Outside-cavity frequency doubling continuous green laser
By using external cavity frequency doubling design and polarization beam splitter, the problems of low frequency doubling efficiency and poor stability of non-polarization-maintaining infrared lasers were solved, achieving efficient and stable generation of green lasers and improved safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2026-04-03
AI Technical Summary
In the existing technology, although non-polarization-maintaining infrared lasers reduce costs when used as frequency doubling sources for green lasers, they have low frequency doubling efficiency, poor stability and safety, and are particularly susceptible to thermal effects during intracavity frequency doubling, which can easily lead to laser damage.
An external frequency doubling design is adopted, which uses a polarization beam splitter to split the non-polarization-maintaining infrared laser into two lasers with different polarization directions. These lasers are then incident on the frequency doubling element through a mirror assembly and converted into green laser light. The polarization direction is adjusted by a waveplate to adapt to the processing of the frequency doubling element, thereby reducing heat effects and light energy loss.
This improves the frequency doubling efficiency and stability of green lasers, reduces light energy loss, avoids laser damage caused by coupling misalignment, and enhances generation safety.
Smart Images
Figure CN224082912U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of laser technology, and more specifically, to an extracavity frequency-doubled continuous green laser. Background Technology
[0002] Continuous green lasers have attracted much attention due to their wide application in metal welding, metal printing, and other fields. To reduce costs, non-polarization-maintaining infrared lasers are typically used as the frequency doubling source for generating green laser light. However, while this method reduces costs, it results in low frequency doubling efficiency, poor stability, and poor safety. Therefore, ensuring the frequency doubling efficiency, stability, and safety of green lasers has become an urgent problem to be solved. Utility Model Content
[0003] This utility model provides at least one extracavity frequency-doubled continuous green laser, which can not only improve the frequency doubling efficiency of green laser, but also improve the stability and safety of green laser generation.
[0004] This utility model provides 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 used 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 used to split the non-polarization-maintaining infrared laser into a first polarized infrared laser and a second polarized infrared laser that are transmitted along a first optical path direction and a second optical path direction, respectively; 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 reflector assembly is used to change the first optical path direction of the first polarized infrared laser and the second optical path direction of the second polarized infrared laser respectively, 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 used to convert at least a portion of the first polarized infrared laser into a first green laser, and at least a portion of the second polarized infrared laser into a second green laser, and output the first green laser and the second green laser through the reflector assembly;
[0009] The mirror assembly is also used to transmit the first residual polarized infrared laser and the second residual polarized infrared laser, which are respectively output from the two opposite sides of the frequency doubling element, to the polarization beam splitter and output through the polarization beam splitter.
[0010] In one optional embodiment, the reflector assembly is used to convert the first residual polarized infrared laser and the second residual polarized infrared laser output from opposite sides of the frequency doubling element into a third optical path direction and a fourth optical path direction, respectively, such 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.
[0011] In one optional embodiment, the reflector assembly includes a first reflector assembly and a second reflector assembly;
[0012] The first reflector assembly is used to change the second polarized infrared laser from the second optical path direction to the fifth optical path direction, so that the second polarized infrared laser enters the frequency doubling element from the first surface of the frequency doubling element along the fifth optical path direction; the fifth optical path direction is parallel to and has the same direction as the first optical path direction;
[0013] The second reflector assembly is used to change the first polarized infrared laser from the first optical path direction to the sixth optical path direction, so that the first polarized infrared laser enters the frequency doubling element from the second surface opposite to the first surface along the sixth optical path direction; the sixth optical path direction is parallel to and opposite to the first optical path direction.
[0014] In one optional embodiment, the first polarized infrared laser is parallel polarized light, and the second polarized infrared laser is vertical polarized light; the first reflector assembly includes a first waveplate, and the second reflector assembly includes a second waveplate.
[0015] The first waveplate is disposed 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 the target polarization direction;
[0016] The second waveplate is disposed in the first optical path direction and is located on the side of the polarization beam splitter away from the resonant cavity assembly, for rotating the polarization direction of the first polarized infrared laser to the target polarization direction;
[0017] The rotation direction of the first waveplate is opposite to that of the second waveplate, and the rotation angle of the first waveplate is 45 degrees to that of the second waveplate.
