of this application. The above description is merely a specific implementation of this application, but the protection scope of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A laser, characterized in that, include: Pump source, first cat's-eye structure, gain medium, second cat's-eye structure, in, The pump source is used to acquire pump light. The first cat's-eye structure obtains a first optical signal based on the pump light. The first cat's-eye structure is the last cat's-eye structure before the gain medium. The first cat's-eye structure includes a first lens and a first partial reflector. The gain medium uses the first optical signal to obtain the second optical signal, and the gain medium is placed at the exit pupil position of the first cat's eye structure. The second cat's-eye structure obtains a third optical signal based on the second optical signal. The second cat's-eye structure is the last cat's-eye structure of the laser. The second cat's-eye structure includes a second lens and a second part of a reflector. The cat-eye constant of the second cat-eye structure The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... Satisfaction: In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflector and the first lens. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

2. The laser according to claim 1, characterized in that, The absolute value of the spherical aberration at the first cat's eye structure and / or the second cat's eye structure is less than or equal to 2. ,in, satisfy: 。 3. The laser according to claim 1 or 2, characterized in that, The absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to ,in, satisfy: 。 4. A laser, characterized in that, include: Pump source, third cat's-eye structure, gain medium, fourth cat's-eye structure, first cat's-eye structure, second cat's-eye structure. in, The pump source is used to acquire pump light. The third cat's-eye structure obtains the first optical signal based on the pump light. The third cat's-eye structure is the last cat's-eye structure before the gain medium. The third cat's-eye structure includes a third lens and a third dichroic mirror. The gain medium uses the first optical signal to obtain the second optical signal. The fourth cat's-eye structure processes the second optical signal to obtain the third optical signal. The fourth cat's-eye structure is the first cat's-eye structure after the gain medium. The fourth cat's-eye structure includes a fourth lens and a first part of a reflector. The first cat-eye structure generates a fourth light signal based on the third light signal. The first cat-eye structure is located between the fourth cat-eye structure and the second cat-eye structure. The first cat-eye structure includes a first lens and a first partial reflector. The second cat's-eye structure obtains the fifth optical signal based on the fourth optical signal. The second cat's-eye structure is the last cat's-eye structure of the laser. The second cat's-eye structure includes a second lens and a second part of a reflector. The cat-eye constant of the second cat-eye structure The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... satisfy: In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first lens and the first partial reflector. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

5. The laser according to claim 4, characterized in that, The cat-eye constant of the fourth cat-eye structure satisfy: In the formula, intermediate quantities satisfy: intermediate quantity satisfy: ,in, The absolute value is the distance from the third lens to the gain medium. The focal length of the third lens is... The absolute value of is the cat's eye constant. The deviation from the ideal value, where the ideal value is... , The absolute value is the distance from the third lens to the third dichroic mirror. The absolute value of is the distance from the gain medium to the fourth lens. The focal length of the fourth lens is given.

6. The laser according to claim 5, characterized in that, The The following relationship must be satisfied: In the formula, intermediate quantities satisfy: intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: .

7. The laser according to any one of claims 4 to 6, characterized in that, The absolute value of the spherical aberration at the first cat's eye structure and / or the second cat's eye structure is less than or equal to 2. ,in, satisfy: 。 8. The laser according to any one of claims 4 to 6, characterized in that, The absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to ,in, satisfy: 。 9. A method for generating laser light, characterized in that, Acquire pump light; The first cat's eye structure obtains a first optical signal based on the pump light. The first cat's eye structure is the last cat's eye structure in front of the gain medium of the laser. The first cat's eye structure includes a first lens and a first partial reflector. The gain medium uses the first optical signal to obtain the second optical signal, and the gain medium is placed at the exit pupil position of the first cat's eye structure. The second cat's-eye structure generates a third optical signal based on the second optical signal. This second cat's-eye structure is the last cat's-eye structure of the laser, and it includes a second lens and a second reflector. The cat-eye constant of the second cat-eye structure The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... Satisfaction: In the middle, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first part of the reflector and the first lens. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

10. The method according to claim 9, characterized in that, The absolute value of the spherical aberration at the first cat's eye structure and / or the second cat's eye structure is less than or equal to 2. ,in, satisfy: 。 11. The method according to claim 9 or 10, characterized in that, The absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to ,in, satisfy: 。 12. A method for generating laser light, characterized in that, Acquire pump light; The third cat's-eye structure obtains the first optical signal based on the pump light. The third cat's-eye structure is the last cat's-eye structure before the gain medium. The third cat's-eye structure includes a third lens and a third dichroic mirror. The gain medium uses the first optical signal to obtain the second optical signal; The fourth cat's-eye structure processes the second optical signal to obtain the third optical signal. The fourth cat's-eye structure is the first cat's-eye structure after the gain medium. The fourth cat's-eye structure includes a fourth lens and a first part of a reflector. The first cat's-eye structure generates a fourth light signal based on the third light signal. The first cat's-eye structure is located between the fourth cat's-eye structure and the second cat's-eye structure. The first cat's-eye structure includes a first lens and a first partial reflector. The second cat's-eye structure generates the fifth optical signal based on the fourth optical signal. This second cat's-eye structure is the last cat's-eye structure of the laser, and it includes a second lens and a second reflector. The cat-eye constant of the second cat-eye structure The absolute value of is the distance between the second lens and the second partial reflector, and the cat's eye constant is... satisfy: In the formula, the intermediate quantity A satisfies: The intermediate quantity B satisfies: The intermediate quantity C satisfies: The intermediate quantity D satisfies: intermediate quantity ,in, The absolute value of is the working distance of the laser. The absolute value is the distance between the first lens and the first partial reflector. Let be the focal length of the first lens. Let be the focal length of the second lens. The focal length of the thermal lens of the gain medium. The wavelength of the laser. The radius of the laser spot at the first part of the reflector.

13. The method according to claim 12, characterized in that, The cat-eye constant of the fourth cat-eye structure satisfy: In the formula, intermediate quantities satisfy: intermediate quantity satisfy: ,in, The absolute value is the distance from the third lens to the gain medium. The focal length of the third lens is... The absolute value of is the cat's eye constant. The deviation from the ideal value, where the ideal value is... , The absolute value is the distance from the third lens to the third dichroic mirror. The absolute value of is the distance from the gain medium to the fourth lens. The focal length of the fourth lens is given.

14. The method according to claim 13, characterized in that, The The following relationship must be satisfied: In the formula, intermediate quantities satisfy: intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: intermediate quantity satisfy intermediate quantity satisfy: .

15. The method according to any one of claims 12 to 14, characterized in that, The absolute value of the spherical aberration at the first cat's eye structure and / or the second cat's eye structure is less than or equal to 2. ,in, satisfy: 。 16. The method according to any one of claims 12 to 14, characterized in that, The absolute value of the field curvature at the first cat's-eye structure and / or the second cat's-eye structure is less than or equal to ,in, satisfy: 。 17. A charging system, characterized in that, include: Laser, the laser comprising any one of claims 1 to 8; A control circuit for controlling the electrical switches in the charging system; A driving circuit is used to provide a pump source for the laser.

18. The charging system according to claim 17, characterized in that, The system also includes: A photovoltaic cell is used to receive the laser light generated by the laser and convert the light energy of the laser light into electrical energy.

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