CN102545013B - Laser gain device and method - Google Patents

Abstract

A laser gain device and method, the device includes a gain medium, a pump source, an optical element and a controller, the gain medium is arranged on the optical path of the laser, and receives the pump light emitted by the pump source, the The controller is connected with the pump source, and is used to control the pump source to emit pump light to the gain medium, and the pump light enters the gain medium through the optical element, and the controller is also connected with the optical element, and is used to control the The light intensity distribution of the pump light of the optical element. In the method, the light intensity distribution of the pumping light is controlled by a controller, so as to control the gain distribution in the gain medium. The present invention controls the light intensity distribution of the pump light passing through the optical element through a controller, thereby changing the gain distribution in the gain medium to realize spatial modulation of the light intensity of the laser beam, solving the problem of laser loss and damage, and making the laser The beam can be uniform or Gaussian.

Description

A laser gain device and method

technical field

The invention belongs to the technical field of laser light intensity control, and in particular relates to a laser gain device and method.

Background technique

Due to its high brightness, good monochromaticity, good collimation and focusing performance, laser has been widely used in scientific research, military defense, industrial processing, astronomical observation and information dissemination and other fields. In practical applications, people hope to obtain a laser beam with uniform light intensity distribution or close to Gaussian light intensity distribution. For example, in the field of laser etching processing, it is necessary to obtain a flat top beam with light intensity distribution as uniform as possible to achieve the best etching effect; and in the case of laser focusing (such as laser welding, laser drilling, laser fiber coupling ), it is hoped that the light intensity distribution will be as close as possible to the Gaussian beam, so as to increase the light intensity after laser focusing and reduce the spot size of the laser at the focal point.

The existing light intensity distribution control technologies are all transmission attenuation type, and will be limited by factors such as laser light intensity and aperture in practical application. The Chinese patent application with the application number 02820338.0 discloses a thin film semiconductor device and its manufacturing method. It directly uses a mask with a certain light intensity distribution to change the intensity distribution of the light beam and uses it for photolithography of semiconductor devices. The method requires After the intensity distribution of the laser is detected, a mask corresponding to the transmittance distribution is designed and processed, so as to realize the control of the laser intensity distribution. The method affects the real-time performance of the control of the spot distribution of the laser; on the other hand, the method actually attenuates the light intensity, which will cause the power of the laser to be lost; in addition, the damage threshold of this transmissive mask is compared with Low, which also limits its application to high-power lasers. The Chinese patent No. 01256697.7 discloses a liquid crystal light valve laser beam space shaping device, and mentions that the liquid crystal light valve is used to control the light intensity distribution of the laser, but this method can only realize the laser light intensity distribution through attenuation. The control of the laser cannot solve the problem of laser loss and damage.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the present invention is that the prior art can obtain a laser beam with uniform light intensity distribution or close to Gaussian light intensity distribution only through attenuation, which cannot solve the problem of laser loss and damage.

(2) Technical solution

In order to solve the above technical problems, the present invention provides a laser gain device.

Wherein, the device includes a gain medium, a pump source, an optical element and a controller, the gain medium is arranged on the optical path of the laser, and receives the pump light emitted by the pump source, and the controller and the pump source Connected, used to control the pump source to send pump light to the gain medium, the pump light enters the gain medium through the optical element, and the controller is also connected to the optical element, used to control the pump light passing through the optical element light intensity distribution.

Preferably, the optical element includes a liquid crystal light valve, a lens group and a reflector, and a liquid crystal light valve, a lens group and a reflector are sequentially arranged between the pump source and the gain medium, and the controller is connected to the liquid crystal light valve .

Preferably, the optical element includes a deformable mirror and a Fourier transform mirror, the deformable mirror and the Fourier transform mirror are sequentially arranged between the pump source and the gain medium, and the controller is connected to the deformable mirror.

Preferably, the gain medium is Nd:YVO4.

