阅读说明：本技术 固体激光器 (Solid laser ) 是由 杨天书 周宗权 唐中阳 李传锋 郭光灿 于 2019-09-05 设计创作，主要内容包括：本公开提供了一种固体激光器,该固体激光器包括：种子光源,用于发射红外种子光；光纤放大器,经由输入光纤与种子光源连接,用于放大种子光；第一倍频晶体,用于将放大后的种子光倍频得到倍频光,其中,倍频光为可见光。(The present disclosure provides a solid state laser, including: a seed light source for emitting infrared seed light; an optical fiber amplifier connected to the seed light source via an input optical fiber for amplifying the seed light; and the first frequency doubling crystal is used for doubling the frequency of the amplified seed light to obtain frequency doubling light, wherein the frequency doubling light is visible light.)

1. A solid state laser, comprising:

a seed light source for emitting infrared seed light;

the optical fiber amplifier is connected with the seed light source through an input optical fiber and is used for amplifying the infrared seed light; and

a first frequency doubling crystal for doubling the frequency of the amplified infrared seed light to obtain frequency doubled light,

wherein the frequency doubling light is visible light.

2. The solid state laser of claim 1, further comprising:

a first beam splitter, disposed in a propagation direction of the frequency doubled light, for dividing the frequency doubled light into at least two beams of light, wherein a first beam of light of the at least two beams of light is used as feedback light, and at least one beam of light of the at least two beams of light except the first beam of light is used as output light of the solid-state laser; and

and the frequency locking feedback component is arranged in the propagation direction of the feedback light and used for determining the line width of the feedback light and feeding back an error signal to the seed light source according to the line width so as to adjust the frequency of the infrared seed light emitted by the seed light source.

3. The solid state laser of claim 2, wherein the frequency-locked feedback component comprises:

a fabry-perot cavity;

the second beam splitter is arranged in the propagation direction of the feedback light, is used for transmitting the feedback light and reflecting the reflected light of the feedback light reflected by the Fabry-Perot cavity;

a detector provided in a propagation direction of the reflected light reflected by the second beam splitter, for detecting the reflected light; and

and the feedback device is used for determining the line width of the feedback light according to the detection result of the detector and feeding back the error signal to the seed light source according to the line width of the feedback light.

4. The solid state laser of claim 3, wherein:

the Fabry-Perot cavity is a flat concave cavity; and/or

The Fabry-Perot cavity is arranged in a constant temperature component, wherein the constant temperature component is provided with a group of light-transmitting windows which are oppositely arranged so as to enable the feedback light to be emitted into or out of the Fabry-Perot cavity.

5. The solid state laser of claim 2, wherein:

the solid state laser further includes: and the band-pass filter is arranged at the position of the front end of the first beam splitter in the propagation direction of the frequency doubling light and used for filtering the residual seed light passing through the first frequency doubling crystal.

6. The solid state laser of claim 2, further comprising:

and the noise filtering component is arranged in the propagation direction of the output light and is used for filtering the output light.

7. The solid state laser of claim 1, further comprising:

a first optical isolator disposed between the optical fiber amplifier and the first frequency doubling crystal in a propagation direction of the amplified seed light, for preventing the amplified seed light from being reflected to the optical fiber amplifier; and/or

And the second optical isolator is arranged at the position of the rear end of the first frequency doubling crystal in the propagation direction of the frequency doubling light and used for preventing the frequency doubling light from being reflected to the first frequency doubling crystal.

8. The solid state laser of claim 1, further comprising:

and the at least one dichroic mirror is arranged in the propagation direction of the frequency doubling light, and is used for transmitting or reflecting the frequency doubling light and reflecting or transmitting the residual seed light passing through the first frequency doubling crystal.

9. The solid state laser of claim 1, wherein:

the first frequency doubling crystal is arranged in the temperature controllable component so that the temperature of the first frequency doubling crystal meets the phase matching condition,

wherein the temperature controllable component has a light-passing hole for the seed light to enter the first frequency doubling crystal.

10. The solid state laser of claim 1, wherein:

the input optical fiber is a polarization maintaining optical fiber; and/or

The output optical fiber of the optical fiber amplifier is a single mode optical fiber; and/or

The optical fiber in the optical fiber amplifier is a rare earth doped optical fiber, and the rare earth element doped by the rare earth doped optical fiber is matched with the wavelength of the seed light emitted by the seed light source.

