Outside-cavity frequency doubling continuous green laser

Abstract

The invention provides an extra-cavity frequency doubling continuous green laser. The extra-cavity frequency doubling continuous green laser comprises a light source used for generating pump light, a resonant cavity assembly, a polarization beam splitter, a frequency doubling element and a reflector assembly. The resonant cavity assembly is used for receiving pump light generated by the light source and converting the pump light into non-polarization-maintaining infrared laser; the polarization beam splitter is used for splitting the non-polarization-maintaining infrared laser into a first path of polarization infrared laser and a second path of polarization infrared laser; the reflector assembly is used for respectively changing the light path directions of the first path of polarized infrared laser and the second path of polarized infrared laser; the frequency doubling element is used for converting at least part of the first path of polarized infrared laser and at least part of the second path of polarized infrared laser into green laser; and the reflector assembly is also used for transmitting the first path of residual polarized infrared laser and the second path of residual polarized infrared laser to the polarization beam splitter and outputting the first path of residual polarized infrared laser and the second path of residual polarized infrared laser through the polarization beam splitter. According to the out-of-cavity frequency doubling continuous green laser provided by the embodiment of the invention, the frequency doubling efficiency, stability and safety of the green laser can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of laser technology, and more particularly, to an extracavity frequency-doubled continuous green laser. Background Art

[0002] Continuous green lasers have attracted much attention due to their wide applications in fields such as metal welding and metal printing. In order to reduce costs, non-polarization-maintaining infrared lasers are usually used as the frequency-doubling light source for generating green lasers. However, although this method reduces costs, the frequency-doubling efficiency of generating green light is relatively low, and the stability and safety are poor. Therefore, how to ensure the frequency-doubling efficiency, stability, and safety of green lasers has become an urgent problem to be solved. Summary of the Invention

[0003] The embodiments of the present disclosure at least provide an extracavity frequency-doubled continuous green laser, which can not only improve the frequency-doubling efficiency of green lasers, but also improve the stability and safety of generating green lasers.

[0004] The embodiments of the present disclosure provide an extracavity frequency-doubled continuous green laser, including a light source for generating pump light, a resonant cavity assembly, a polarization beam splitter, a frequency-doubling element, and a mirror assembly;

[0005] The resonant cavity assembly is configured to receive the pump light generated by the light source and convert the pump light into non-polarization-maintaining infrared laser;

[0006] The polarization beam splitter is disposed on the transmission optical path of the non-polarization-maintaining infrared laser and is configured to split the non-polarization-maintaining infrared laser into a first polarized infrared laser and a second polarized infrared laser that are respectively transmitted along a first optical path direction and a second optical path direction; the polarization directions of the first polarized infrared laser and the second polarized infrared laser are different; the first optical path direction is the same as the optical path direction of the non-polarization-maintaining infrared laser, and the second optical path direction is perpendicular to the optical path direction of the non-polarization-maintaining infrared laser;

[0007] The mirror assembly is configured to respectively change the first optical path direction of the first polarized infrared laser and the second optical path direction of the second polarized infrared laser, so that the first polarized infrared laser and the second polarized infrared laser respectively enter the frequency-doubling element from opposite sides of the frequency-doubling element;

[0008] The frequency-doubling element is configured to convert at least part of the first polarized infrared laser into a first green laser, and convert at least part of the second polarized infrared laser into a second green laser, and output the first green laser and the second green laser through the mirror assembly;

[0009] The mirror assembly is further configured to transmit a first residual polarized infrared laser beam and a second residual polarized infrared laser beam, which are respectively output from two opposite surfaces of the frequency doubling element, to the polarization beam splitter and output them through the polarization beam splitter.

[0010] In an alternative embodiment, the mirror assembly is configured to convert the first residual polarized infrared laser beam and the second residual polarized infrared laser beam, which are respectively output from two opposite surfaces of the frequency doubling element, into a third optical path direction and a fourth optical path direction, such that the first residual polarized infrared laser beam is incident on the polarization beam splitter along the third optical path direction and output through the polarization beam splitter, and the second residual polarized infrared laser beam is incident on the polarization beam splitter along the fourth optical path direction and output through the polarization beam splitter; the third optical path direction is opposite to the second optical path direction, and the fourth optical path direction is opposite to the first optical path direction.

[0011] In an alternative embodiment, the mirror assembly includes a first mirror assembly and a second mirror assembly;

[0012] The first mirror assembly is configured to change the second polarized infrared laser beam from the second optical path direction to a fifth optical path direction, such that the second polarized infrared laser beam enters the frequency doubling element along the fifth optical path direction from the first surface of the frequency doubling element; the fifth optical path direction is parallel and in the same direction as the first optical path direction;

[0013] The second mirror assembly is configured to change the first polarized infrared laser beam from the first optical path direction to a sixth optical path direction, such that the first polarized infrared laser beam enters the frequency doubling element along the sixth optical path direction from the second surface of the frequency doubling element, which is opposite to the first surface; the sixth optical path direction is parallel and in the opposite direction to the first optical path direction.

