A laser

Abstract

The present application provides a laser, which includes a pump light source, a packaging unit for generating a pulse light beam, a dispersion adjustment unit, and an optical path propagation component located on the optical path between the two; the incident light beam emitted by the pump light source enters the packaging unit through the optical path propagation component and is converted into a pulse light beam; the pulse light beam enters the dispersion adjustment unit through the optical path propagation component, and the pulse light beam enters the diffraction grating to form a first diffraction light beam, and the first diffraction light beam is reflected and translated by a translational ridge prism for a preset distance, and then enters the diffraction grating again to form a second diffraction light beam; the second diffraction light beam is totally reflected by a total reflection mirror and then returns along the original path, and after being diffracted twice by the diffraction grating again, it is coupled into the optical path propagation component to output a pulse light beam after dispersion adjustment; the moving mechanism drives the translational ridge prism to move in the direction of the first diffraction light beam. The laser provided by the present application has a large adjustable pulse width range, a simple structure, and good stability.

Description

Technical Field

[0001] The present application belongs to the technical field of lasers, and more specifically, relates to a laser. Background Art

[0002] In the field of laser technology, ultrafast lasers refer to pulsed lasers with output pulse widths in the order of picoseconds or less, and such ultrafast lasers are widely used in precision micromachining, biomedicine, and scientific research. Usually, all-fiber high-power, large-pulse-energy ultrafast pulse lasers generally use an ultrafast seed source plus a fiber amplifier-level MOPA (Master Oscillator Power-Amplifier) ​​structure. Among them, the quality of the ultrafast seed source directly determines the quality of the final output of the laser amplification system, and the generation of the ultrafast seed source often uses a passive mode-locking scheme. Passive mode-locking schemes generally include saturated absorber passive mode-locking schemes (semiconductor saturated absorber SESAM, graphene, topological insulators, and black scales, etc.), nonlinear polarization rotation schemes (NPR) and nonlinear amplified loop mirror (NALM) schemes. Although this passive mode-locking scheme has the advantages of narrow pulse width, high stability and all-fiber structure in the design of ultrafast lasers, its disadvantage is that the pulse width cannot be flexibly adjusted. If the need to adjust the pulse width is to be achieved, it is necessary to adjust the dispersion during the post-amplification process, which increases the structural complexity and cost.

[0003] In order to achieve adjustable pulses, the industry usually adopts active modulation methods such as electrical adjustment and gain switch. In this active modulation scheme, the laser pulse and frequency are controlled by the circuit. Although the pulse width can be flexibly adjusted and has the characteristics of high stability and fast response, it is difficult to obtain laser pulses below 50ps in this way, which is not conducive to the application of lasers in industrial cold processing. In addition, in addition to the active modulation scheme, the pulse width can be adjusted by changing the dispersion elements in the cavity through certain technical means. However, this method of changing the dispersion characteristics of the dispersion elements in the cavity, such as photonic crystal fiber, dispersion fiber grating, and carbon nanotubes, to achieve adjustable pulse width is often achieved through changes in temperature or stress, and there are problems such as poor stability, narrow adjustable range, poor repeatability and long response time. For example, some people in the industry have proposed to use the optical control adjustment of the reflection bandwidth of the graphene chirped Bragg grating to achieve the output of pulse width adjustable laser, which has the advantages of high adjustment accuracy, wide adjustment range and short response time. But in fact, due to the sensitivity and low long-term stability of graphene, this technology is difficult to apply in industry.

[0004] Therefore, providing an ultrafast laser with adjustable pulse width, wide adjustment range, short response time, good stability and the ability to truly meet the needs of industrial applications has become an urgent problem to be solved in the industry. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a laser to solve the technical problem in the prior art that the pulse width of an ultrafast laser cannot be flexibly adjusted.

[0006] To achieve the above purpose, the technical solution adopted in this application is: to provide a laser, including:

[0007] Pump light source,

[0008] A packaging unit for generating a pulsed light beam;

[0009] a dispersion adjustment unit, the dispersion adjustment unit comprising a diffraction grating, a translational roof prism, a total reflection mirror and a moving mechanism, the translational roof prism being mounted on the moving mechanism; and,

[0010] An optical path propagation component, the optical path propagation component is located on the optical path between the packaging unit and the dispersion adjustment unit;

[0011] Among them, the incident light beam emitted by the pump light source generates a continuous light beam through the optical path propagation component and enters the packaging unit, and the packaging unit converts the continuous light beam into a pulse light beam; the pulse light beam enters the dispersion adjustment unit through the optical path propagation component, and the pulse light beam enters the diffraction grating to form a first diffraction light beam. After the first diffraction light beam is reflected and translated by a preset distance by a translational roof prism, it is again injected into the diffraction grating to form a second diffraction light beam directed to a total reflection mirror; the second diffraction light beam is totally reflected by the total reflection mirror and returns along the original path, and after being diffracted twice by the diffraction grating again, it is coupled into the optical path propagation component to output a pulse light beam after dispersion adjustment; the moving mechanism can drive the translational roof prism to move along the direction of the first diffraction light beam.