Technical Field

The present disclosure relates to the field of laser technology, and more particularly, to a solid state laser.

Background

Because the laser has the advantages of high brightness, good collimation, good monochromaticity, strong coherence and the like, the laser is widely applied to various fields of physics, chemistry, biology, medicine, engineering and the like. Some typical uses include: the medical field is used for bloodless surgery, laser treatment, etc., the industrial field is used for welding, cutting, etc., and the physical field is used for laser spectroscopy, laser cooling, etc.

In the course of implementing the disclosed concept, the inventors found that there are at least the following problems in the prior art: the high-power narrow-linewidth visible light laser which is commercially used internationally at present comprises a dye laser and a tapered amplified frequency-doubled laser. Among them, in the dye laser, since the dye is easily bleached and needs to be replaced frequently, and the bleaching is faster as the power is higher, frequent maintenance is required, and the power is limited to about 2W, and it is difficult to obtain higher power. For a conical amplification frequency-doubled solid laser, the amplification mode adopted at present is a conical amplifier (TA), and for all infrared bands, the amplification power of the TA can only reach 3.5W at most, so that the power of most TA amplification frequency-doubled visible light lasers is limited to about 2W. The power of about 2W is far from meeting the requirements of many scientific experiments or industrial applications.

Disclosure of Invention

In view of the above, the present disclosure provides a solid state laser capable of increasing power, reducing line width, and stabilizing power.

The present disclosure provides a solid state laser, comprising: a seed light source for emitting infrared seed light; the optical fiber amplifier is connected with the seed light source through an input optical fiber and is used for amplifying the infrared seed light; and the first frequency doubling crystal is used for doubling the frequency of the amplified infrared seed light to obtain frequency doubling light, wherein the frequency doubling light is visible light.

Optionally, the solid-state laser further includes: the first beam splitter is arranged in the propagation direction of the frequency doubling light and is used for dividing the frequency doubling light into at least two beams of light, wherein a first beam of light in the at least two beams of light is used as feedback light, and at least one beam of light except the first beam of light in the at least two beams of light is used as output light of the solid laser; and the frequency locking feedback assembly is arranged in the propagation direction of the feedback light and used for determining the line width of the feedback light and feeding back an error signal to the seed light source according to the line width so as to adjust the frequency of the infrared seed light emitted by the seed light source.

Optionally, the frequency-locking feedback component includes: a fabry-perot cavity; the second beam splitter is arranged in the propagation direction of the feedback light, and is used for transmitting the feedback light and reflecting the reflected light of the feedback light reflected by the Fabry-Perot cavity; a detector disposed in a propagation direction of the reflected light reflected by the second beam splitter, for detecting the reflected light; and the feedback device is used for determining the line width of the feedback light according to the detection result of the detector and feeding back an error signal to the seed light source according to the line width of the feedback light.

Optionally, the fabry-perot cavity is a flat cavity; and/or the Fabry-Perot cavity is arranged in the constant temperature component, wherein the constant temperature component is provided with a group of light-transmitting windows which are oppositely arranged so as to enable the feedback light to be emitted into or out of the Fabry-Perot cavity.

Optionally, the solid-state laser further includes: and the band-pass filter is arranged at the front end of the first beam splitter in the propagation direction of the frequency doubling light and used for filtering the residual seed light passing through the first frequency doubling crystal.

Optionally, the solid-state laser further includes a noise filtering component disposed in a propagation direction of the output light, for filtering the output light.

Optionally, the solid-state laser further includes a first optical isolator disposed at a position between the optical fiber amplifier and the first frequency doubling crystal in the propagation direction of the amplified seed light, for preventing the amplified seed light from being reflected to the optical fiber amplifier; and/or, the solid laser further comprises a second optical isolator, which is arranged at the rear end of the first frequency doubling crystal in the propagation direction of the frequency doubling light and is used for preventing the frequency doubling light from being reflected to the first frequency doubling crystal.

Optionally, the solid-state laser further includes: and the at least one dichroic mirror is arranged in the propagation direction of the frequency doubling light and is used for transmitting or reflecting the frequency doubling light and reflecting or transmitting the residual seed light passing through the first frequency doubling crystal.