[0018] In one optional embodiment, the reflector assembly includes a first reflector assembly and a second reflector assembly;
[0019] The first reflector 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 enters the polarization beam splitter along the third optical path direction and is output through the polarization beam splitter.
[0020] The second reflector assembly is used to change the direction of the second residual polarized infrared laser output from the second surface of the frequency doubling element from the fifth optical path to the fourth optical path, so that the second residual polarized infrared laser enters the polarization beam splitter along the fourth optical path and is output through the polarization beam splitter.
[0021] In one optional embodiment, the first reflector assembly further includes a first reflector and a first dichroic mirror, and the second reflector assembly further includes a second reflector and a second dichroic mirror;
[0022] The first reflector is disposed in the fifth optical path direction and is located on the side of the first waveplate 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;
[0023] The first dichroic mirror is disposed in the fifth optical path direction and located between the first waveplate and the frequency doubling element, for transmitting infrared laser and reflecting green laser;
[0024] The second reflector is disposed in the first optical path direction and located on the side of the second waveplate 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 parallel to the second optical path direction and has the same direction.
[0025] The second dichroic mirror is positioned in the sixth optical path direction and close to the second surface, and is used to reflect infrared laser light and transmit green laser light.
[0026] In one optional implementation, the laser further includes:
[0027] The third waveplate 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, for adjusting the ratio of splitting the first polarization infrared laser and the second polarization infrared laser.
[0028] In one optional embodiment, the resonant cavity assembly includes a first grating, a gain fiber, and a second grating;
[0029] The first grating, serving 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 the side of the first grating away from the light source, and is used to convert the pump light into non-polarization-maintaining infrared laser.
[0031] The second grating is disposed on the side of the gain fiber away from the first grating, serving as the second end of the resonant cavity, and is used to output the non-polarization-maintaining infrared laser.
[0032] In one optional implementation, the laser further includes:
[0033] A first lens, disposed between the first dichroic mirror and the frequency doubling element, 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 one optional implementation, the laser further includes:
[0036] A first window mirror, disposed on the side of the second dichroic mirror away from the frequency doubling element, is used to output the green laser light emitted by the second dichroic mirror; and / or
[0037] The second window mirror is disposed on the side of the polarization beam splitter away from the first reflector, and is used to output the infrared laser output by the polarization beam splitter.
[0038] The external frequency-doubled continuous green laser provided in this embodiment adopts an external frequency-doubled design. Since the frequency-doubled element is located outside the resonant cavity, it is less affected by thermal effects compared with intracavity frequency doubling, resulting in less energy loss of light. This is beneficial to improving the frequency doubling efficiency and beam quality of the green laser. At the same time, it eliminates the need for precise alignment and coupling, effectively improving the stability of green laser generation and avoiding laser damage caused by coupling misalignment, thus helping to improve the safety of green laser generation.
[0039] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this utility model.
[0040] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0041] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to this utility model and, together with the specification, serve to explain the technical solutions of this utility model. It should be understood that the following drawings only show some embodiments of this utility model and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0042] Figure 1 This diagram illustrates the principle block diagram of an extracavity frequency-doubled continuous green laser provided in an embodiment of the present invention.
[0043] Figure 2 A schematic diagram of an extracavity frequency-doubled continuous green laser provided in an embodiment of the present invention is shown. Detailed Implementation
[0044] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely represents selected embodiments of the utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.
[0045] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0046] In this document, the term "and / or" merely describes a relationship, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.
[0047] Furthermore, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein.
[0048] Research has shown that to reduce the cost of generating green light, non-polarization-maintaining infrared lasers are typically used as the frequency-doubling source, employing intracavity frequency doubling. While this method reduces costs, it suffers from significant thermal effects and energy loss during intracavity frequency doubling, resulting in low frequency doubling efficiency. Furthermore, intracavity frequency doubling requires precise alignment and coupling, leading to poor stability. Additionally, if coupling misalignment occurs due to vibration or other factors, it can damage or even burn out the laser, compromising the safety of green light generation. Increasing coupling efficiency is complex and time-consuming. Therefore, ensuring the frequency doubling efficiency, stability, and safety of green lasers has become a pressing issue.
