CN118336499B - Self-stabilizing laser device and output method - Google Patents

Abstract

The invention provides a self-stabilizing laser device and an output method, which relate to the technical field of laser and comprise a right-angle prism, a wedge-shaped prism, a saturable absorber, a laser gain crystal, an output mirror, a beam splitter, a pumping source controller, a beam analyzer, a feedback controller and a motor. The invention adopts the wedge prism and the right angle prism to cooperate, on one hand, the wedge prism is adopted to achieve the effect of equal optical path length of the round trip path in the resonant cavity, and eliminate the beam drift caused by the thermal effect. On the other hand adopts the right angle prism simultaneously, utilizes the characteristics that right angle prism can be used for gathering the light together in the different directions, not only can adjust the drift of light beam, in the resonant cavity is returned to the light beam reflection that will drift, increases the beam quality of output light, can also effectively improve laser output's stability, arouses the resonant cavity detuning to external vibration, temperature stress variation. The quality stability and the high-precision directivity of the laser output beam are improved, and the applicability of the laser device is expanded.

Description

Self-stabilizing laser device and output method

Technical Field

The present invention generally relates to the field of laser technology, and in particular to a self-stabilizing laser device and an output method.

Background Art

Solid-state lasers have the characteristics of high conversion efficiency, compact device structure, small size, high reliability, and large output energy. They are the main development direction of current laser technology and are widely used in many fields such as military, processing, and medical treatment.

Solid-state lasers often use side pumping to pump laser gain crystals. Side pumping generally uses high-power, large-light-emitting semiconductor laser arrays, and is widely used in high-power laser output fields such as lidar, optoelectronic countermeasures, and laser diagnosis. At the same time, the gain area in the laser working medium is large, and local high temperatures will appear inside the crystal, resulting in uneven heat distribution. Side pumping also has problems such as uneven output energy distribution and low energy extraction efficiency. This is because the pump light of the side pump enters the crystal in the radial direction, which will cause uneven distribution of the pump light and make it difficult for the gain distribution in the working material to match the intrinsic fundamental mode of the laser resonant cavity, which will lead to serious thermal effects and poor output beam quality.

Usually, the laser beam emitted by the side-pumped laser has a Gaussian distribution in the spatial plane. When the Gaussian pump light acts on the inside of the laser gain crystal, the heat distribution in the crystal also has a certain temperature gradient. Under the action of heat, the crystal undergoes a slight deformation on the surface, causing the output laser beam to drift slightly. Therefore, a technical solution is needed to improve the stability and pointing accuracy of the laser output beam.

Summary of the invention

In order to solve the problems of poor stability and poor pointing accuracy of output laser beams, the present invention provides a self-stabilizing laser device and an output method.

As shown in Figure 1, a self-stabilizing laser device provided according to an embodiment of the first aspect of the present invention includes a right-angle prism 1, a wedge prism 2, a saturable absorber 3, a laser gain crystal 4, an output mirror 5, a beam splitter 6, a pump source 7, a pump source controller 8, a beam analyzer 9, a feedback controller 10, and a motor 11.

Specifically, the self-stabilized laser device includes, from left to right, a right-angle prism 1, a wedge prism 2, a saturable absorber 3, a laser gain crystal 4, an output mirror 5, and a beam splitter 6;

The pump source 7 is an independent structure or a group of closely arranged structures. The pump source 7 is correspondingly arranged on the side of the laser gain crystal 4 to provide pump light to the laser gain crystal 4 in the lateral direction.