Optionally, the solid-state laser further includes: the light absorption plate is arranged at the rear end of the at least one bicolor mirror in the propagation direction of the residual seed light and is used for absorbing the residual seed light; alternatively, the solid-state laser may further include: and the second frequency doubling crystal is arranged at the rear end of the at least one bichromatic mirror in the propagation direction of the residual seed light and is used for doubling the frequency of the residual seed light to obtain frequency doubled light.

Optionally, the first frequency doubling crystal is disposed in the temperature controllable assembly, so that the temperature of the first frequency doubling crystal satisfies the phase matching condition, wherein the temperature controllable assembly has a light-passing hole for allowing the seed light to enter the first frequency doubling crystal.

Optionally, the input optical fiber is a polarization maintaining optical fiber; and/or the output fiber of the fiber amplifier is a single mode fiber; and/or the optical fiber in the optical fiber amplifier is a rare earth doped optical fiber, and the rare earth element doped by the rare earth doped optical fiber is matched with the wavelength of the seed light emitted by the seed light source.

According to the embodiment of the disclosure, since the optical fiber amplifier is used for amplifying the seed light, compared with the technical scheme of amplifying the seed light by using the cone-shaped amplifier in the prior art, the amplification factor of the seed light can be effectively improved, and the output of high-power visible light can be realized after the frequency multiplication by the frequency multiplication crystal. Moreover, because the frequency-doubled light after frequency doubling of the frequency-doubled crystal can be split and then respectively passes through the frequency-locking feedback component and the noise filtering component, the frequency and the power stability of the output light of the solid laser can be improved, and the requirements of scientific experiments and industrial application are met.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

fig. 1 schematically shows a structural schematic of a solid state laser according to a first embodiment of the present disclosure;

fig. 2A schematically shows a block diagram of a solid-state laser according to a second embodiment of the present disclosure;

fig. 2B schematically shows a specific structural diagram of the solid-state laser described with reference to fig. 2A;

fig. 3 schematically shows a structural schematic of a solid state laser according to a third embodiment of the present disclosure;

fig. 4 schematically shows a structural schematic of a solid state laser according to a fourth embodiment of the present disclosure;

figure 5A schematically shows a measurement of the frequency bandwidth with reference to the fabry-perot cavity in figure 4;

FIG. 5B schematically shows a partial result enlargement referring to the measurement result of the frequency bandwidth in FIG. 5A; and

fig. 6 schematically shows a beat frequency measurement result diagram of visible light output from the solid state laser and output light from the commercial laser according to the fourth embodiment of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.

Fig. 1 schematically shows a structural schematic diagram of a solid-state laser according to a first embodiment of the present disclosure.

As shown in fig. 1, a solid-state laser 100 according to an embodiment of the present disclosure includes a seed light source 101, a fiber amplifier 102, and a first frequency doubling crystal 103.

Wherein the seed light source 101 is used for emitting infrared seed light. The seed light source 101 may specifically include, for example, a controller and a laser source, wherein the controller is configured to control parameters such as power and frequency of the infrared seed light emitted by the laser source.

According to the embodiment of the present disclosure, the laser source may be, for example, a tunable laser, and specifically, may be, for example, a semiconductor laser continuously tuned to 10-20GHz without mode hopping. Which is tunable with a wavelength of, for example, ± 17.5nm, the emitted infrared seed light may, for example, be seed light having a wavelength of, for example, 1212 nm. The output power of the seed light source 101 may be, for example, about 100 mW. It is to be understood that the type of laser source and the parameters described above are merely examples to facilitate understanding of the present disclosure, and the present disclosure is not limited thereto. Among them, the type and parameters of the seed light source 101 may be determined by the wavelength of the desired frequency doubled light.

According to an embodiment of the present disclosure, in order to ensure the stability of the seed light emitted by the seed light source 101, the seed light source 101 may be placed on a vibration-damping table, for example, to isolate the influence of external vibration on the stability of the seed light emitted by the seed light source 101.

The optical fiber amplifier 102 may be connected to the seed light source 101 through an input optical fiber 104, for example, to collect seed light emitted from the seed light source 101. When the output power of the seed light source 101 is 100mW, the power of the seed light collected through the input optical fiber is about 65 mW. The input fiber may be, for example, a Polarization maintaining optical fiber (Polarization maintaining optical fiber) to maintain a specific Polarization of the infrared seed light required by the transmitting amplifier. It will be appreciated that the input fiber may be, for example, a conventional fiber, and that in order to maintain a particular polarization of the seed light, a polarizer may be placed between the conventional fiber and the fiber amplifier 102, for example, while the fiber needs to be fixed.