[0049] Based on the above research, this invention provides an externally frequency-doubled continuous green laser. By adopting an externally frequency-doubled design, since the frequency-doubled element is located outside the resonant cavity, it is less affected by thermal effects and has less light energy loss compared to intracavity frequency doubling. This is beneficial to improving the frequency doubling efficiency and beam quality of the green laser. At the same time, it eliminates the need for precise alignment and coupling, effectively improving the stability of green laser generation and avoiding laser damage caused by coupling misalignment, thus contributing to improved safety in green laser generation.
[0050] The following description, in conjunction with the accompanying drawings, illustrates an extracavity frequency-doubled continuous green laser according to an embodiment of the present invention.
[0051] Please see Figure 1 and Figure 2 , Figure 1 A schematic diagram of an extracavity frequency-doubled continuous green laser provided in an embodiment of this utility model. Figure 2 A schematic diagram of an extracavity frequency-doubled continuous green laser provided as an embodiment of this utility model. See also... Figure 1As shown, 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] The light source 110 and the resonant cavity assembly 120 are connected by an optical fiber for optical transmission.
[0055] This embodiment of the invention achieves the use of non-polarization-maintaining infrared laser as a frequency-doubled source for generating green laser by converting pump light into non-polarization-maintaining infrared laser. This eliminates the need for polarization-maintaining devices to generate polarization-maintaining infrared laser as a frequency-doubled source, reducing the difficulty and cost of generating a frequency-doubled 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, which are transmitted along a first optical path direction A and a second optical path direction B, respectively. 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 exceeds the preset heat threshold, the extinction degradation ratio problem is likely to occur. The linear polarization degree will degrade due to the high heat, resulting in a decrease in the effective power that can be used to generate green light by frequency doubling, which affects the output stability of green laser.
[0058] In this embodiment, the non-polarization-maintaining infrared laser is split into two polarized infrared lasers by a polarization beam splitter 130 for transmission, which avoids the extinction ratio degradation problem caused by high heat and improves the effective power of frequency doubling to generate green light and the output stability of green laser.
[0059] The reflector 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, so that the first polarized infrared laser and the second polarized infrared laser are respectively injected into the frequency doubling element 140 from opposite sides.
[0060] The frequency doubling element 140 is used to convert at least a portion of the first polarized infrared laser into a first green laser, and at least a portion of the second polarized infrared laser into a second green laser, and output the first green laser and the second green laser through the reflector assembly 150.
[0061] Specifically, the frequency doubling element 140 can be a frequency doubling crystal.
[0062] In practical applications, the frequency doubling element 140 often cannot convert all the received non-polarization-maintaining infrared lasers into green lasers. Therefore, for each received polarized infrared laser, the frequency doubling element 140 converts a portion of the polarized infrared laser into green laser and outputs the remaining portion of the polarized infrared laser that has not been converted into green laser.
[0063] The mirror assembly 150 is also used to transmit the first residual polarized infrared laser and the second residual polarized infrared laser, which are respectively output from the two opposite sides 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 implementations, the mirror assembly 150 includes a first mirror assembly 151 and a second mirror assembly 152.
[0065] The first reflector assembly 151 is used 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 along the fifth optical path direction E; the fifth optical path direction E is parallel to and has the same direction as the first optical path direction A.
[0066] The second reflector assembly 152 is used 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 along the sixth optical path direction F; the sixth optical path direction F is parallel to and opposite to the first optical path direction A.
[0067] The fifth optical path direction E and the sixth optical path direction F are opposite in direction, and their corresponding transmission optical paths coincide.
[0068] Accordingly, the frequency doubling element 140 is used to convert at least a portion of the second polarized infrared laser received from the first surface 140a into a second green laser, and to convert at least a portion of the first polarized infrared laser received from the second surface 140b into a first green laser.