The present invention also provides a laser gain method, in which a gain medium that receives pumping light is provided on the optical path of the laser, and the pumping light enters the gain medium through an optical element connected to a controller, and the controller controls The light intensity distribution of the pump light passing through the optical element makes the light intensity distribution of the pump light before it enters the gain medium within the tolerance range of the preset value, so as to control the gain distribution in the gain medium, so as to realize the light intensity of the laser The strong distribution is modulated as a uniform distribution or a Gaussian distribution.

Preferably, the controller controls the light intensity of the pump light before it is incident on the gain medium to be within the tolerance range of I _pH (x, y),

in, $I_{\mathrm{pH}}(x,\mathrm{the\; y})=C_p\·[\mathrm{In}{A}_0-\mathrm{In}\left(I_i(x,\mathrm{the\; y})\right)+\frac{A_0-I_i(x,\mathrm{the\; y})}{I_{\mathrm{the\; s}}}],$

A₀为激光的光强振幅，I_i(x，y)为激光在增益介质入射面的光强分布，

λ_l为激光波长，λ_p为泵浦光的波长，h为普朗克常量，c为光速，σ₂₁为增益介质的受激发射截面，τ_f为激活离子的上能级寿命，α为增益介质对泵浦光的吸收系数，L为增益介质的长度，x、y为空间坐标，e为欧拉系数。In the formula,

A ₀ is the light intensity amplitude of the laser, I _i (x, y) is the light intensity distribution of the laser on the incident surface of the gain medium,

λ _l is the laser wavelength, λ _p is the wavelength of the pump light, h is Planck's constant, c is the speed of light, σ ₂₁ is the stimulated emission cross section of the gain medium, τ _f is the upper energy level lifetime of the active ion, and α is The absorption coefficient of the gain medium to the pump light, L is the length of the gain medium, x and y are the space coordinates, and e is the Euler coefficient.

Preferably, the controller controls the light intensity of the pump light before entering the gain medium to be within the tolerance range of I _pG (x, y), wherein,

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; pG</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; In</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">y</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; In</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">y</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span>$

λ_l为激光波长，λ_p为泵浦光的波长，h为普朗克常量，c为光速，σ₂₁为增益介质的受激发射截面，τ_f为激活离子的上能级寿命，α为增益介质对泵浦光的吸收系数，L为增益介质的长度，x、y为空间坐标，ω为高斯光束的束腰参数，e为欧拉系数。In the formula, A ₀ is the light intensity amplitude of the laser, I _i (x, y) is the light intensity distribution of the laser on the incident surface of the gain medium,

λ _l is the laser wavelength, λ _p is the wavelength of the pump light, h is Planck's constant, c is the speed of light, σ ₂₁ is the stimulated emission cross section of the gain medium, τ _f is the upper energy level lifetime of the activated ion, and α is The absorption coefficient of the gain medium to the pump light, L is the length of the gain medium, x and y are the space coordinates, ω is the beam waist parameter of the Gaussian beam, and e is the Euler coefficient.

Preferably, it also includes the step of recording the incident light intensity of the laser, when the pump source is turned off, turn on the laser source, record the light intensity distribution I _i (x, y) at the incident surface of the gain medium at this time, and then calculate The value of the light intensity _IpH or _IpG of the pump light before it is incident on the gain medium, and the light intensity of the pump light passing through the optical element is controlled by the controller so that the light intensity of the pump light before the incident gain medium is at _IPH or IpG within the tolerance range of _PG .

Preferably, the optical element includes a liquid crystal light valve, a lens group and a reflector, and a liquid crystal light valve, a lens group and a reflector are sequentially arranged between the pump source and the exit surface of the gain medium, and the controller and the liquid crystal light valve is connected.

Preferably, the optical element includes a deformable mirror and a Fourier transform mirror, and the deformable mirror and the Fourier transform mirror are sequentially arranged between the pump source and the exit surface of the gain medium, and the controller is connected to the deformable mirror .