The fiber amplifier 102 may amplify the seed light using stimulated raman scattering, for example, in accordance with embodiments of the present disclosure. Accordingly, the fiber amplifier 102 includes an active pump source and a raman fiber amplifier. The pump source is used to provide a pump source for the raman fiber amplifier, wherein the fiber in the raman fiber amplifier may be, for example, a rare earth doped fiber. The type of the rare-earth-doped optical fiber (the type of the rare-earth-doped optical fiber) may be specifically determined according to the wavelength of the seed light, for example, that the rare-earth-doped optical fiber is doped with the rare-earth element and the wavelength of the seed light emitted by the seed light source 101 are matched, so as to amplify the seed light. For example, in the case where the seed light has a wavelength of 1212nm, an optical fiber doped with an ytterbium (Yb) element may be used. According to the embodiment of the disclosure, under the condition that the power of the infrared seed light emitted by the seed light source 101 and input to the amplifier is 40mW, the power of the amplified infrared seed light obtained after amplification by the optical fiber amplifier can be up to 30.5W, for example, compared with the technical scheme that the power of the amplified infrared seed light can only reach 3.5W by adopting a tapered amplifier in the prior art, the amplification factor can be effectively improved, thereby being beneficial to improving the output power of the frequency doubled light obtained by subsequent frequency doubling.

According to the embodiment of the present disclosure, in order to ensure the spot quality of the seed light amplified by the optical fiber amplifier, the output optical fiber of the optical fiber amplifier may adopt a single mode optical fiber, for example.

The first frequency doubling crystal 103 is configured to double the frequency of the amplified seed light to obtain a frequency doubled light. The first frequency doubling crystal 103 may be a nonlinear crystal, for example. For the solid state laser structure referred to in fig. 1, the first frequency doubling crystal 103 may be a periodically poled crystal, and may include, for example, a Periodically Poled Lithium Niobate (PPLN) crystal, a periodically poled potassium titanyl phosphate (PPKTP) crystal, or a Periodically Poled Stoichiometric Lithium Tantalate (PPSLT) crystal. .

According to the embodiment of the present disclosure, in order to facilitate the output of the doubled light obtained by frequency doubling through the first frequency doubling crystal 103, a fiber collimator may be disposed at the rear end of the first frequency doubling crystal 103, for example, to collect the doubled light for output, so as to facilitate use.

According to the embodiment of the disclosure, in order to improve the frequency doubling efficiency of the frequency doubling crystal, the temperature of the first frequency doubling crystal 103 should satisfy the phase matching condition. In order to make the temperature satisfy the phase matching condition, the first frequency doubling crystal 103 is, for example, disposed in a temperature controllable component to control the temperature of the first frequency doubling crystal 103, so that the temperature of the first frequency doubling crystal 103 can make the crystal achieve quasi-phase matching required by the nonlinear effect, thereby achieving phase matching.

According to an embodiment of the present disclosure, the temperature controllable component is specifically provided with a light passing hole for enabling seed light to enter the first frequency doubling crystal. The temperature-controllable component may be, for example, a temperature-controlled furnace, and the temperature of the temperature-controlled furnace may be controlled by, for example, a temperature controller, wherein the precision of the selected temperature controller may be, for example, ± 0.01K.

According to the embodiment of the present disclosure, the first frequency doubling crystal 103 may specifically be, for example, a PPSLT crystal, and when the frequency doubling efficiency of the PPSLT crystal is at least 14.6%, for example, the power of the amplified infrared seed light is 30.5W, and the power of the frequency doubled light obtained by frequency doubling through the first frequency doubling crystal 103 is at least 4.4W.

In summary, the solid-state laser according to the embodiment of the disclosure can obtain output power of several watts to several tens of watts by adopting the technical scheme that the infrared seed light is amplified by the optical fiber amplifier and then frequency-doubled by the frequency doubling crystal, so as to obtain high-power visible light laser.

Fig. 2A schematically shows a block diagram of a solid-state laser according to a second embodiment of the present disclosure; fig. 2B schematically shows a specific structural diagram of the solid-state laser described with reference to fig. 2A.

As shown in fig. 2A to 2B, the solid-state laser 200 according to the embodiment of the disclosure may further include, for example, a first beam splitter 204 and a frequency-locking feedback component 205, in addition to the seed light source 201, the fiber amplifier 202 and the first frequency doubling crystal 203.