[0069] Here, during the conversion of green laser light, the frequency multiplier 140 absorbs heat generated by the lost light. If excessive heat is absorbed, heat dissipation is required to ensure the processing effect of the frequency multiplier 140. Therefore, a temperature control element can be installed at the frequency multiplier 140 to cool it down when its temperature exceeds a preset temperature threshold.
[0070] In some possible implementations, the first polarized infrared laser is parallel polarized light, and the second polarized infrared laser is 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, where the optical path plane is a plane used to describe light propagation.
[0071] In practical applications, the frequency doubling element 140 can only process light with a fixed degree of polarization. However, 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, this embodiment of the invention uses two waveplates to convert the polarization directions of the two polarized infrared lasers.
[0072] Specifically, the first reflector assembly 151 includes a first wave plate 1511, and the second reflector assembly 152 includes a second wave plate 1521.
[0073] The first waveplate 1511 is disposed on the fifth optical path direction E and close to the first surface 140a, and is used to rotate the polarization direction of the second polarized infrared laser to the target polarization direction.
[0074] The second waveplate 1521 is disposed on the first optical path direction A and located 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] The first waveplate 1511 rotates in the opposite direction to the second waveplate 1521, and the rotation angle of the first waveplate 1511 is 45 degrees to that of the second waveplate 1521.
[0076] Here, the target polarization direction is the polarization direction that the frequency doubling element 140 can process. The rotation direction of the first waveplate 1511 is clockwise or counterclockwise. It can be understood that since the deviation angle between the p-light and the s-light is 90 degrees, the polarization direction of the p-light after rotating 45 degrees clockwise is the same as the polarization direction of the s-light after rotating 45 degrees counterclockwise. Similarly, the polarization direction of the p-light after rotating 45 degrees counterclockwise is the same as the polarization direction of the s-light after rotating 45 degrees clockwise. That is, the polarization state of the target polarization direction is between the p-light and the s-light.
[0077] Here, the first waveplate 1511 and the second waveplate 1521 can specifically be half-waveplates.
[0078] In order to enable the first polarized infrared laser and the second polarized infrared laser to be injected into the frequency doubling element 140, specifically, the first reflector assembly 151 further includes a first reflector 1512 and a first dichroic mirror 1513, and the second reflector assembly 152 further includes a second reflector 1522 and a second dichroic mirror 1523.
[0079] The first reflector 1512 is disposed on the fifth optical path direction E and is located on the side of the first waveplate 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 located between the first waveplate 1511 and the frequency doubling element 140, for transmitting infrared laser and reflecting green laser.
[0081] The second reflector 1522 is disposed on the first optical path direction A and located on the side of the second waveplate 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 to the second optical path direction B and has the same direction.
[0082] The second dichroic mirror 1523 is disposed on the sixth optical path direction F and close to the second surface 140b, and is used to reflect infrared laser and transmit green laser.
[0083] In some possible implementations, the mirror assembly 150 is used to convert the first residual polarized infrared laser and the second residual polarized infrared laser output from opposite sides of the frequency doubling element 140 into a third optical path direction C and a fourth optical path direction D, respectively, such that the first residual polarized infrared laser enters the polarization beam splitter 130 along the third optical path direction C and is output through the polarization beam splitter 130, and the second residual polarized infrared laser enters the polarization beam splitter 130 along the fourth optical path direction D and is output through the polarization beam splitter 130.
[0084] Wherein, the third optical path direction C is opposite to the second optical path direction B, and the corresponding transmission optical paths of the two coincide; the fourth optical path direction D is opposite to the first optical path direction A, and the corresponding transmission optical paths of the two coincide.
[0085] Here, the polarization beam splitter 130 is used to output the first residual polarized infrared laser and the second residual polarized infrared laser respectively, or the polarization beam splitter 130 is used to combine the first residual polarized infrared laser and the second residual polarized infrared laser into a residual non-polarization-maintaining infrared laser and then output it.
[0086] Specifically, the first reflector assembly 151 is used to change the first residual polarized infrared laser output from the first surface 140a of the frequency doubling element 140 from the sixth optical path direction F to the third optical path direction C, so that the first residual polarized infrared laser enters the polarization beam splitter 130 along the third optical path direction C and is output through the polarization beam splitter 130.