(3) Beneficial effects

The above-mentioned technical solution has the following advantages: the present invention controls the light intensity distribution of the pump light passing through the optical element through the controller, thereby gaining the laser light, solving the problem of laser loss and damage, and making the pumping light before entering the gain medium The light intensity is within the tolerance range of the preset value, so as to control the gain distribution in the gain medium, so as to realize the modulation of the laser light intensity distribution to a uniform distribution or Gaussian distribution, because there is no influence on the laser light in the process of changing the laser light intensity distribution Active attenuation, so it is easy to control the light intensity distribution of high-power laser beams.

Description of drawings

Fig. 1 is a schematic structural view of a transmissive laser gain device of the present invention;

Fig. 2 is the structural representation of reflective laser gain device of the present invention;

Fig. 3 is a schematic structural view of an embodiment of a device for generating a uniform light intensity laser beam of the present invention;

Fig. 4 is the structural representation of the embodiment of the device for producing Gaussian light intensity laser beam of the present invention;

Fig. 5 is a schematic structural diagram of an embodiment of the present invention.

Among them, 1: gain medium; 2: pump source; 3: pump light; 4a: liquid crystal light valve; 4b: mirror; 4c: lens group; 4a': deformable mirror; 4c': Fourier transform mirror; 5: incident surface of gain medium; 6: laser beam; 7: incident laser; 8: controller; 9: exit surface of gain medium; 10: electrode wire.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

As shown in Figure 1, it is a schematic structural diagram of a transmissive laser gain device of the present invention, the laser gain device includes a gain medium 1, a pump source 2, an optical element and a controller 8, and the gain medium 1 is arranged on the light of the laser On the road, the laser light and the pumping light emitted by the pumping source 2 are received, and the controller is connected with the pumping source 2 for controlling the pumping source 2 to emit pumping light to the gain medium 1, and can adjust the pumping light 3 The pumping light 3 enters the gain medium 1 through the optical element, and the controller 8 is also connected with the optical element to control the light intensity distribution of the pumping light 3 passing through the optical element. The incident surface of the gain medium 1 in this embodiment is used to receive the laser beam 6 , and the gain medium is used to absorb the pump light emitted by the pump source to make its own active ions transition to an excited state. The laser entering the gain medium 1 can be a continuous laser or a pulsed laser. The laser beam can enter the gain medium once or multiple times to form an incident laser. The way of entering the gain medium can be through or through. After entering the medium, it is reflected and exits the medium. The surface of the gain medium 1 facing the laser beam is the incident surface 5 , and the surface facing the pump source 2 is the outgoing surface. The gain medium 1 can be solid, liquid or gas gain medium. The controller of the present invention can be various suitable control components, such as single-chip microcomputer and driver. The invention uses a controller to control the light intensity of the pump light passing through the optical element, thereby gaining the laser beam, solving the problem of laser loss and damage, and making the laser beam into a preset shape, which can be uniform distribution or Gaussian type distribution.

As shown in Figure 2, it is a schematic structural diagram of a reflective laser gain device of the present invention. The gain medium 1 of this embodiment is reflective, and the incident laser light enters and reflects from the incident surface 5 of the gain medium 1. In this embodiment, Both the entrance and exit planes are located on one side of the laser source. The other side of the gain medium 1 is coated with a dichromatic film, so that the pump light can be transmitted into the gain medium 1, while the laser light is reflected back to the incident surface. In this embodiment, in order to improve the reflectivity of the mirror 4b, a film is coated on the surface of the mirror 4b.