The output wavelength of the pump source 7 corresponds to the absorption wavelength of the laser gain crystal 4, so that the laser gain crystal 4 undergoes population inversion;

The right-angle prism 1 and the output mirror 5 serve as laser resonant cavity mirrors, and the laser light after gain oscillation is output along the output mirror 5;

The beam splitter 6 is arranged along the optical path behind the output mirror 5 to divide the output laser into two paths, the horizontal direction and the vertical direction, wherein the horizontal direction is the optical path required for work, and the vertical direction is the detection optical path, and the laser in the vertical direction is incident on the beam analyzer 9;

The beam profiler 9 is electrically connected to the feedback controller 10, and the feedback controller 10 is electrically connected to the motor 11;

The beam analyzer 9 analyzes the spot condition of the incident laser and transmits the analysis result to the feedback controller 10, and the feedback controller 10 outputs a control signal to the motor 11;

The motor 11 is connected to the wedge prism 2 to control the movement of the wedge prism 2 between a first position A and a second position B; the first position A is the position of the wedge prism 2 before it enters the laser light path, and the second position B is the position of the wedge prism 2 when the output laser spot is a fundamental mode after the wedge prism 2 enters the laser light path.

Specifically, the laser gain crystal 4 is made of Nd:YAG crystal, Nd:YAP crystal or Nd:YVO ₄ crystal; the wavelength of the pump light emitted by the pump source 7 is 808 nm.

The absorption wavelength of the Nd:YAG crystal, Nd:YAP crystal or Nd:YVO ₄ crystal is 808 nm, and the output wavelength of the pump source is set to 808 nm to achieve population inversion of the laser gain crystal.

Specifically, the saturable absorber 3 adopts Cr ⁴⁺ :YAG crystal. In the initial state, the initial transmittance of the saturable absorber 3 is low, the loss in the laser resonant cavity is large, and laser oscillation cannot be formed; under the action of pump light, the number of upper energy level particles in the gain medium continues to increase, the laser light intensity increases, the transmittance of the saturable absorber 3 increases, the loss in the cavity decreases, the laser oscillates back and forth in the resonant cavity, and when the saturable absorber 3 reaches saturation, passive Q switching is turned on to form a laser pulse.

Specifically, the surface of the right-angle prism 1 is coated with a high-reflection film of the output laser wavelength, and the two end surfaces of the laser gain crystal 4 are coated with an anti-reflection film of the output laser wavelength; the output mirror 5 is coated with an anti-reflection film of the output laser wavelength; the beam splitter 6 is coated with a partial reflection film of the output laser wavelength, and preferably, the reflectivity of the partial reflection film is 1%-10%.

Specifically, the right-angle prism 1, the output mirror 5, and the beam splitter 6 are made of CaF ₂ crystal.

Specifically, the output method of the self-stabilizing laser device includes:

The motor 11 is used to adjust the wedge-shaped prism 2 to be located at a first position A, that is, a position where the wedge-shaped prism 2 does not enter the optical path of the resonant cavity;

The pump source 7 is located on the side of the laser gain crystal 4, and the pump source 7 emits pump light;

Under the action of the pump light, the particles in the laser gain crystal 4 absorb the pump light and undergo energy level transition. Through energy transfer between energy levels, the particles are excited to the upper energy level, and the particle number inversion is achieved in the laser gain crystal 4.

The saturable absorber 3 first puts the resonant cavity in a high-loss mode. In the initial state, the initial transmittance of the saturable absorber 3 is low, the loss in the laser resonant cavity is large, and laser oscillation cannot be formed; under the action of pump light, the number of upper energy level particles in the gain medium continues to increase, the laser light intensity increases, the transmittance of the saturable absorber 3 increases, the loss in the cavity decreases, and the laser oscillates back and forth in the resonant cavity. When the saturable absorber 3 reaches saturation, passive Q switching is turned on to form a laser pulse;

When the pump light acts on the laser gain crystal 4, the laser gain crystal 4 undergoes a slight deformation on the surface due to the temperature gradient under the action of the thermal effect, causing the output laser beam to drift;

The output laser enters the beam analyzer 9 after passing through the beam splitter 6. The beam analyzer 9 analyzes the output laser beam and transmits the analysis result to the feedback controller 10 in real time.