[0087] The second reflector assembly 152 is used to change the second residual polarized infrared laser output from the second surface 140b of the frequency doubling element 140 from the fifth optical path direction E to the fourth optical path direction D, so that the second residual polarized infrared laser enters the polarization beam splitter 130 along the fourth optical path direction D and is output through 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 is rotated in polarization direction by the first waveplate 1511. The first residual polarized infrared laser after polarization rotation is parallel polarized light. The first residual polarized infrared laser after polarization rotation is reflected by the first reflector 1512 and output by the polarization beam splitter 130. The second residual polarized infrared laser output from the second surface 140b is reflected by the second dichroic mirror 1523 and the second reflector 1522 and is rotated in polarization direction by the second waveplate 1521. The second residual polarized infrared laser after polarization rotation is vertically polarized light. The second residual polarized infrared laser after polarization rotation is output by the polarization beam splitter 130.
[0089] In some possible implementations, the laser 100 further includes:
[0090] The third waveplate 160 is disposed in the transmission optical path of the non-polarization-maintaining infrared laser and is located between the polarization beam splitter 130 and the resonant cavity assembly 120, and is used to adjust the ratio of splitting the first polarization infrared laser and the second polarization infrared laser.
[0091] Here, the third waveplate 160 can specifically be a half-waveplate.
[0092] In practical applications, a first optical power measuring instrument can be positioned along the first optical path direction A, between the polarization beam splitter 130 and the second waveplate 1521, to measure the power of the first polarized infrared laser. A second optical power measuring instrument can be positioned along the second optical path direction B, between the polarization beam splitter 130 and the first reflector 1512, to measure the power of the second polarized infrared laser. Based on the power of the first and second polarized infrared lasers, the ratio of splitting the first and second polarized infrared laser beams can be 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 the first polarized infrared laser and the second polarized infrared laser beam.
[0094] In some possible implementations, 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 to receive the pump light generated by the light source 110.
[0096] The light source 110 and the first grating 121 are connected by an optical fiber for optical path transmission.
[0097] The gain fiber 122 is disposed on the side of the first grating 121 away from the light source 110, and is used to convert the pump light into non-polarization-maintaining infrared laser.
[0098] Here, the gain fiber 122 performs oscillation amplification processing on all passing light sources.
[0099] The first grating 121 and the gain fiber 122 are connected by an optical fiber for optical path transmission.
[0100] The second grating 123 is disposed on the side of the gain fiber 122 away from the first grating 121, serving as the second end of the resonant cavity, and is used to output the non-polarization-maintaining infrared laser.
[0101] The gain fiber 122 and the second grating 123 are connected by an optical fiber for optical path transmission.
[0102] Here, in order to construct the resonant cavity, the reflectivity of the first grating 121 is greater than a preset reflectivity threshold, and the reflectivity of the second grating 123 is less than the preset reflectivity threshold. The preset reflectivity threshold can be determined according to the actual laser generation requirements.
[0103] To improve optical transmission performance, in some possible implementations, the laser 100 further includes:
[0104] A first lens 171 is disposed between the first dichroic mirror 1513 and the frequency doubling element 140, for collimating the light beam transmitted between the first dichroic mirror 1513 and the frequency doubling element 140; and / or
[0105] The second lens 172 is disposed between the frequency doubling element 140 and the second dichroic mirror 1523, and is used 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 can be located at the focal point of the first lens 171 and the second lens 172, because the first dichroic mirror 1513 and the second dichroic mirror 1523 can reflect the light beam. Therefore, 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] To protect the resonant cavity from the outside world and improve the generation effect of green and infrared lasers, in some possible embodiments, the laser 100 further includes:
[0108] A first window mirror 181 is disposed on the side of the second dichroic mirror 1523 away from the frequency doubling element 140, for outputting the green laser light emitted by the second dichroic mirror 1523; and / or
[0109] The second window mirror 182 is disposed on the side of the polarization beam splitter 130 away from the first reflector 1512, and is used to output the infrared laser output by the polarization beam splitter 130.