The first beam splitter 204 is disposed in a propagation direction of the frequency doubled light obtained by frequency doubling by the first frequency doubling crystal 203, and is configured to divide the frequency doubled light into at least two beams. As shown in fig. 2A-2B, the first light beam is emitted as feedback light into the frequency-locked feedback module, and at least one light beam except the first light beam is used as the output light of the solid-state laser 200.

According to an embodiment of the present disclosure, the first beam splitter 204 may be, for example, a polarization beam splitter, and a specific type of the beam splitter may be determined according to a wavelength of the frequency doubled light obtained by frequency doubling, so as to split the frequency doubled light into two beams of light after reflection and transmission.

As shown in fig. 2A, the frequency-locked feedback component 205 is disposed in a propagation direction of the feedback light, and configured to feed back an error signal to the seed light source 201 according to a line width of the feedback light, so as to adjust a frequency of the seed light emitted by the seed light source 201.

As shown in fig. 2A to 2B, the solid-state laser 200 according to the embodiment of the present disclosure may further include a noise filtering component 206. The noise filter 206 is disposed in the propagation direction of the output light, and is used to filter the intensity noise and the frequency noise of the output light caused by the fiber amplifier 202, so that the frequency and the power of the output light are more stable.

According to an embodiment of the present disclosure, the noise filter assembly 206 may be, for example, an annular fabry-perot cavity (annular FP cavity). As shown in fig. 2B, the annular FP cavity may be composed of, for example, two concave mirrors and a flat mirror.

As shown in fig. 2B, the frequency-locked feedback component 205 may specifically include a fabry-perot cavity (FP cavity) 2051, a second beam splitter 2052, a detector 2053, and a feedback 2054.

Wherein the FP cavity 2051 can be used as an optical reference cavity because only light having a wavelength equal to an integer multiple of the cavity length of the FP cavity 2051 will be transmitted out of the FP cavity 2051, while light having a wavelength not equal to an integer multiple of the cavity length of the FP cavity 2051 will be reflected out of the FP cavity. Therefore, the light transmitted through the FP cavity 2051 is light of a fixed wavelength (i.e., a fixed frequency), and thus the FP cavity 2051 can be used as a reference for determining whether the frequency of the feedback light is a stable frequency.

According to the embodiment of the disclosure, it is considered that when the FP cavity adopts a flat cavity, it is often necessary to ensure accurate parallelism of two plane mirrors forming the FP cavity, so as to ensure stability of the FP cavity as a reference cavity. In order to make the FP cavity more stable, as shown in fig. 2B, the FP cavity may be a plano-concave FP cavity, that is, the FP cavity 2051 is composed of a plane mirror and a concave mirror. One end of the plane mirror is used as an input end, and one end of the concave mirror is used as an output end. Therefore, when the frequency of the feedback light resonates with the FP cavity, the feedback light can be transmitted out of the FP cavity 2051 from the concave mirror.

According to the embodiment of the disclosure, in order to further improve the stability of the FP cavity 2051 and avoid the influence of the external temperature change on the cavity length or other parameters of the FP cavity 2051, the FP cavity 2051 may be placed in a constant temperature component, specifically, for example, may be disposed in a temperature controller, which ensures that the FP cavity 2051 is in a constant temperature environment. Wherein the thermostatic assembly is provided with a set of light-transmitting windows arranged oppositely for transmitting feedback light into or out of the FP cavity 2051.

According to an embodiment of the present disclosure, the above-mentioned flat-concave FP cavity 2051 may specifically include two high-reflectivity cavity mirrors (one is a plane mirror and one is a concave mirror), the fineness (ratio of mode spacing to spectral width) of which is 10000, and the free spectral range of which is 1.5 GHz. For scaling the bandwidth of the feedback light that finally outputs the plano-concave FP cavity.

The second beam splitter 2052 is disposed at a position at the front end of the FP cavity in the propagation direction of the feedback light, and is configured to transmit the feedback light divided by the first beam splitter 204, so that the feedback light is incident into the FP cavity. Meanwhile, in order to facilitate the detector 2053 to detect the reflected light of the feedback light, which is not transmitted but reflected by the FP cavity, the second beam splitter 2052 may reflect the reflected light via the fabry-perot cavity again, for example, to change the propagation direction of the reflected light (specifically, for example, to change by 90 °).