The feedback controller 10 controls the motor 11 to adjust the position of the wedge prism 2, so that the wedge prism 2 moves from the first position A toward the optical path and enters the optical path, thereby adjusting the distance by which the wedge prism 2 is inserted into the resonant cavity;

By adjusting the wedge-shaped prism 2, the drifting laser pulse can enter the right-angle prism 1 to correct the output laser;

During the movement of the wedge-shaped prism 2, the output laser beam spot is detected in real time by the beam analyzer 9. When it is detected that the output laser beam spot is a fundamental mode spot, the feedback controller 10 controls the motor 11 to stop. At this time, the position of the wedge-shaped prism 2 is the second position B.

The self-stabilizing laser device and output method proposed in the present invention adopt the side pumping method and make full use of the laser gain crystal to obtain high-power, high-energy, and high-conversion-efficiency laser output. The single-sided heat transfer structure is realized by the side pumping of a single pump source to form a unidirectional temperature gradient. The wedge-shaped prism and the right-angle prism are used in combination. On the one hand, the wedge-shaped prism is used to achieve the effect of equal optical path in the round-trip path in the resonant cavity, eliminating the beam drift caused by thermal effects. On the other hand, the right-angle prism is used at the same time. The right-angle prism can be used to converge light in different directions together. It can not only adjust the drift of the light beam, reflect the drifting light beam back into the resonant cavity, and increase the beam quality of the output light, but also effectively improve the stability of the laser output, and resist the misalignment of the resonant cavity caused by external vibration and temperature stress changes. This scheme improves the beam quality stability and high-precision directivity of the laser output, and expands the applicability of the laser device.

It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, advantages and aspects of the embodiments of the present invention will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

FIG. 1 is a schematic diagram of the structure of a self-stabilizing laser device.

The corresponding relationship between the reference numerals and component names in FIG. 1 is as follows:

1 right angle prism, 2 wedge prism, 3 saturable absorber, 4 laser gain crystal, 5 output mirror, 6 beam splitter, 7 pump source, 8 pump source controller, 9 beam analyzer, 10 feedback controller, 11 motor, A first position, B second position.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In addition, the term "and/or" in this article is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.

In the present invention, the wedge prism and the right-angle prism are used in combination, which can not only adjust the drift of the light beam and reflect the drifted light beam back into the resonant cavity to increase the beam quality of the output light, but also effectively improve the stability of the laser output and resist the misalignment of the resonant cavity caused by external vibration and temperature stress changes.

The self-stabilizing laser device provided by an embodiment of the present invention is described below with reference to FIG. 1 .

As shown in Figure 1, a self-stabilizing laser device provided according to an embodiment of the first aspect of the present invention includes a right-angle prism 1, a wedge prism 2, a saturable absorber 3, a laser gain crystal 4, an output mirror 5, a beam splitter 6, a pump source 7, a pump source controller 8, a beam analyzer 9, a feedback controller 10, and a motor 11.

Specifically, the self-stabilized laser device includes, from left to right, a right-angle prism 1, a wedge prism 2, a saturable absorber 3, a laser gain crystal 4, an output mirror 5, and a beam splitter 6;

The pump source 7 is an independent structure or a group of closely arranged structures. The pump source 7 is correspondingly arranged on the side of the laser gain crystal 4 to provide pump light to the laser gain crystal 4 in the lateral direction.

The output wavelength of the pump source 7 corresponds to the absorption wavelength of the laser gain crystal 4, so that the laser gain crystal 4 undergoes population inversion;

The right-angle prism 1 and the output mirror 5 serve as laser resonant cavity mirrors, and the laser light after gain oscillation is output along the output mirror 5;

The beam splitter 6 is arranged along the optical path behind the output mirror 5 to divide the output laser into two paths, the horizontal direction and the vertical direction, wherein the horizontal direction is the optical path required for work, and the vertical direction is the detection optical path, and the laser in the vertical direction is incident on the beam analyzer 9;

The beam profiler 9 is electrically connected to the feedback controller 10, and the feedback controller 10 is electrically connected to the motor 11;

The beam analyzer 9 analyzes the spot condition of the incident laser and transmits the analysis result to the feedback controller 10, and the feedback controller 10 outputs a control signal to the motor 11;

The motor 11 is connected to the wedge prism 2 to control the movement of the wedge prism 2 between a first position A and a second position B; the first position A is the position of the wedge prism 2 before it enters the laser light path, and the second position B is the position of the wedge prism 2 when the output laser spot is a fundamental mode after the wedge prism 2 enters the laser light path.