[0014] In an alternative embodiment, the first polarized infrared laser beam is a parallel polarized light, and the second polarized infrared laser beam is a perpendicular polarized light; the first mirror assembly includes a first wave plate, and the second mirror assembly includes a second wave plate;

[0015] The first wave plate is disposed on the fifth optical path direction and near the first surface, and is configured to rotate the polarization direction of the second polarized infrared laser beam to a target polarization direction;

[0016] The second wave plate is disposed on the first optical path direction and on a side of the polarization beam splitter away from the resonant cavity assembly, and is configured to rotate the polarization direction of the first polarized infrared laser beam to the target polarization direction;

[0017] The rotation direction of the first wave plate is opposite to that of the second wave plate, and the rotation angles of the first wave plate and the second wave plate are 45 degrees.

[0018] In an optional embodiment, the mirror assembly includes a first mirror assembly and a second mirror assembly;

[0019] The first mirror assembly is configured to change the direction of the first path of residual polarized infrared laser output from the first surface of the frequency doubling element from the sixth optical path direction to the third optical path direction, so that the first path of residual polarized infrared laser is incident on the polarization beam splitter along the third optical path direction and output by the polarization beam splitter;

[0020] The second mirror assembly is configured to change the direction of the second path of residual polarized infrared laser output from the second surface of the frequency doubling element from the fifth optical path direction to the fourth optical path direction, so that the second path of residual polarized infrared laser is incident on the polarization beam splitter along the fourth optical path direction and output by the polarization beam splitter.

[0021] In an optional embodiment, the first mirror assembly further includes a first mirror and a first dichroic mirror, and the second mirror assembly further includes a second mirror and a second dichroic mirror;

[0022] The first mirror is disposed in the fifth optical path direction and on the side of the first wave plate away from the frequency doubling element, and is configured to change the second path of polarized infrared laser from the second optical path direction to the fifth optical path direction;

[0023] The first dichroic mirror is disposed in the fifth optical path direction and between the first wave plate and the frequency doubling element, and is configured to transmit infrared laser and reflect green laser;

[0024] The second mirror is disposed in the first optical path direction and on the side of the second wave plate away from the polarization beam splitter, and is configured to change the first path of polarized infrared laser from the first optical path direction to the seventh optical path direction; the seventh optical path direction is perpendicular to the first optical path direction, and the seventh optical path direction is parallel and in the same direction as the second optical path direction;

[0025] The second dichroic mirror is disposed in the sixth optical path direction and near the second surface, and is configured to reflect infrared laser and transmit green laser.

[0026] In an optional embodiment, the laser further includes:

[0027] A third wave plate is disposed on the transmission optical path of the non-polarization-maintaining infrared laser and is located between the polarization beam splitter and the resonant cavity assembly, and is used to adjust the ratio of the first polarized infrared laser and the second polarized infrared laser after beam splitting.

[0028] In an optional embodiment, the resonant cavity assembly includes a first grating, a gain fiber, and a second grating;

[0029] The first grating, as the first end of the resonant cavity, is used to receive the pump light generated by the light source;

[0030] The gain fiber is disposed on a side of the first grating away from the light source and is used to convert the pump light into a non-polarization-maintaining infrared laser;

[0031] The second grating is disposed on a side of the gain fiber away from the first grating and serves as the second end of the resonant cavity for outputting the non-polarization-maintaining infrared laser.

[0032] In an optional embodiment, the laser further includes:

[0033] A first lens is disposed between the first dichroic mirror and the frequency doubling element and is used to collimate the light beam transmitted between the first dichroic mirror and the frequency doubling element; and / or

[0034] A second lens is disposed between the frequency doubling element and the second dichroic mirror and is used to collimate the light beam transmitted between the frequency doubling element and the second dichroic mirror.

[0035] In an optional embodiment, the laser further includes:

[0036] A first window mirror is disposed on a side of the second dichroic mirror away from the frequency doubling element and is used to output the green laser light output by the second dichroic mirror; and / or

[0037] A second window mirror is disposed on a side of the polarization beam splitter away from the first mirror and is used to output the infrared laser light output by the polarization beam splitter.

[0038] The extracavity frequency doubling continuous green laser provided by the embodiments of the present disclosure adopts an extracavity frequency doubling design. Since the frequency doubling element is located outside the resonant cavity, compared with intracavity frequency doubling, it is less affected by the thermal effect, the energy loss of light is smaller, which is beneficial to improving the frequency doubling efficiency and beam quality of the green laser. At the same time, there is no need for precise alignment and coupling, effectively improving the stability of the generation of the green laser, avoiding damage to the laser caused by coupling deviation, and contributing to improving the safety of the generation of the green laser.

[0039] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, rather than limiting the technical solutions of the present disclosure.

[0040] To make the above objects, features, and advantages of the present disclosure more obvious and understandable, the following presents preferred embodiments in conjunction with the accompanying drawings and describes them in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required to be used in the embodiments. The accompanying drawings herein are incorporated into the specification and form a part of this specification. These drawings illustrate embodiments consistent with the present disclosure and, together with the specification, are used to explain the technical solutions of the present disclosure. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0042] Figure 1 Shows a principle block diagram of an extracavity frequency-doubled continuous green laser provided by an embodiment of the present disclosure;

[0043] Figure 2 Shows a structural schematic diagram of an extracavity frequency-doubled continuous green laser provided by an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] To make the objects, technical solutions, and advantages of the embodiments of the present disclosure clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present disclosure in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Usually, the components of the embodiments of the present disclosure described and illustrated in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure to be protected, but only represents the selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present disclosure.