Accordingly, the detector 2053 is provided in the propagation direction of the reflected light reflected by the second beam splitter 2052, and detects the reflected light. According to an embodiment of the present disclosure, the probe 2053 may be electrically connected to the feedback 2054, for example, to feed back the detection result to the feedback 2054.

The feedback unit 2054 is configured to determine a line width of the reflected light (i.e., the reflected feedback light) according to a detection result of the detector, and feed back an error signal to the seed light source according to the line width of the feedback light. The line width may be directly measured according to the detection result, and the line width includes line width noise that may be caused by all links in the whole solid-state laser system.

Specifically, considering that the light passing through the FP cavity 2051 is equal to the resonance frequency of the FP cavity 2051, an error signal between the frequency of the feedback light (i.e., the seed light emitted by the seed light source 201) and the resonance frequency can be determined by the feedback device 2054 through a series of calculations according to the line width and the frequency of the reflected feedback light and the resonance frequency of the FP cavity 2051, and then the error signal can be used to drive adjustment of parameters of the seed light source 201, so that the frequency of the output light of the solid-state laser is finally locked on the resonance frequency which is in resonance with the FP cavity 2051.

According to an embodiment of the present disclosure, referring to fig. 2B, the frequency-locked feedback system 205 may specifically, for example, implement high-speed feedback operation control by using a PDH (Pound-Drever-Hall) -based frequency locking method to implement adjustment of the frequency of the seed light emitted by the seed light source 201. The FP cavity in the above embodiments is used as a stable frequency standard only as an example to facilitate understanding of the present disclosure, and the present disclosure does not limit this. For example, the feedback mode adopted by the embodiment of the present disclosure may further include a stable frequency standard such as an atomic line absorption line, for example.

According to an embodiment of the present disclosure, the error signal mentioned above may specifically be fed back to a controller in the seed light source 201, for example, to control the frequency of the seed light emitted by the laser source via the controller. In the embodiment of the present disclosure, the error signal may be fed back to the seed light source 201 through a high-speed channel and/or a low-speed channel, for example. Wherein the error signal can be fed back to the controller of the seed light source 201 through high-speed channel feedback and the excitation current provided by the controller is changed. The error signal may be fed back to the controller of the seed light source 201 through low speed channel feedback and the piezo ceramic voltage in the controller may be varied to vary the cavity length of the laser source or to vary the temperature at which the laser source is controlled.

According to the embodiment of the disclosure, considering that only feedback light with the same frequency as the resonance frequency of the FP cavity 2051 will pass through the FP cavity 2051, as shown in fig. 2B, the frequency-locked feedback component 205 may further be provided with another detector 2055 on the output side of the FP cavity 2051, for detecting the feedback light passing through the FP cavity 2051 and feeding back the detection result to the feedback 2054. The feedback device 2054 can obtain the frequency locking state and the line width of the current feedback light according to the detection result, and thus obtain the resonant frequency of the FP cavity 2051. Thereby facilitating the feedback 2054 to determine and transmit an error signal based on the resonant frequency.

In summary, the first beam splitter and the frequency-locking feedback assembly are arranged, so that the frequency of the seed light emitted by the seed light source can be effectively controlled, and a good frequency-locking effect is achieved. Specifically, the solid-state laser according to the embodiment of the present disclosure, through the arrangement of the frequency-locking feedback component, the line width of the finally output visible light can be narrowed to the KHz level or below, so that the frequency and the power of the visible light output by the solid-state laser according to the embodiment of the present disclosure have good stability.

According to the embodiment of the present disclosure, the frequency and power of the output light of the solid-state laser can be more stable by the arrangement of the frequency-locking feedback component 205 and the noise filtering component 206. The frequency-locked feedback component 205 is equivalent to actively reducing the noise of the infrared seed light, and the noise filtering component 206 is equivalent to passively filtering the noise generated by the fiber amplifier 202.

Fig. 3 schematically shows a structural schematic diagram of a solid-state laser according to a third embodiment of the present disclosure.

As shown in fig. 3, a solid-state laser 300 according to an embodiment of the present disclosure includes a seed light source 301, a fiber amplifier 302, a first frequency doubling crystal 303, a first beam splitter 304, a frequency-locked feedback component 305, and a noise filtering component 306. The frequency-locked feedback component 305 is composed of an FP cavity 3051, a second beam splitter 3052, a detector 3053, a feedback 3054 and another detector 3055. The above device structure is the same as or similar to the structure of the solid-state laser 300 described with reference to fig. 2A-2B, and is not repeated here.