In some embodiments, the laser gain crystal 4 is made of Nd:YAG crystal, Nd:YAP crystal or Nd:YVO ₄ crystal; the wavelength of the pump light emitted by the pump source 7 is 808 nm.

In these embodiments, the absorption wavelength of the Nd:YAG crystal, Nd:YAP crystal or Nd:YVO ₄ crystal is 808 nm, and the output wavelength of the pump source is set to 808 nm to achieve population inversion of the laser gain crystal.

In some embodiments, the saturable absorber 3 adopts Cr ⁴⁺ :YAG crystal. In the initial state, the initial transmittance of the saturable absorber 3 is low, the loss in the laser resonant cavity is large, and laser oscillation cannot be formed; under the action of pump light, the number of upper energy level particles in the gain medium continues to increase, the laser light intensity increases, the transmittance of the saturable absorber 3 increases, the loss in the cavity decreases, the laser oscillates back and forth in the resonant cavity, and when the saturable absorber 3 reaches saturation, passive Q switching is turned on to form a laser pulse.

In some embodiments, the surface of the right-angle prism 1 is coated with a high-reflection film of the output laser wavelength, and the two end surfaces of the laser gain crystal 4 are coated with an anti-reflection film of the output laser wavelength; the output mirror 5 is coated with an anti-reflection film of the output laser wavelength; the beam splitter 6 is coated with a partial reflection film of the output laser wavelength, and preferably, the reflectivity of the partial reflection film is 1%-10%.

In some embodiments, the right-angle prism 1, the output mirror 5, and the beam splitter 6 are made of CaF ₂ crystal.

In some embodiments, the output method of the self-stabilized laser device includes:

The motor 11 is used to adjust the wedge-shaped prism 2 to be located at a first position A, that is, a position where the wedge-shaped prism 2 does not enter the optical path of the resonant cavity;

The pump source 7 is located on the side of the laser gain crystal 4, and the pump source 7 emits pump light;

Under the action of the pump light, the particles in the laser gain crystal 4 absorb the pump light and undergo energy level transition. Through energy transfer between energy levels, the particles are excited to the upper energy level, and the particle number inversion is achieved in the laser gain crystal 4.

The saturable absorber 3 first puts the resonant cavity in a high-loss mode. In the initial state, the initial transmittance of the saturable absorber 3 is low, the loss in the laser resonant cavity is large, and laser oscillation cannot be formed; under the action of pump light, the number of upper energy level particles in the gain medium continues to increase, the laser light intensity increases, the transmittance of the saturable absorber 3 increases, the loss in the cavity decreases, and the laser oscillates back and forth in the resonant cavity. When the saturable absorber 3 reaches saturation, passive Q switching is turned on to form a laser pulse;

When the pump light acts on the laser gain crystal 4, the laser gain crystal 4 undergoes a slight deformation on the surface due to the temperature gradient under the action of the thermal effect, causing the output laser beam to drift;

The output laser enters the beam analyzer 9 after passing through the beam splitter 6. The beam analyzer 9 analyzes the output laser beam and transmits the analysis result to the feedback controller 10 in real time.