[0045] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0046] As used herein, the term "and / or" merely describes an associated relationship and indicates that there can be three relationships. For example, A and / or B can represent three cases: A exists alone, both A and B exist simultaneously, and B exists alone. Additionally, the term "at least one" as used herein means any one of a plurality or any combination of at least two of a plurality. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set composed of A, B, and C.

[0047] In addition, the terms "first", "second", etc. in the description, claims, and the above-mentioned drawings of the embodiments of the present disclosure are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0048] It has been found through research that in order to reduce the cost of generating green light, a non-polarization-maintaining infrared laser is usually used as the frequency-doubling light source for generating green laser light, and the intracavity frequency-doubling method is used to generate green light. However, although this method reduces the cost, it is greatly affected by the thermal effect in the intracavity frequency-doubling, resulting in large energy loss of light, low frequency-doubling efficiency of generating green light, and, in addition, intracavity frequency-doubling requires precise alignment and coupling, with poor stability. Moreover, if the coupling is offset due to reasons such as vibration, it may cause damage or even burnout of the laser, affecting the safety of green light generation, and the complexity of increasing the coupling efficiency is relatively large and time-consuming. Therefore, how to ensure the frequency-doubling efficiency, stability, and safety of green laser light has become an urgent problem to be solved.

[0049] Based on the above research, the present disclosure provides an extracavity frequency-doubling continuous green laser. With the design of extracavity frequency-doubling, since the frequency-doubling element is located outside the resonant cavity, compared with intracavity frequency-doubling, it is less affected by the thermal effect and has less energy loss of light, which is beneficial to improving the frequency-doubling efficiency and beam quality of green laser light. At the same time, there is no need for precise alignment and coupling, effectively improving the stability of green laser light generation and avoiding damage to the laser caused by coupling offset, which helps to improve the safety of green laser light generation.

[0050] The following will describe an extracavity frequency-doubling continuous green laser provided by the embodiments of the present disclosure with reference to the accompanying drawings.

[0051] Please refer to Figure 1 and Figure 2 , Figure 1 which is the principle block diagram of the extracavity frequency-doubling continuous green laser provided by the embodiments of the present disclosure, Figure 2 and Figure 1As shown in the figure, the extracavity frequency-doubled continuous green laser 100 includes a light source 110, a resonant cavity assembly 120, a polarization beam splitter 130, a frequency-doubling element 140, and a mirror assembly 150.

[0052] Here, the light source 110 is used to generate pump light.

[0053] The resonant cavity assembly 120 is used to receive the pump light generated by the light source 110 and convert the pump light into non-polarization-maintaining infrared laser.

[0054] Among them, the optical path between the light source 110 and the resonant cavity assembly 120 is transmitted through an optical fiber.

[0055] In the embodiment of the present disclosure, by converting the pump light into non-polarization-maintaining infrared laser, the non-polarization-maintaining infrared laser is used as the frequency-doubling light source for generating green laser. In this way, there is no need to use polarization-maintaining devices to generate polarization-maintaining infrared laser as the frequency-doubling light source, reducing the generation difficulty and cost of the frequency-doubling light source and improving the stability of green laser generation.

[0056] The polarization beam splitter 130 is disposed on the transmission optical path of the non-polarization-maintaining infrared laser and is used to split the non-polarization-maintaining infrared laser into a first polarized infrared laser and a second polarized infrared laser that are respectively transmitted along a first optical path direction A and a second optical path direction B; the polarization directions of the first polarized infrared laser and the second polarized infrared laser are different; the first optical path direction A is the same as the optical path direction of the non-polarization-maintaining infrared laser, and the second optical path direction B is perpendicular to the optical path direction of the non-polarization-maintaining infrared laser.

[0057] In practical applications, heat is generated during the transmission and conversion of the optical path. When the heat is higher than the preset heat threshold, it is easy to generate the problem of extinction degradation ratio. The degree of linear polarization will degenerate due to the high heat, resulting in a decrease in the effective power available for frequency doubling to generate green light, affecting the output stability of the green laser.

[0058] In response to this, in the embodiment of the present disclosure, the non-polarization-maintaining infrared laser is split into two polarized infrared lasers by the polarization beam splitter 130 for transmission, avoiding the problem of extinction ratio degradation caused by high heat, and improving the effective power of frequency doubling to generate green light and the output stability of the green laser.

[0059] The mirror assembly 150 is used to change the first optical path direction A of the first polarized infrared laser and the second optical path direction B of the second polarized infrared laser respectively, so that the first polarized infrared laser and the second polarized infrared laser are respectively incident on the frequency-doubling element 140 from opposite sides of the frequency-doubling element 140.

[0060] The frequency doubling element 140 is configured to convert at least part of the first polarized infrared laser into a first green laser, and convert at least part of the second polarized infrared laser into a second green laser, and output the first green laser and the second green laser through the mirror assembly 150.

[0061] Wherein, the frequency doubling element 140 may specifically be a frequency doubling crystal.

[0062] In practical applications, it is mostly difficult for the frequency doubling element 140 to convert all the received non-polarization-maintaining infrared laser into a green laser. Therefore, for each received polarized infrared laser, the frequency doubling element 140 converts a part of the polarized infrared laser into a green laser and outputs it, and outputs the other part of the remaining polarized infrared laser that is not converted into a green laser.

[0063] The mirror assembly 150 is further configured to transmit the first path of remaining polarized infrared laser and the second path of remaining polarized infrared laser respectively output from the opposite two surfaces of the frequency doubling element 140 to the polarization beam splitter 130 and output them through the polarization beam splitter 130.