[0110] Optionally, the laser 100 further includes:
[0111] A laser output head 191 is disposed between the resonant cavity assembly 120 and the third waveplate 160, and is used to collimate the non-polarization-maintaining infrared laser output from the resonant cavity assembly 120 and then transmit it to the third waveplate 160.
[0112] The resonant cavity assembly 120 and the laser output head 191 are connected by an optical fiber for optical transmission.
[0113] In practical applications, the laser output head 191 can specifically be a quick-swap fiber laser output head (Quick-Bayonet Housing, QBH).
[0114] Thus, since the light output from the resonant cavity assembly 120 is relatively diffuse, it is difficult for the optical path to be guided to the third waveplate 160. By setting a laser output head 191 with collimation and focusing function between the resonant cavity assembly 120 and the third waveplate 160, the stable transmission of the optical path between the resonant cavity assembly 120 and the third waveplate 160 can be guaranteed.
[0115] Optionally, a lens can be used instead of the laser output head 191 and placed between the resonant cavity assembly 120 and the third waveplate 160, which can also achieve the function of collimation and focusing.
[0116] In practical applications, there can be one or more light sources 110. 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 resonant cavity assembly 120, and is used to combine the pump light beams generated by the multiple light sources 110 into the resonant cavity.
[0118] The light source 110, the beam combiner 192, and the resonant cavity assembly 120 are connected by optical fiber for optical path transmission.
[0119] In some possible implementations, the extracavity frequency-doubled continuous green laser can be mounted on an optical platform for laser processing using the generated green laser light, such as metal welding and metal printing.
[0120] To clearly demonstrate the operation of an extracavity frequency-doubled continuous-wave green laser, please refer to [the relevant documentation / reference]. Figure 2 This example illustrates the situation using a setup with multiple light sources, such as... Figure 2 As shown, multiple light sources 110 generate pump light respectively. The generated pump light is transmitted through optical fiber to the combiner 192 for beam combining, and then guided through optical fiber into the first grating 121, that is, into the resonant cavity.
[0121] The pump light is transmitted through the first grating 121 to the gain fiber 122, where it is converted into a non-polarization-maintaining infrared laser. The non-polarization-maintaining infrared laser passes through the second grating 123 and exits the resonant cavity, then is transmitted through the fiber to the laser output head 191. The laser output head 191 collimates the non-polarization-maintaining infrared laser and emits it to the third waveplate 160. The polarization state of the non-polarization-maintaining infrared laser is adjusted by the third waveplate 160 before it is emitted to the polarization beam splitter 130 to adjust the ratio of the first and second polarization-maintaining infrared laser beams.
[0122] The non-polarization-maintaining infrared laser is split into a first polarized infrared laser and a second polarized infrared laser, respectively, by the polarization beam splitter 130, which propagate along a first optical path direction A and a second optical path direction B. 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 polarized infrared laser is parallel polarized light, and the second polarized infrared laser is perpendicular polarized light.
[0123] The second polarized infrared laser is reflected by the first reflecting mirror 1512, changing from the second optical path direction B to the fifth optical path direction E. The polarization direction is then rotated to the target polarization direction by the first waveplate 1511. After the polarization direction is changed, the second polarized infrared laser passes through the first dichroic mirror 1513, is collimated by the first lens 171, and enters the frequency doubling element 140 from the first surface 140a along the fifth optical path direction E.
[0124] The first polarized infrared laser is rotated to the target polarization direction by the second waveplate 1521. That is, the polarization direction of the first polarized infrared laser after polarization conversion is the same as that of the second polarized infrared laser after polarization conversion, both being the target polarization direction. The first polarized infrared laser after polarization conversion is reflected by the second reflector 1522, changing from the first optical path direction A to the seventh optical path direction G. Then, it is 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 along the sixth optical path direction F.
[0125] The second green laser light output from the second surface 140b, which is converted from at least a portion of the first polarized infrared laser light, 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 a portion of the first polarized infrared laser light, 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 is then output from the second surface 140b. It 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.