The feedback controller 10 controls the motor 11 to adjust the position of the wedge prism 2, so that the wedge prism 2 moves from the first position A toward the optical path and enters the optical path, thereby adjusting the distance by which the wedge prism 2 is inserted into the resonant cavity;

By adjusting the wedge-shaped prism 2, the drifting laser pulse can enter the right-angle prism 1 to correct the output laser;

During the movement of the wedge-shaped prism 2, the output laser beam spot is detected in real time by the beam analyzer 9. When it is detected that the output laser beam spot is a fundamental mode spot, the feedback controller 10 controls the motor 11 to stop. At this time, the position of the wedge-shaped prism 2 is the second position B.

According to the embodiments of the present invention, the following technical effects are achieved: the self-stabilizing laser device and output method provided by the embodiments of the present invention adopt the side pumping technology, make full use of the laser gain crystal, to ensure that most of the laser gain crystal is effectively excited by the pump source, so as to achieve high-power, high-energy and high-conversion-efficiency laser output. Specifically, the single-sided heat transfer structure is realized by the side pumping of a single pump source to form a unidirectional temperature gradient, and the wedge prism and the right-angle prism are used in combination. On the one hand, the wedge prism is used to achieve the effect of equal optical path in the round-trip path in the resonant cavity, eliminating the beam drift caused by thermal effect. On the other hand, the right-angle prism is used at the same time, and the right-angle prism can be used to converge light in different directions together, which can not only adjust the drift of the light beam, reflect the drifting light beam back into the resonant cavity, and increase the beam quality of the output light, but also effectively improve the stability of the laser output, and resist the imbalance of the resonant cavity caused by external vibration and temperature stress changes.

In the description of this specification, the terms "connection", "installation", "fixation" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In the description of this specification, the description of the terms "one embodiment", "some embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. A method for outputting a self-stabilizing laser device is characterized in that,

The self-stabilization laser device comprises a right angle prism (1), a wedge prism (2), a saturable absorber (3), a laser gain crystal (4), an output mirror (5), a beam splitter (6), a pump source (7), a pump source controller (8), a beam analyzer (9), a feedback controller (10) and a motor (11);

The self-stabilization laser device sequentially comprises a right-angle prism (1), a wedge-shaped prism (2), a saturable absorber (3), a laser gain crystal (4), an output mirror (5) and a beam splitter (6) from left to right;

The pumping source (7) is of an independent structure or a group of closely arranged structures, the pumping source (7) is correspondingly arranged on the side face of the laser gain crystal (4), and pumping light is provided for the laser gain crystal (4) along the side direction;

the output wavelength of the pump source (7) corresponds to the absorption wavelength of the laser gain crystal (4), so that the laser gain crystal (4) generates particle number inversion;

the right-angle prism (1) and the output mirror (5) are used as laser resonant cavity mirrors, and laser after gain oscillation is output along the output mirror (5);

The beam splitter (6) is arranged behind the output mirror (5) along an optical path to split output laser into two paths of horizontal direction and vertical direction, wherein the horizontal direction is an optical path required by work, the vertical direction is a detection optical path, and the laser in the vertical direction is incident to the beam analyzer (9);

The beam analyzer (9) is electrically connected with the feedback controller (10), and the feedback controller (10) is electrically connected with the motor (11);

The beam analyzer (9) analyzes the light spot condition of the incident laser and transmits an analysis result to the feedback controller (10), and the feedback controller (10) outputs a control signal to the motor (11);

The motor (11) is connected with the wedge-shaped prism (2) and controls the wedge-shaped prism (2) to move between a first position A and a second position B; the first position A is a position where the wedge-shaped prism (2) does not enter a laser light path, and the second position B is a position of the wedge-shaped prism (2) when the output laser light spot is a fundamental mode after the wedge-shaped prism (2) enters the laser light path;

The output method of the self-stabilizing laser device comprises the following steps:

The wedge-shaped prism (2) is adjusted to be positioned at a first position A by the motor (11), namely, the position of the wedge-shaped prism (2) which does not enter a resonant cavity light path;

the pumping source (7) is positioned on the side surface of the laser gain crystal (4), and the pumping source (7) emits pumping light;