[0064] In some possible implementation manners, the mirror assembly 150 includes a first mirror assembly 151 and a second mirror assembly 152.

[0065] The first mirror assembly 151 is configured to change the second polarized infrared laser from the second optical path direction B to the fifth optical path direction E, so that the second polarized infrared laser enters the frequency doubling element 140 from the first surface 140a of the frequency doubling element 140 along the fifth optical path direction E; the fifth optical path direction E is parallel and in the same direction as the first optical path direction A.

[0066] The second mirror assembly 152 is configured to change the first polarized infrared laser from the first optical path direction A to the sixth optical path direction F, so that the first polarized infrared laser enters the frequency doubling element 140 from the second surface 140b opposite to the first surface 140a of the frequency doubling element 140 along the sixth optical path direction F; the sixth optical path direction F is parallel and in the opposite direction to the first optical path direction A.

[0067] Wherein, the fifth optical path direction E and the sixth optical path direction F are in opposite directions, and the transmission optical paths corresponding to them coincide.

[0068] Correspondingly, the frequency doubling element 140 is configured to convert at least part of the second polarized infrared laser received from the first surface 140a into a second green laser, and convert at least part of the first polarized infrared laser received from the second surface 140b into a first green laser.

[0069] Here, during the conversion process of the green laser by the frequency doubling element 140, heat generated by the absorbed and dissipated light will be absorbed. If too much heat is absorbed, in order to ensure the processing effect of the frequency doubling element 140, heat dissipation treatment needs to be performed on the frequency doubling element 140. Therefore, a temperature control element can be provided at the frequency doubling element 140 to cool the frequency doubling element 140 when the temperature of the frequency doubling element 140 is higher than a preset temperature threshold.

[0070] In some possible embodiments, the first polarized infrared laser is a parallel polarized light, and the second polarized infrared laser is a perpendicular polarized light. The parallel polarized light (p light) refers to light whose polarization direction is parallel to the optical path plane, and the perpendicular polarized light (s light) refers to light whose polarization direction is perpendicular to the optical path plane. The optical path plane is a plane used to describe the propagation of light.

[0071] In practical applications, the frequency doubling element 140 can only process light with a fixed polarization degree, and the polarization directions of the first polarized infrared laser and the second polarized infrared laser are different. In order to ensure that both the first polarized infrared laser and the second polarized infrared laser can be processed by the frequency doubling element 140, in the embodiments of the present disclosure, the polarization directions of the two polarized infrared lasers are respectively converted through two wave plates.

[0072] Specifically, the first mirror assembly 151 includes a first wave plate 1511, and the second mirror assembly 152 includes a second wave plate 1521.

[0073] The first wave plate 1511 is disposed on the fifth optical path direction E and near the first surface 140a, and is used to rotate the polarization direction of the second polarized infrared laser to a target polarization direction.

[0074] The second wave plate 1521 is disposed on the first optical path direction A and on the side of the polarization beam splitter 130 away from the resonant cavity assembly 120, and is used to rotate the polarization direction of the first polarized infrared laser to the target polarization direction.

[0075] Among them, the rotation direction of the first wave plate 1511 is opposite to the rotation direction of the second wave plate 1521, and the rotation angle of the first wave plate 1511 and the rotation angle of the second wave plate 1521 are 45 degrees.

[0076] Here, the target polarization direction is the polarization direction that the frequency doubling element 140 can process. The rotation direction of the first wave plate 1511 can be clockwise or counterclockwise. It can be understood that since the deviation angle between the p-polarized light and the s-polarized light is 90 degrees, the polarization direction of the p-polarized light after rotating 45 degrees clockwise is the same as the polarization direction of the s-polarized light after rotating 45 degrees counterclockwise. Similarly, the polarization direction of the p-polarized light after rotating 45 degrees counterclockwise is the same as the polarization direction of the s-polarized light after rotating 45 degrees clockwise. That is, the polarization state of the target polarization direction is between the p-polarized light and the s-polarized light.

[0077] Here, the first wave plate 1511 and the second wave plate 1521 can specifically be half-wave plates.

[0078] In order to inject the first polarized infrared laser and the second polarized infrared laser into the frequency doubling element 140, specifically, the first mirror assembly 151 further includes a first mirror 1512 and a first dichroic mirror 1513, and the second mirror assembly 152 further includes a second mirror 1522 and a second dichroic mirror 1523.

[0079] The first mirror 1512 is disposed on the fifth optical path direction E and on the side of the first wave plate 1511 away from the frequency doubling element 140, and is used to change the second polarized infrared laser from the second optical path direction B to the fifth optical path direction E.

[0080] The first dichroic mirror 1513 is disposed on the fifth optical path direction E and between the first wave plate 1511 and the frequency doubling element 140, and is used to transmit infrared laser and reflect green laser.

[0081] The second mirror 1522 is disposed on the first optical path direction A and on the side of the second wave plate 1521 away from the polarization beam splitter 130, and is used to change the first polarized infrared laser from the first optical path direction A to the seventh optical path direction G; the seventh optical path direction G is perpendicular to the first optical path direction A, and the seventh optical path direction G is parallel and in the same direction as the second optical path direction B.