[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 waveplate 1511. The polarization direction is rotated by the first waveplate 1511, and the first residual polarized infrared laser, after its polarization direction is changed, becomes parallel polarized light again. The first residual polarized infrared laser, after its polarization direction is changed, is reflected by the first reflector 1512, and changes from the sixth optical path direction F to the third optical path direction C. It then 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 reflection by the second dichroic mirror 1523, the fifth optical path direction E is changed to the eighth optical path direction H, wherein the eighth optical path direction H is perpendicular to the first optical path direction A, and parallel to and in the same direction as the third optical path direction C. That is, the eighth optical path direction H is opposite to the seventh optical path direction G, and their corresponding transmission paths coincide. Next, after reflection by the second reflector 1522, the eighth optical path direction H is changed to the fourth optical path direction D, and it is transmitted along the fourth optical path direction D to the second waveplate 1521. The second waveplate 1521 rotates the polarization direction, and the second residual polarized infrared laser, after its polarization direction change, becomes vertically polarized light again. The second residual polarized infrared laser, after polarization direction conversion, enters the polarization beam splitter 130 along the fourth optical path direction D and is output through the second window mirror 182.
[0129] The external frequency-doubled continuous green laser provided in this embodiment adopts an external frequency-doubled design. Since the frequency-doubled element is located outside the resonant cavity, it is less affected by thermal effects compared with intracavity frequency doubling, resulting in less energy loss of light. This is beneficial to improving the frequency doubling efficiency and beam quality of the green laser. At the same time, it eliminates the need for precise alignment and coupling, effectively improving the stability of green laser generation and avoiding laser damage caused by coupling misalignment, thus helping to improve the safety of green laser generation.
[0130] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.
[0131] The embodiments described above are some, but not all, embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the protection scope of this utility model.
[0132] In the description of the embodiments of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the extracavity frequency-doubled continuous green laser or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0133] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0134] Finally, it should be noted that the above-described embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model. These modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.
Claims
1. An extra-cavity frequency-doubled continuous-wave green laser, characterized in that, The light source is used for generating pump light, the resonant cavity assembly, the polarization beam splitter, the frequency doubling element and the mirror assembly; The resonant cavity assembly is used for receiving the pump light generated by the light source and converting the pump light into non-polarization maintaining infrared laser; The polarization beam splitter is arranged on the transmission path of the non-polarization maintaining infrared laser and is used for splitting the non-polarization maintaining infrared laser into first and second polarization maintaining infrared lasers which are transmitted along first and second light path directions respectively; the polarization directions of the first and second polarization maintaining infrared lasers are different; the first light path direction is the same as the light path direction of the non-polarization maintaining infrared laser, and the second light path direction is perpendicular to the light path direction of the non-polarization maintaining infrared laser; The mirror assembly is used for changing the first and second light path directions of the first and second polarization maintaining infrared lasers respectively, so that the first and second polarization maintaining infrared lasers are incident into the frequency doubling element from opposite sides of the frequency doubling element respectively; The frequency doubling element is used for converting at least part of the first polarization maintaining infrared laser into first green laser and at least part of the second polarization maintaining infrared laser into second green laser, and outputting the first and second green lasers through the mirror assembly; The mirror assembly is also used for transmitting first and second residual polarization maintaining infrared lasers output from opposite sides of the frequency doubling element to the polarization beam splitter and outputting the first and second residual polarization maintaining infrared lasers through the polarization beam splitter.
2. The laser of claim 1, wherein, The mirror assembly is used for converting the first and second residual polarization maintaining infrared lasers output from opposite sides of the frequency doubling element into third and fourth light path directions, so that the first residual polarization maintaining infrared laser is incident into the polarization beam splitter along the third light path direction and output through the polarization beam splitter, and the second residual polarization maintaining infrared laser is incident into the polarization beam splitter along the fourth light path direction and output through the polarization beam splitter; the third light path direction is opposite to the second light path direction, and the fourth light path direction is opposite to the first light path direction.