Under the action of pumping light, the particles absorb the pumping light to generate energy level transition in the laser gain crystal (4), the particles are excited to an upper energy level through energy transfer between the energy levels, and the population inversion is realized in the laser gain crystal (4);

The saturable absorber (3) enables the resonant cavity to be in a high-loss mode, and in an initial state, the initial transmittance of the saturable absorber (3) is low, the loss in the laser resonant cavity is high, and laser oscillation cannot be formed; under the action of pumping light, the upper energy level particle number in the gain medium is continuously increased, the laser light intensity is increased, the transmittance of the saturable absorber (3) is increased, the loss in the cavity is reduced, the laser oscillates reciprocally in the resonant cavity, and when the saturable absorber (3) reaches saturation, the passive Q-switching is started to form laser pulses;

When pump light acts on the laser gain crystal (4), the laser gain crystal (4) generates tiny deformation on the surface due to the temperature gradient under the action of a thermal effect, so that an output laser beam can drift;

The output laser enters the beam analyzer (9) after passing through the beam splitter (6), and the beam analyzer (9) analyzes the output laser beam and transmits the analysis result to the feedback controller (10) in real time;

The feedback controller (10) controls the motor (11) to adjust the position of the wedge-shaped prism (2) so that the wedge-shaped prism (2) moves from the first position A to the direction of the optical path and enters the optical path, and then the distance of the wedge-shaped prism (2) inserted into the resonant cavity is adjusted;

the drifting laser pulse can enter the right-angle prism (1) through adjustment of the wedge-shaped prism (2), and output laser is corrected;

in the moving process of the wedge-shaped prism (2), detecting an output laser beam spot in real time through the beam analyzer (9), and controlling a motor (11) to stop through the feedback controller (10) when detecting that the output laser spot is a fundamental mode spot, wherein the position of the wedge-shaped prism (2) is a second position B;

The wedge-shaped prism (2) is matched with the right-angle prism (1), on one hand, the wedge-shaped prism (2) is adopted to achieve the effect of equal optical path length of a round trip path in a resonant cavity, and the beam drift caused by the thermal effect is eliminated; on the other hand adopts simultaneously right angle prism (1), utilizes right angle prism (1) can be used for gathering the characteristics together of light on the different directions, not only can adjust the drift of light beam, in the resonant cavity is returned to the light beam reflection that will drift, increase the beam quality of output light, can also effectively improve laser output's stability, and the external vibration of resistance, temperature stress change arouse the resonant cavity detuning.

2. The output method of a self-stabilizing laser device according to claim 1, wherein said laser gain crystal (4) is a nd:yag crystal, nd:yap crystal, or nd:yvo ₄ crystal; the wavelength of the pumping light emitted by the pumping source (7) is 808nm.

3. The method according to claim 2, wherein the saturable absorber (3) is a Cr ⁴⁺:yag crystal, and in an initial state, the initial transmittance of the saturable absorber (3) is low, the loss in the laser resonator is high, and laser oscillation cannot be formed; under the action of pumping light, the upper energy level particle number in the gain medium is continuously increased, the laser light intensity is increased, the transmittance of the saturable absorber (3) is increased, the loss in the cavity is reduced, the laser oscillates reciprocally in the resonant cavity, and when the saturable absorber (3) reaches saturation, the passive Q-switching is started to form laser pulses.

4. The method for outputting the self-stabilized laser device according to claim 3, wherein the surface of the right-angle prism (1) is plated with a high reflection film for outputting the laser wavelength, and both end surfaces of the laser gain crystal (4) are plated with an antireflection film for outputting the laser wavelength; the output mirror (5) is plated with an antireflection film for outputting laser wavelength; the beam splitter (6) is plated with a partial reflecting film for outputting laser wavelength.

5. The output method of a self-stabilizing laser device according to claim 4, wherein the reflectivity of said partially reflecting film is 1% -10%.

6. The method according to claim 4, wherein the right angle prism (1), the output mirror (5) and the beam splitter (6) are CaF ₂ crystals.