According to an embodiment of the present disclosure, as shown in fig. 3, the solid state laser 300 may further include a first optical isolator 307. The first optical isolator 307 is disposed between the optical fiber amplifier 302 and the first frequency doubling crystal 303 in the propagation direction of the amplified seed light, and is used for preventing the amplified seed light from reflecting and then entering the optical fiber amplifier 302 again. Thereby avoiding damage to the fiber amplifier 302 from light reflected to the fiber amplifier 302. The specific type and parameters of the first optical isolator 307 can be selected according to the wavelength of the seed light, so as to achieve effective isolation of the seed light.

According to the embodiment of the present disclosure, as shown in fig. 3, the solid-state laser 300 may further include, for example, a second optical isolator 308, where the second optical isolator 308 is disposed at a position behind the first frequency doubling crystal 303 in the propagation direction of the frequency doubled light, and is used to prevent the frequency doubled light from being reflected to the first frequency doubling crystal 303, and even to the fiber amplifier 302. And thus to avoid damage to the first frequency doubling crystal 303 and the fiber amplifier 302 by the reflected light. The specific type and parameters of the second optical isolator 308 can be selected according to the wavelength of the frequency doubled light, so as to achieve effective isolation of the frequency doubled light.

According to the embodiment of the present disclosure, it is considered that the doubling efficiency of the first doubling crystal 303 is generally about 14%. The seed light amplified by the fiber amplifier 302 will have an influence on the purity of the finally output visible light after a part of un-frequency-doubled residual seed light is emitted when the seed light is frequency-doubled by the first frequency doubling crystal 303. To prevent such an influence, as shown in fig. 3, the solid-state laser 300 of the embodiment of the present disclosure may further include a band-pass filter 309. The band-pass filter 309 is disposed at a front end of the first beam splitter 304 in the propagation direction of the doubled light, and is configured to filter the residual seed light passing through the first frequency doubling crystal, and only allow light with the same wavelength as the doubled light to pass through and enter the first beam splitter 304. Therefore, the band-pass filter 309 can improve the purity of the finally outputted visible light to some extent.

According to the embodiment of the present disclosure, in order to effectively split the residual seed light passing through the first frequency doubling crystal 303 and the frequency doubling light, it is convenient to realize recycling of the residual seed light. As shown in fig. 3, the solid-state laser 300 may further include, for example, a dichroic mirror 310, and the dichroic mirror 310 may be, for example, one, and is disposed in a propagation direction of the frequency-doubled light emitted through the first frequency-doubling crystal 303, so as to transmit the frequency-doubled light with frequency doubled by the first frequency-doubling crystal 303 and reflect the residual seed light without frequency doubling by the first frequency-doubling crystal 303.

Accordingly, as shown in fig. 3, the solid-state laser 300 further includes a second frequency doubling crystal 311 in addition to the dichroic mirror 310, and the second frequency doubling crystal 311 is disposed at a position at the rear end of the dichroic mirror 310 in the propagation direction of the residual seed light reflected by the dichroic mirror 310, so as to double the frequency of the residual seed light again to obtain a frequency doubled light, and the frequency doubled light can also be used as the output of the solid-state laser 300. In this case, in order to stabilize the frequency and power of the multiplied light outputted through the second frequency doubling crystal 311, as shown in fig. 3, a noise filtering component 306 may be disposed at the rear end of the second frequency doubling crystal 311 to filter the multiplied light outputted from the second frequency doubling crystal 311, so as to filter out the intensity noise and frequency noise caused by the second frequency doubling crystal 311.

It can be understood that, in order to avoid the existence of the second residual seed light which is not frequency-doubled in the residual seed light frequency-doubled by the second frequency doubling crystal 311, a combined structure of a dichroic mirror and a frequency doubling crystal may be further disposed at the rear end of the second frequency doubling crystal 311, so as to recycle the second residual seed light.

In summary, in the embodiment of the present disclosure, by setting the dichroic mirror and the second frequency doubling crystal, the frequency of the residual seed light can be doubled again, so as to effectively utilize the seed light, and thus, the power of the finally output visible light is further improved.

Fig. 4 schematically shows a structural schematic diagram of a solid-state laser according to a fourth embodiment of the present disclosure.