[0082] The second dichroic mirror 1523 is disposed on the sixth optical path direction F and near the second surface 140b, and is used to reflect infrared laser and transmit green laser.

[0083] In some possible embodiments, the mirror assembly 150 is configured to convert the first residual polarized infrared laser beam and the second residual polarized infrared laser beam respectively output from two opposite surfaces of the frequency doubling element 140 into a third optical path direction C and a fourth optical path direction D, so that the first residual polarized infrared laser beam is incident on the polarization beam splitter 130 along the third optical path direction C and output by the polarization beam splitter 130, and the second residual polarized infrared laser beam is incident on the polarization beam splitter 130 along the fourth optical path direction D and output by the polarization beam splitter 130.

[0084] Wherein, the third optical path direction C is opposite to the second optical path direction B, and their corresponding transmission optical paths coincide; the fourth optical path direction D is opposite to the first optical path direction A, and their corresponding transmission optical paths coincide.

[0085] Here, the polarization beam splitter 130 is configured to output the first residual polarized infrared laser beam and the second residual polarized infrared laser beam respectively, or the polarization beam splitter 130 is configured to combine the first residual polarized infrared laser beam and the second residual polarized infrared laser beam into a residual non-polarization-maintaining infrared laser beam and then output it.

[0086] Specifically, the first mirror assembly 151 is configured to change the first residual polarized infrared laser beam output from the first surface 140a of the frequency doubling element 140 from a sixth optical path direction F to the third optical path direction C, so that the first residual polarized infrared laser beam is incident on the polarization beam splitter 130 along the third optical path direction C and output by the polarization beam splitter 130.

[0087] The second mirror assembly 152 is configured to change the second residual polarized infrared laser beam output from the second surface 140b of the frequency doubling element 140 from a fifth optical path direction E to the fourth optical path direction D, so that the second residual polarized infrared laser beam is incident on the polarization beam splitter 130 along the fourth optical path direction D and output by the polarization beam splitter 130.

[0088] Correspondingly, the first residual polarized infrared laser output from the first surface 140a passes through the first dichroic mirror 1513, and the polarization direction is rotated by the first waveplate 1511. The first residual polarized infrared laser after the polarization direction is rotated is parallel polarized light. The first residual polarized infrared laser after the polarization direction is rotated is reflected by the first mirror 1512 to the polarization beam splitter 130 for output; the second residual polarized infrared laser output from the second surface 140b is reflected by the second dichroic mirror 1523 and the second mirror 1522, and the polarization direction is rotated by the second waveplate 1521. The second residual polarized infrared laser after the polarization direction is rotated is perpendicular polarized light. The second residual polarized infrared laser after the polarization direction is rotated is output by the polarization beam splitter 130.

[0089] In some possible embodiments, the laser 100 further includes:

[0090] A third waveplate 160, disposed on the transmission optical path of the non-polarization-maintaining infrared laser and between the polarization beam splitter 130 and the resonant cavity assembly 120, for adjusting the ratio of splitting the first polarized infrared laser and the second polarized infrared laser.

[0091] Here, the third waveplate 160 may specifically be a half-wave plate.

[0092] In practical applications, a first optical power meter may be disposed on the first optical path direction A and between the polarization beam splitter 130 and the second waveplate 1521 for measuring the power of the first polarized infrared laser, and a second optical power meter may be disposed on the second optical path direction B and between the polarization beam splitter 130 and the first mirror 1512 for measuring the power of the second polarized infrared laser. According to the power of the first polarized infrared laser and the power of the second polarized infrared laser, the ratio of splitting the first polarized infrared laser and the second polarized infrared laser is determined.

[0093] By rotating the third waveplate 160, the polarization state of the incident non-polarization-maintaining infrared laser can be adjusted, thereby adjusting the ratio of splitting the first polarized infrared laser and the second polarized infrared laser.

[0094] In some possible embodiments, the resonant cavity assembly 120 includes a first grating 121, a gain fiber 122, and a second grating 123.

[0095] The first grating 121, as the first end of the resonant cavity, is used for receiving the pump light generated by the light source 110.

[0096] Among them, an optical path is transmitted between the light source 110 and the first grating 121 through an optical fiber.

[0097] The gain fiber 122 is disposed on a side of the first grating 121 away from the light source 110, and is configured to convert the pump light into non-polarization-maintaining infrared laser light.

[0098] Here, the gain fiber 122 performs an oscillation amplification process on the passing light source.

[0099] Among them, an optical path is transmitted between the first grating 121 and the gain fiber 122 through an optical fiber.

[0100] The second grating 123 is disposed on a side of the gain fiber 122 away from the first grating 121, and serves as the second end of the resonant cavity, and is configured to output the non-polarization-maintaining infrared laser light.

[0101] Among them, an optical path is transmitted between the gain fiber 122 and the second grating 123 through an optical fiber.

[0102] Here, in order to construct a resonant cavity, the reflectivity of the first grating 121 is greater than a preset reflectivity threshold, the reflectivity of the second grating 123 is less than the preset reflectivity threshold, and the preset reflectivity threshold can be determined according to actual laser generation requirements.

[0103] In order to improve the optical path transmission effect, in some possible embodiments, the laser 100 further includes:

[0104] A first lens 171 is disposed between the first dichroic mirror 1513 and the frequency doubling element 140, and is configured to collimate the light beam transmitted between the first dichroic mirror 1513 and the frequency doubling element 140; and / or

[0105] A second lens 172 is disposed between the frequency doubling element 140 and the second dichroic mirror 1523, and is configured to collimate the light beam transmitted between the frequency doubling element 140 and the second dichroic mirror 1523.