3. The laser of claim 1, wherein, The mirror assembly includes a first mirror assembly and a second mirror assembly; The first mirror assembly is used for changing the second polarization maintaining infrared laser from the second light path direction to a fifth light path direction, so that the second polarization maintaining infrared laser is incident into the frequency doubling element from a first side of the frequency doubling element along the fifth light path direction; the fifth light path direction is parallel to and the same as the first light path direction; The second mirror assembly is used for changing the first polarization maintaining infrared laser from the first light path direction to a sixth light path direction, so that the first polarization maintaining infrared laser is incident into the frequency doubling element from a second side of the frequency doubling element opposite to the first side along the sixth light path direction; the sixth light path direction is parallel to and opposite to the first light path direction.
4. The laser of claim 3, wherein, The first polarized infrared laser is parallel polarized light, and the second polarized infrared laser is vertical polarized light; the first mirror assembly comprises a first wave plate, and the second mirror assembly comprises a second wave plate; The first wave plate is arranged on the fifth light path direction and close to the first surface, and is used for rotating the polarization direction of the second polarized infrared laser to a target polarization direction; The second wave plate is arranged on the first light path direction and located on the side of the polarized beam splitter away from the resonant cavity assembly, and is used for rotating 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 the rotation direction of the second wave plate, and the rotation angle of the first wave plate is 45 degrees to the rotation angle of the second wave plate.
5. The laser of claim 2, wherein, The mirror assembly comprises a first mirror assembly and a second mirror assembly; The first mirror assembly is used for changing the first polarized residual infrared laser output from the first surface of the frequency doubling element from the sixth light path direction to the third light path direction, so that the first polarized residual infrared laser is incident along the third light path direction into the polarized beam splitter and is output through the polarized beam splitter; The second mirror assembly is used for changing the second polarized residual infrared laser output from the second surface of the frequency doubling element from the fifth light path direction to the fourth light path direction, so that the second polarized residual infrared laser is incident along the fourth light path direction into the polarized beam splitter and is output through the polarized beam splitter.
6. The laser of claim 4, wherein, The first mirror assembly further comprises a first mirror and a first dichroic mirror, and the second mirror assembly further comprises a second mirror and a second dichroic mirror; The first mirror is arranged on the fifth light path direction and located on the side of the first wave plate away from the frequency doubling element, and is used for changing the second polarized infrared laser from the second light path direction to the fifth light path direction; The first dichroic mirror is arranged on the fifth light path direction and located between the first wave plate and the frequency doubling element, and is used for transmitting infrared laser and reflecting green laser; The second mirror is arranged on the first light path direction and located on the side of the second wave plate away from the polarized beam splitter, and is used for changing the first polarized infrared laser from the first light path direction to a seventh light path direction; the seventh light path direction is perpendicular to the first light path direction, and the seventh light path direction is parallel to the second light path direction and has the same direction; The second dichroic mirror is arranged on the sixth light path direction and close to the second surface, and is used for reflecting infrared laser and transmitting green laser.
7. The laser of claim 1, wherein, The laser further comprises: A third wave plate is arranged on the transmission light path of the non-polarized infrared laser and located between the polarized beam splitter and the resonant cavity assembly, and is used for adjusting the proportion of splitting the first polarized infrared laser and the second polarized infrared laser.
8. The laser of claim 1, wherein, The resonant cavity assembly comprises a first grating, a gain optical fiber and a second grating; The first grating is used as a first end of the resonant cavity for receiving the pump light generated by the light source; The gain fiber is arranged on the 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 arranged on the side of the gain fiber away from the first grating, and serves as a second end of the resonant cavity, and is configured to output the non-polarization maintaining infrared laser light.
9. The laser of claim 6, wherein, The laser further comprises: a first lens arranged between the first dichroic mirror and the frequency doubling element, and configured to collimate the light beam transmitted between the first dichroic mirror and the frequency doubling element; and / or a second lens arranged between the frequency doubling element and the second dichroic mirror, and configured to collimate the light beam transmitted between the frequency doubling element and the second dichroic mirror.
10. The laser of claim 6, wherein, The laser further comprises: a first window mirror arranged on the side of the second dichroic mirror away from the frequency doubling element, and configured to output the green laser light output by the second dichroic mirror; and / or a second window mirror arranged on the side of the polarization beam splitter away from the first mirror, and configured to output the infrared laser light output by the polarization beam splitter.