The controller of the present invention can be various suitable control elements, such as a driver, a single-chip microcomputer, and the like. The optical element of the present invention can also be various suitable optical components, as long as the light intensity distribution of the pumping light can be controlled. As shown in Fig. 3, it is the structure schematic diagram that the present invention is used to produce uniform intensity laser beam, and this device comprises gain medium 1, pumping source 2, optical device and controller 8, and described optical device comprises liquid crystal light valve 4a, Lens group 4c and reflector 4b, liquid crystal light valve 4a, lens group 4c and reflector 4b are sequentially arranged between the pump source 2 and the gain medium exit surface 9, the controller 8 is a driver, and the liquid crystal light valve 4a connected. The gain medium 1 of this embodiment is Nd:YVO4 (Nd-doped yttrium vanadate), which is a four-level system, its stimulated absorption effect can be ignored, and there are gain medium incident surface 5 and gain medium exit surface 9; laser beam 6 Entering the gain medium incident surface 5 forms incident laser light 7, and this incident laser light is the laser beam that the wavelength that the laser oscillator emits is 1064nm, and the light intensity distribution of the incident laser beam cross-section arriving at the gain medium surface is I _i (x, y) The pump source 2 is a collimated semiconductor laser, and the wavelength of the output light is 808nm; the liquid crystal light valve 4a can change its transmittance distribution by controlling the bias voltage distribution u (x, y) of its liquid crystal array; The mirror surface of 4b is coated with a film layer with high reflectivity to 808nm pump light and high transmittance to 1064nm laser; lens group 4c is a plurality of lenses, and its function is to expand or shrink the beam of pump light 3, so that it is compatible with The apertures of the incident laser light 7 are matched; the driver is connected to the liquid crystal light valve 4a through the electrode line 10, and is used to apply voltage to the liquid crystal light valve through the electrode line 10 connected to the liquid crystal light valve 4a, so as to control the light passing through the liquid crystal light valve 4a. Light intensity distribution of pump light 3. Driven by the driver, a certain voltage is obtained on the electrode line 10 connected to the liquid crystal light valve array 4a, so that the pumping light 3 emitted by the pumping source 2 passes through the liquid crystal light valve 4a, the lens group 4c and the mirror 4b. Arrives at the output surface 9 of the gain medium, and then passes through the output surface 9 of the gain medium and enters the gain medium 1 at normal incidence to generate a gain distribution g(x, y, z). As a special example, if the gain medium 1 is a flat plate, the gain distribution in the gain medium 1 can be approximately regarded as the exponential attenuation of the pump light intensity distribution due to collimation. As shown in Figure 4, it is a schematic structural view of the present invention for producing a laser beam with uniform light intensity. The light intensity distribution of the pump light 3 is used to form a Gaussian beam as shown in FIG. 4 .

As shown in Figure 5, it is a schematic structural diagram of another embodiment of the present invention. The difference from the embodiments in Figures 3 and 4 is that the optical elements of this embodiment include a deformable mirror 4a' and a Fourier transform mirror 4c' and reflector 4b, a deformable mirror 4a' and a Fourier transform mirror 4c' are sequentially arranged between the pump source 2 and the output surface of the gain medium 9, and the driver is connected to the deformable mirror 4a'. The device of this embodiment is to control the deformable mirror 4a' through the driver, thereby changing the phase distribution of the pump light 3, and project the change of the phase distribution of the pump light to the light intensity distribution through the Fourier transform mirror 4c', and realize the same In order to control the light intensity distribution and aperture size of the pump light, so as to gain the laser beam, solve the problem of laser loss and damage, so that the light intensity of the pump light on the exit surface of the gain medium is within the tolerance range of the predetermined value, The gain distribution in the gain medium is controlled, so that the light intensity distribution of the laser beam can be modulated into a uniform distribution or a Gaussian distribution.

The present invention also provides a laser gain method, in which a gain medium that receives pumping light is provided on the optical path of the laser, and the pumping light enters the gain medium through an optical element connected to a controller, and the controller controls The light intensity distribution of the pump light passing through the optical element makes the light intensity distribution of the pump light before it enters the gain medium within the tolerance range of the preset value, so as to control the gain distribution in the gain medium, so as to realize the light intensity of the laser The strong distribution is modulated as a uniform distribution or a Gaussian distribution. This method uses the controller to control the light intensity of the pump light passing through the optical element, thereby gaining the laser beam and solving the problem of laser loss and damage, so that the laser beam can become a preset shape, which can be a commonly used uniform distribution or a Gaussian distribution.