As shown in fig. 4, the solid laser 400 according to the embodiment of the disclosure includes one dichroic mirror 410, and the dichroic mirror 410 is configured to reflect the frequency doubled light with the frequency doubled by the first frequency doubling crystal 403, and transmit the residual seed light without the frequency doubled by the first frequency doubling crystal 403.

Furthermore, the embodiment of the present disclosure considers that the configuration of the second frequency doubling crystal and the additional dichroic mirror and the frequency doubling crystal may affect the stability of the overall structure of the solid-state laser in order to recycle the residual seed light. Therefore, the embodiment of the present disclosure does not provide the second frequency doubling crystal, but in the propagation direction of the residual seed light, a light absorption plate (Beam Block)411 is disposed at a position at the rear end of the dichroic mirror 410 for absorbing the residual seed light transmitted through the dichroic mirror, so as to prevent the transmitted residual seed light from damaging other articles or causing injury to a user.

It should be noted that the flat concave FP cavity 4051 in this embodiment is, for example, a cavity with a fineness of 10000 and a free spectral range of 1.5 GHz.

Figure 5A schematically shows a measurement of the frequency bandwidth with reference to the plano-concave fabry-perot cavity of figure 4; and fig. 5B schematically shows a partial result enlarged view referring to the measurement result of the frequency bandwidth in fig. 5A.

As shown in fig. 5A-5B are measurements of the frequency bandwidth of the feedback light transmitted through the plano-concave FP cavity 4051 detected by reference to another detector 4055 in fig. 4.

In the measuring process, the measuring result of the transmitted feedback light is accessed into an oscilloscope, and then a measuring result graph of the frequency bandwidth can be obtained. As shown in fig. 5A, the center frequency of the feedback light is the frequency represented by the main peak with a large peak value on the right side, and the sideband on the left side of the right peak is generated by loading a resonance type electro-optical modulator on the optical path of the frequency doubling light of the solid laser shown in fig. 4, the operating frequency of the electro-optical modulator is 15MHz, so that the distance between the main peak and the sideband is 15 MHz. The half-height width of the main peak is 158KHz calculated from the measurement result of the frequency bandwidth in reference to fig. 5B, which matches 150KHz calculated from the parameter fineness 10000 of the FP cavity 4051 and the free spectral range 1.5 GHz. Meanwhile, by measuring the fluctuation of the transmitted light intensity after frequency locking, the line width of the visible light after frequency locking is less than 1.44 KHz.

In summary, the solid-state laser provided by the present disclosure can output visible light with power greater than 3.2W and line width less than 1.44KHz, and has a wider application scenario compared to the visible light solid-state laser in the prior art. And because each device in the solid laser is a universal device, the device has high stability and is easy to assemble.

Fig. 6 schematically shows a beat frequency measurement result diagram of visible light output from the solid state laser and output light from the commercial laser according to the fourth embodiment of the present disclosure.

The solid laser shown in fig. 4 and a commercial laser (a laser with a narrow linewidth and a power of less than 1W) of Toptica corporation were used for testing, and beat frequency measurement was performed on output light of the solid laser and output light of the commercial laser, so as to obtain a measurement result shown in fig. 6. Wherein, beat frequency results of two lasers in the measurement result satisfy the following relation:

wherein Δ_FWHMIs the measured beat line width, Δ₁And Δ₂Respectively corresponding to the line widths of the two lasers. Since the beat frequency line width measured is 2.71KHz, it can be shown that the line width of the solid laser in fig. 4 and the line width of the commercial laser of Toptica corporation are both less than 2.71 KHz. Therefore, the solid-state laser in fig. 4 can ensure the output power much higher than that of the commercial laser of Toptica, while ensuring the same narrow linewidth as that of the commercial laser, compared to the commercial laser of Toptica.

Those skilled in the art will appreciate that various combinations and/or combinations of features recited in the various embodiments and/or claims of the present disclosure can be made, even if such combinations or combinations are not expressly recited in the present disclosure. In particular, various combinations and/or combinations of the features recited in the various embodiments and/or claims of the present disclosure may be made without departing from the spirit or teaching of the present disclosure. All such combinations and/or associations are within the scope of the present disclosure.

While the disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Accordingly, the scope of the present disclosure should not be limited to the above-described embodiments, but should be defined not only by the appended claims, but also by equivalents thereof.