[0106] Here, the frequency doubling element 140 may be specifically located at the focal positions of the first lens 171 and the second lens 172. Since the first dichroic mirror 1513 and the second dichroic mirror 1523 can reflect the light beam, the first focal point and the second focal point of the first lens 171 are at the same position, and the first focal point and the second focal point of the second lens 172 are at the same position.

[0107] In order to protect the resonant cavity from being isolated from the outside and improve the generation effect of green laser light and infrared laser light, in some possible embodiments, the laser 100 further includes:

[0108] The first window mirror 181 is disposed on a side of the second dichroic mirror 1523 away from the frequency doubling element 140 for outputting the green laser light output by the second dichroic mirror 1523; and / or

[0109] The second window mirror 182 is disposed on a side of the polarization beam splitter 130 away from the first mirror 1512 for outputting the infrared laser light output by the polarization beam splitter 130.

[0110] Optionally, the laser 100 further includes:

[0111] A laser output head 191 is disposed between the resonator assembly 120 and the third wave plate 160 for collimating and emitting the non-polarization-maintaining infrared laser light output by the resonator assembly 120 to the third wave plate 160.

[0112] Wherein, an optical path is transmitted between the resonator assembly 120 and the laser output head 191 through an optical fiber.

[0113] In practical applications, the laser output head 191 may specifically be a Quick-Bayonet Housing (QBH) of a fiber laser.

[0114] In this way, since the light output by the resonator assembly 120 is relatively divergent and it is difficult to conduct the optical path to the third wave plate 160, by providing the laser output head 191 with a collimating and focusing function between the resonator assembly 120 and the third wave plate 160, the stable transmission of the optical path between the resonator assembly 120 and the third wave plate 160 can be ensured.

[0115] Optionally, a lens may be used to replace the laser output head 191 and be disposed between the resonator assembly 120 and the third wave plate 160, which can also play a role of collimation and focusing.

[0116] In practical applications, the light source 110 may be one or more. When there are multiple light sources 110, the laser 100 further includes:

[0117] A beam combiner 192 is disposed between the light source 110 and the resonator assembly 120 for combining and introducing the pump light generated by the multiple light sources 110 into the resonator.

[0118] Wherein, an optical path is transmitted between the light source 110, the beam combiner 192 and the resonator assembly 120 through an optical fiber.

[0119] In some possible embodiments, the extracavity frequency-doubled continuous green laser can be assembled on an optical platform for laser processing, such as metal welding, metal printing, etc., using the generated green laser.

[0120] To clearly show the working process of the extracavity frequency-doubled continuous green laser, reference can be made simultaneously to Figure 2 , and this example is described by taking a setup with multiple light sources as an example. As shown in Figure 2 , multiple light sources 110 respectively generate pump light. After the generated pump light is transmitted through an optical fiber to a beam combiner 192 for beam combination, it is introduced into a first grating 121 through an optical fiber, that is, introduced into the resonator.

[0121] The pump light is transmitted to a gain fiber 122 through the first grating 121, and the pump light is converted into non-polarization-maintaining infrared laser through the gain fiber 122. After the non-polarization-maintaining infrared laser outputs from the resonator through the second grating 123, it is transmitted to a laser output head 191 through an optical fiber. The non-polarization-maintaining infrared laser is collimated through the laser output head 191 and then emitted to a third wave plate 160. Through the third wave plate 160, after adjusting the polarization state of the non-polarization-maintaining infrared laser, it is emitted to a polarization beam splitter 130 to adjust the splitting ratio of the first-path polarized infrared laser and the second-path polarized infrared laser.

[0122] The non-polarization-maintaining infrared laser is split by the polarization beam splitter 130 into a first-path polarized infrared laser and a second-path polarized infrared laser that are transmitted along a first optical path direction A and a second optical path direction B respectively. Among them, the first optical path direction A is the same as the optical path direction of the non-polarization-maintaining infrared laser, and the second optical path direction B is perpendicular to the optical path direction of the non-polarization-maintaining infrared laser; the first-path polarized infrared laser is parallel polarized light, and the second-path polarized infrared laser is perpendicular polarized light.

[0123] The second-path polarized infrared laser is reflected by a first mirror 1512, changes from the second optical path direction B to a fifth optical path direction E, and rotates the polarization direction to a target polarization direction through a first wave plate 1511. The second-path polarized infrared laser with the converted polarization direction passes through a first dichroic mirror 1513, is collimated by a first lens 171, and then enters the frequency-doubling element 140 from the first surface 140a of the frequency-doubling element 140 along the fifth optical path direction E.

[0124] The first polarized infrared laser rotates its polarization direction to the target polarization direction through the second wave plate 1521. That is, the polarization direction of the first polarized infrared laser after converting the polarization direction is the same as that of the second polarized infrared laser after converting the polarization direction, both being the target polarization direction. The first polarized infrared laser after converting the polarization direction is reflected by the second mirror 1522, changing from the first optical path direction A to the seventh optical path direction G, and then reflected by the second dichroic mirror 1523, changing from the seventh optical path direction G to the sixth optical path direction F. After being collimated by the second lens 172, it enters the frequency doubling element 140 from the second surface 140b of the frequency doubling element 140 along the sixth optical path direction F.