In the laser gain method of the present invention, a gain medium that receives the pump light is provided on the optical path of the laser, and the gain distribution generated by the pump light entering the gain medium through the liquid crystal light valve controlled by the driver is g(x, y, z), The driver controls the light intensity distribution of the pump light passing through the liquid crystal light valve, thereby changing the gain medium, and the relationship between the light intensity distribution of the pump light and the gain distribution can be expressed as:

$\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; hc</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The method of the invention can control the light intensity distribution of the pumping light into any shape. Preferably, the light intensity of the pump light on the exit surface of the gain medium is within the tolerance range of _IpH (x, y) or _IpG (x, y), that is, the light intensity of the exit surface of the gain medium is within _IpH (x, y) or the upper and lower limits of _IpG (x, y), which are equal in exceptional cases.

in:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; pH</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; In</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; In</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; pG</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; In</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="x"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">x</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">y</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; In</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">y</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

A₀为激光的光强振幅，I_i(x，y)为入射激光光强分布，x、y为空间坐标，

为饱和光强，λ_l为激光波长，λ_p为泵浦光的波长，h为普朗克常量，c为光速，σ₂₁为增益介质的受激发射截面，τ_f为激活离子的上能级寿命，α为增益介质对泵浦光的吸收系数，L为增益介质的长度，ω为高斯光束束腰参数，e为欧拉系数。In the formula,

A ₀ is the light intensity amplitude of the laser, I _i (x, y) is the incident laser light intensity distribution, x, y are the spatial coordinates,

is the saturation light intensity, λ _l is the laser wavelength, λ _p is the wavelength of the pump light, h is Planck’s constant, c is the speed of light, σ ₂₁ is the stimulated emission cross section of the gain medium, τ _f is the upper energy of the activated ion α is the absorption coefficient of the gain medium for the pump light, L is the length of the gain medium, ω is the Gaussian beam waist parameter, and e is the Euler coefficient.

When the laser gain method of the present invention uses an optical element comprising a liquid crystal light valve, a lens group and a reflector, the laser gain method realizes the laser gain process as follows:

First, when the pump source is not turned on, start the laser source, and record the light intensity distribution at this time as I _i (x, y);

Secondly, use the formula (2) or (3) to calculate the distribution I _p (x, y) of the pump light that should be applied to the exit surface of the gain medium; turn on the pump source, and use the driver to control the liquid crystal light valve to change The outgoing light intensity distribution of the pump light, and adjust the lens group, so that the distribution of the pump light on the surface of the gain medium is as close as possible to I _pH (x, y) or I _pG (x, y), that is, at I _pH (x , y) or I _pG (x, y) within the tolerance range, a nearly uniform or Gaussian light intensity distribution can be obtained.

When the light intensity distribution of the cross-section of the laser beam from the incident surface of the gain medium is uniformly distributed, at this time, $I_o(x,\mathrm{the\; y})=\left\{\begin{array}{c}{A}_0,x^2+{\mathrm{the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">y</figure-callout>}}^2\&le;{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">r</figure-callout>}}^2\\ 0,x^2+{\mathrm{the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000136247610000011.png,HDA0000136247610000031.png"\; state="\{\{state\}\}">y</figure-callout>}}^2>r\end{array}\right.,$ At this time, the distribution of the pump light emitted by the gain medium is within the tolerance range of I _pH (x, y), A ₀ is the light intensity amplitude of the laser, and r is the radius of the laser beam.

这时增益介质出射面的泵浦光的分布为I_pG(x，y)容限范围内。When the light intensity distribution of the cross-section of the laser beam exiting from the exit surface of the gain medium is a Gaussian distribution

At this time, the distribution of the pump light on the output surface of the gain medium is within the tolerance range of I _pG (x, y).

When the laser gain method of the present invention uses optical elements including deformable mirrors, Fourier transform mirrors and reflection mirrors, the method of the present invention is to change the phase distribution of the pump light through the driver to control the deformable mirrors, and to pump the pump light through the Fourier transform mirrors. The change of the phase distribution of the Pu light is projected onto the light intensity distribution I _p (x, y), and the relationship between them is:

Among them, FT() is the Fourier transform operator; I _p0 (x, y) and φ ₀ (x, y) are the intensity distribution and phase distribution of the pump light, which can be measured before the device is built; Δφ (x, y) is the phase distribution introduced by the deformable mirror, i is the imaginary unit, and k is the pump light wave vector. Therefore, in this embodiment, only by adjusting the phase distribution Δφ(x, y) introduced by the deformable mirror, the light intensity distribution I _p (x, y) of the pump light at the gain medium tends to the formula (2) , I _pH (x, y) or I _pG (x, y) in (3), the light intensity distribution of the incident laser can be transformed into a uniform distribution or a Gaussian distribution.

It can be seen from the above embodiments that the embodiments of the present invention control the light intensity distribution of the pump light passing through the optical element through the controller, thereby gaining the laser beam and solving the problem of laser loss and damage in the control of laser light intensity distribution , so that the light intensity of the pump light on the exit surface of the gain medium is within the tolerance range of a predetermined value, so as to control the gain distribution in the gain medium, so as to realize the modulation of the light intensity distribution of the laser beam to a uniform distribution or a Gaussian distribution. In this method, by controlling the pump light so that the distribution of the pump light on the surface of the gain medium is within the tolerance range of I _pH (x, y) or I _pG (x, y), a nearly uniform or Gaussian laser can be obtained. light intensity distribution.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and replacements can also be made, these improvements and replacements It should also be regarded as the protection scope of the present invention.

Claims (8)

1. A laser gain device is characterized by comprising a gain medium, a pumping source, an optical element and a controller, wherein the gain medium is arranged on a laser light path and receives pumping light emitted by the pumping source;

the controller controls the pump light to enter the gain mediumThe front light intensity is I_pH(x, y) within a tolerance range, wherein, $I_{\mathrm{pH}}(x,y)=C_p\&CenterDot;[\mathrm{In}{A}_0-\mathrm{In}\left(I_i(x,y)\right)+\frac{A_0-I_i(x,y)}{I_s}],$

in the formula,

A₀is the light intensity amplitude of the laser, I_i(x, y) is the light intensity distribution of the laser on the incident surface of the gain medium,λ_lis the wavelength of the laser, λ_pH is the Planck constant, c is the speed of light, σ is the wavelength of the pump light₂₁Is the stimulated emission cross section of the gain medium, tau_fIn order to activate the upper energy level life of ions, alpha is the absorption coefficient of the gain medium to pump light, L is the length of the gain medium, x and y are space coordinates, and e is an Euler coefficient; or:

the above-mentionedThe controller controls the light intensity of the pump light before the pump light enters the gain medium to be I_pG(x, y) within a tolerance range, wherein,

$I_{\mathrm{pG}}(x,y)=C_p\&CenterDot;[\mathrm{In}{A}_0-\left(\frac{x^2+y^2}{{\mathrm{\&omega;}}^2}\right)-\mathrm{In}\left(I_i(x,y)\right)+\frac{A_0{e}^{-\frac{x^2+y^2}{{\mathrm{\&omega;}}^2}}-I_i(x,y)}{I_s}],$

in the formula,

A₀is the light intensity amplitude of the laser, I_i(x, y) is the light intensity distribution of the laser on the incident surface of the gain medium,

λ_lis the wavelength of the laser, λ_pH is the Planck constant, c is the speed of light, σ is the wavelength of the pump light₂₁Is the stimulated emission cross section of the gain medium, tau_fIn order to activate the upper energy level life of ions, alpha is the absorption coefficient of the gain medium to pump light, L is the length of the gain medium, x and y are space coordinates, omega is the beam waist parameter of a Gaussian beam, and e is the Euler coefficient.

2. The apparatus of claim 1, wherein the optical element comprises a liquid crystal light valve, a lens set and a mirror, the liquid crystal light valve, the lens set and the mirror are sequentially disposed between the pumping source and the gain medium, and the controller is connected to the liquid crystal light valve.