[0125] The second green laser light converted from at least part of the first polarized infrared laser and output from the second surface 140b is emitted along the fifth optical path direction E to the second lens 172. After being collimated by the second lens 172, it passes through the second dichroic mirror 1523 and is output through the first window mirror 181.

[0126] The first green laser light converted from at least part of the first polarized infrared laser and output from the first surface 140a is emitted along the sixth optical path direction F to the first lens 171. After being collimated by the first lens 171, it is transmitted to the first dichroic mirror 1513. After being reflected by the first dichroic mirror 1513, it changes from the sixth optical path direction F to the fifth optical path direction E. After being collimated by the first lens 171, it enters the frequency doubling element 140 from the first surface 140a along the fifth optical path direction E, and then is output from the second surface 140b, emitted along the fifth optical path direction E to the second lens 172. After being collimated by the second lens 172, it passes through the second dichroic mirror 1523 and is output through the first window mirror 181.

[0127] The first residual polarized infrared laser output from the first surface 140a is emitted along the sixth optical path direction F to the first lens 171. After being collimated by the first lens 171, it passes through the first dichroic mirror 1513 and is transmitted to the first wave plate 1511. The polarization direction is rotated by the first wave plate 1511, and the first residual polarized infrared laser after converting the polarization direction becomes parallel polarized light again. The first residual polarized infrared laser after converting the polarization direction is reflected by the first mirror 1512, changing from the sixth optical path direction F to the third optical path direction C, and enters the polarization beam splitter 130 along the third optical path direction C, and is output through the second window mirror 182.

[0128] The second residual polarized infrared laser output from the second surface 140b is emitted along the fifth optical path direction E to the second lens 172, and after being collimated by the second lens 172, it is transmitted to the second dichroic mirror 1523. Then, after being reflected by the second dichroic mirror 1523, the direction is changed from the fifth optical path direction E to the eighth optical path direction H. Among them, the eighth optical path direction H is perpendicular to the first optical path direction A, and the eighth optical path direction H is parallel and in the same direction as the third optical path direction C. That is to say, the eighth optical path direction H is opposite to the seventh optical path direction G, and the transmission optical paths corresponding to the two coincide. Then, after being reflected by the second mirror 1522, the direction is changed from the eighth optical path direction H to the fourth optical path direction D, and it is transmitted along the fourth optical path direction D to the second wave plate 1521. The polarization direction is rotated by the second wave plate 1521, and the second residual polarized infrared laser after the polarization direction conversion becomes vertically polarized light again. The second residual polarized infrared laser after the polarization direction conversion is incident into the polarization beam splitter 130 along the fourth optical path direction D and is output through the second window mirror 182.

[0129] The extracavity frequency-doubled continuous green laser provided by the embodiments of the present disclosure adopts an extracavity frequency-doubling design. Since the frequency-doubling element is located outside the resonant cavity, compared with intracavity frequency doubling, it is less affected by the thermal effect and has less optical energy loss, which is beneficial to improving the frequency-doubling efficiency and beam quality of the green laser. At the same time, there is no need for precise alignment and coupling, effectively improving the stability of green laser generation, avoiding damage to the laser caused by coupling offset, and helping to improve the safety of green laser generation.

[0130] Those skilled in the art can understand that in the above method of the specific embodiment, the writing order of each step does not mean a strict execution order that constitutes any limitation to the implementation process, and the specific execution order of each step should be determined by its function and possible internal logic.

[0131] The above-described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the embodiments of the present invention without creative efforts fall within the scope of protection of the embodiments of the present invention.

[0132] In the description of the embodiments of the present disclosure, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the disclosed product is usually placed during use. It is only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the extracavity frequency-doubled continuous green laser or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present disclosure. In addition, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0133] In the description of the embodiments of the present disclosure, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "couple" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific situations.

[0134] Finally, it should be noted that the above-described embodiments are only specific implementation manners of the present disclosure, used to illustrate the technical solutions of the present disclosure, rather than limiting them. The protection scope of the present disclosure is not limited thereto. Although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present disclosure can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should all be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. An extracavity frequency-doubled continuous green laser, characterized in that, It includes a light source for generating pump light, a resonant cavity component, a polarization beam splitter, a frequency doubling element, and a mirror component; The resonant cavity component is used to receive the pump light generated by the light source and convert the pump light into non-polarization-maintaining infrared laser; The polarization beam splitter is arranged on the transmission optical path of the non-polarization-maintaining infrared laser and is used to split the non-polarization-maintaining infrared laser into a first polarized infrared laser and a second polarized infrared laser that are respectively transmitted along a first optical path direction and a second optical path direction; the polarization directions of the first polarized infrared laser and the second polarized infrared laser are different; the first optical path direction is the same as the optical path direction of the non-polarization-maintaining infrared laser, and the second optical path direction is perpendicular to the optical path direction of the non-polarization-maintaining infrared laser; The mirror component is used to respectively change the first optical path direction of the first polarized infrared laser and the second optical path direction of the second polarized infrared laser, so that the first polarized infrared laser and the second polarized infrared laser respectively enter the frequency doubling element from two opposite sides of the frequency doubling element; The frequency doubling element is used to convert at least part of the first polarized infrared laser into a first green laser and convert at least part of the second polarized infrared laser into a second green laser, and output the first green laser and the second green laser through the mirror component; The mirror component is further used to transmit the first residual polarized infrared laser and the second residual polarized infrared laser respectively output from two opposite sides of the frequency doubling element to the polarization beam splitter and output them through the polarization beam splitter.

2. The laser according to claim 1, wherein The mirror component is used to convert the first residual polarized infrared laser and the second residual polarized infrared laser respectively output from two opposite sides of the frequency doubling element into a third optical path direction and a fourth optical path direction, so that the first residual polarized infrared laser enters the polarization beam splitter along the third optical path direction and is output through the polarization beam splitter, and the second residual polarized infrared laser enters the polarization beam splitter along the fourth optical path direction and is output through the polarization beam splitter; the third optical path direction is opposite to the second optical path direction, and the fourth optical path direction is opposite to the first optical path direction.

3. The laser according to claim 1, wherein The mirror component includes a first mirror component and a second mirror component; The first mirror component is used to change the second polarized infrared laser from the second optical path direction to a fifth optical path direction, so that the second polarized infrared laser enters the frequency doubling element from the first side of the frequency doubling element along the fifth optical path direction; the fifth optical path direction is parallel and in the same direction as the first optical path direction; The second mirror component is used to change the first polarized infrared laser from the first optical path direction to a sixth optical path direction, so that the first polarized infrared laser enters the frequency doubling element from the second side opposite to the first side of the frequency doubling element along the sixth optical path direction; the sixth optical path direction is parallel and in the opposite direction to the first optical path direction.

4. The laser according to claim 3, characterized in that, The first polarized infrared laser is a parallel polarized light, and the second polarized infrared laser is a perpendicular polarized light; the first mirror assembly includes a first wave plate, and the second mirror assembly includes a second wave plate; The first wave plate is arranged in the fifth optical path direction and close to the first surface, and is used to rotate the polarization direction of the second polarized infrared laser to a target polarization direction; The second wave plate is arranged in the first optical path direction and on the side of the polarization beam splitter away from the resonant cavity assembly, and is used to rotate the polarization direction of the first polarized infrared laser to the target polarization direction; The rotation direction of the first wave plate is opposite to that of the second wave plate, and the rotation angle of the first wave plate and the rotation angle of the second wave plate are 45 degrees.

5. The laser according to claim 2, characterized in that, The mirror assembly includes a first mirror assembly and a second mirror assembly; The first mirror assembly is used to change the first residual polarized infrared laser output from the first surface of the frequency doubling element from the sixth optical path direction to the third optical path direction, so that the first residual polarized infrared laser is incident on the polarization beam splitter along the third optical path direction and is output through the polarization beam splitter; The second mirror assembly is used to change the second residual polarized infrared laser output from the second surface of the frequency doubling element from the fifth optical path direction to the fourth optical path direction, so that the second residual polarized infrared laser is incident on the polarization beam splitter along the fourth optical path direction and is output through the polarization beam splitter.

6. The laser according to claim 4, characterized in that, The first mirror assembly further includes a first mirror and a first dichroic mirror, and the second mirror assembly further includes a second mirror and a second dichroic mirror; The first mirror is arranged in the fifth optical path direction and on the side of the first wave plate away from the frequency doubling element, and is used to change the second polarized infrared laser from the second optical path direction to the fifth optical path direction; The first dichroic mirror is arranged in the fifth optical path direction and between the first wave plate and the frequency doubling element, and is used to transmit infrared laser and reflect green laser; The second mirror is arranged in the first optical path direction and on the side of the second wave plate away from the polarization beam splitter, and is used to change the first polarized infrared laser from the first optical path direction to the seventh optical path direction; the seventh optical path direction is perpendicular to the first optical path direction, and the seventh optical path direction is parallel and in the same direction as the second optical path direction; The second dichroic mirror is arranged in the sixth optical path direction and close to the second surface, and is used to reflect infrared laser and transmit green laser.

7. The laser according to claim 1, characterized in that, The laser further includes: A third wave plate is arranged on the transmission optical path of the non-polarization-maintaining infrared laser and between the polarization beam splitter and the resonant cavity assembly, and is used to adjust the ratio of splitting the first polarized infrared laser and the second polarized infrared laser.

8. The laser according to claim 1, characterized in that, The resonant cavity assembly includes a first grating, a gain fiber, and a second grating; The first grating, as the first end of the resonant cavity, is used to receive the pump light generated by the light source; The gain fiber is disposed on a side of the first grating away from the light source and is configured to convert the pump light into non-polarization-maintaining infrared laser light; The second grating is disposed on a side of the gain fiber away from the first grating and serves as a second end of the resonant cavity for outputting the non-polarization-maintaining infrared laser light.

9. The laser according to claim 6, characterized in that, The laser further includes: A first lens disposed between the first dichroic mirror and the frequency doubling element for collimating the light beam transmitted between the first dichroic mirror and the frequency doubling element; and / or A second lens disposed between the frequency doubling element and the second dichroic mirror for collimating the light beam transmitted between the frequency doubling element and the second dichroic mirror.

10. The laser according to claim 6, characterized in that, The laser further includes: A first window mirror disposed on a side of the second dichroic mirror away from the frequency doubling element for outputting the green laser light output by the second dichroic mirror; and / or A second window mirror disposed on a side of the polarization beam splitter away from the first mirror for outputting the infrared laser light output by the polarization beam splitter.

Images