3. The apparatus of claim 1, wherein the optical element comprises an anamorphic mirror and a fourier transform mirror, the anamorphic mirror and the fourier transform mirror being disposed in sequence between the pump source and the gain medium, the controller being connected to the anamorphic mirror.

4. The apparatus of any of claims 1-3, wherein the gain medium is Nd: YVO 4.

5. A laser gain method is characterized in that a gain medium for receiving pump light is arranged on a laser light path, the pump light enters the gain medium through an optical element connected with a controller, the controller controls the light intensity distribution of the pump light passing through the optical element, so that the light intensity distribution of the pump light before entering the gain medium is within the tolerance range of a preset value, the gain distribution in the gain medium is controlled, and the light intensity distribution of the laser light is modulated into uniform distribution or Gaussian distribution;

the controller controls the light intensity of the pump light before the pump light enters the gain medium to be I_pH(x, y) within a tolerance range, wherein, $I_{\mathrm{pH}}(x,y)=C_p\&CenterDot;[\mathrm{In}{A}_0-\mathrm{In}\left(I_i(x,y)\right)+\frac{A_0-I_i(x,y)}{I_s}],$

in the formula,

A₀is the light intensity amplitude of the laser, I_i(x, y) is the light intensity distribution of the laser on the incident surface of the gain medium,

λ_lis the wavelength of the laser, λ_pH is the Planck constant, c is the speed of light, σ is the wavelength of the pump light₂₁Is the stimulated emission cross section of the gain medium, tau_fIn order to activate the upper energy level life of ions, alpha is the absorption coefficient of the gain medium to pump light, L is the length of the gain medium, x and y are space coordinates, and e is an Euler coefficient; or:

the controller controls the light intensity of the pump light before the pump light enters the gain medium to be I_pG(x, y) within a tolerance range, wherein,

$I_{\mathrm{pG}}(x,y)=C_p\&CenterDot;[\mathrm{In}{A}_0-\left(\frac{x^2+y^2}{{\mathrm{\&omega;}}^2}\right)-\mathrm{In}\left(I_i(x,y)\right)+\frac{A_0{e}^{-\frac{x^2+y^2}{{\mathrm{\&omega;}}^2}}-I_i(x,y)}{I_s}],$

in the formula,

A₀is the light intensity amplitude of the laser, I_i(x, y) is the light intensity distribution of the laser on the incident surface of the gain medium,

λ_lis the wavelength of the laser, λ_pH is the Planck constant, c is the speed of light, σ is the wavelength of the pump light₂₁Is the stimulated emission cross section of the gain medium, tau_fIn order to activate the upper energy level life of ions, alpha is the absorption coefficient of the gain medium to pump light, L is the length of the gain medium, x and y are space coordinates, omega is the beam waist parameter of a Gaussian beam, and e is the Euler coefficient.

6. The method of claim 5, further comprising the step of recording an incident intensity of the laser light, wherein the laser light source is turned on with the pump source turned off, and an intensity distribution I at an incident surface of the gain medium at the time is recorded_i(x, y), and calculating the light intensity I of the pump light before the pump light enters the gain medium_PHOr I_PGIs controlled by a controller to control the intensity of the pump light via the optical element such that the pumpThe light intensity of the Puguang is I before entering the gain medium_PHOr I_PGWithin the tolerance range of (c).

7. The method according to any of claims 5-6, wherein the optical element comprises a liquid crystal shutter, a lens group and a mirror, the liquid crystal shutter, the lens group and the mirror are arranged between the pumping source and the exit surface of the gain medium in sequence, and the controller is connected with the liquid crystal shutter.

8. The method according to any of claims 5-6, wherein the optical element comprises an anamorphic mirror and a Fourier transform mirror, the anamorphic mirror and the Fourier transform mirror being arranged in sequence between the pump source and the exit face of the gain medium, the controller being connected to the anamorphic mirror.

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