[0012] Optionally, the optical path propagation component includes a first polarization-maintaining collimator and a second polarization-maintaining collimator connected along the optical path, the packaging unit is spatially coupled to the first polarization-maintaining collimator, and the dispersion adjustment unit is spatially coupled to the second polarization-maintaining collimator.

[0013] Optionally, the packaging unit includes a saturable absorber, a fixing sleeve, and a focusing lens;

[0014] The fixed sleeve has a mounting cavity, the coupling end of the first polarization-maintaining collimator extends into the fixed sleeve, the saturable absorber is mounted on the inner wall of the mounting cavity, and the saturable absorber and the first polarization-maintaining collimator are arranged relatively and spaced apart; the focusing lens is built into the mounting cavity and is located between the saturable absorber and the first polarization-maintaining collimator.

[0015] Optionally, the focusing lens is a biconvex element.

[0016] Optionally, the moving mechanism includes a moving platform and a stepper motor connected to the moving platform, the translational roof prism is fixed on the moving platform, and the stepper motor is controlled to drive the moving platform to move, so as to drive the translational roof prism to move along the direction of the first diffraction light beam.

[0017] Optionally, a pulsed light beam is output from a second polarization-maintaining collimator and enters a diffraction grating to form a first diffraction light beam; after the first diffraction light beam is reflected by a translational roof prism and translated by a preset distance, it is reflected back to the diffraction grating in a direction opposite to the first diffraction light beam, and is diffracted twice by the diffraction grating to form a second diffraction light beam; after the second diffraction light beam is totally reflected by a total reflection mirror, it returns along the original path, and is diffracted twice by the diffraction grating again before being coupled into the second polarization-maintaining collimator.

[0018] Optionally, the reflection surface of the total reflection mirror is perpendicular to the direction of the second diffraction light beam; when the diffraction grating is a transmission type diffraction grating, the translational roof prism and the total reflection mirror are respectively arranged on both sides of the ruled line plane of the diffraction grating; when the diffraction grating is a reflection type diffraction grating, the translational roof prism and the total reflection mirror are both arranged on the side of the diffraction grating facing the second polarization-maintaining collimator, and the translational roof prism is located between the diffraction grating and the total reflection mirror.

[0019] Optionally, the optical path propagation component also includes a polarization-maintaining wavelength division multiplexer, a doped polarization-maintaining optical fiber and a polarization-maintaining output coupler. The incident light beam emitted by the pump light source is transmitted to the polarization-maintaining wavelength division multiplexer through the optical fiber, coupled into the doped polarization-maintaining optical fiber, and then enters the second polarization-maintaining collimator after passing through the polarization-maintaining output coupler.

[0020] Optionally, the signal end of the polarization-maintaining wavelength division multiplexer is connected to the first polarization-maintaining collimator, the pump end of the polarization-maintaining wavelength division multiplexer is connected to the pump light source, and the common end of the polarization-maintaining wavelength division multiplexer is connected to the doped polarization-maintaining optical fiber.

[0021] Optionally, a birefringent crystal is provided in the polarization-maintaining output coupler, the combining end of the polarization-maintaining output coupler is connected to the second polarization-maintaining collimator, the first branching end of the polarization-maintaining output coupler is connected to the doped polarization-maintaining optical fiber, and the second branching end of the polarization-maintaining output coupler is the output end for outputting the dispersion-adjusted pulse light beam.

[0022] The beneficial effect of the laser provided by the present application is that, compared with the prior art, since the laser includes a packaging unit and a dispersion adjustment unit, the two together form the resonant cavity of the laser, so after the incident light beam emitted by the pump light source enters the packaging unit through the light propagation component, it can be converted into a stable ultra-short pulse light beam through passive mode locking. Then, after the pulse light beam enters the dispersion adjustment unit, the translational ridge prism is driven by the moving mechanism to move in the direction of the first diffraction light beam, thereby controlling the change of the spacing between the translational ridge prism and the diffraction grating, and controlling the dispersion amount in the resonant cavity, thereby realizing the adjustment of the laser pulse width from femtoseconds to picoseconds. In other words, the technical solution of the present application is a pulse width adjustable ultrafast laser technology based on controlling the dispersion amount of the diffraction grating in the cavity. The technology uses the passive locking method of the saturable absorber of the packaging unit to generate an ultrashort pulse light beam, and then drives the translational ridge prism to change the distance with the diffraction grating through the moving mechanism to realize the adjustment and control of the dispersion amount in the resonant cavity, thereby realizing the continuous adjustment of the laser pulse width of the external pulse light beam from femtoseconds to picoseconds, which effectively solves the problems existing in the currently common adjustable ultrashort pulse width lasers, such as the pulse width is too wide to meet industrial needs, poor stability, narrow adjustable range and long response time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 A schematic diagram of the optical path structure of a laser provided in an embodiment of the present application;

[0025] Figure 2 A cross-sectional view of a packaging unit of a laser provided in an embodiment of the present application;

[0026] Figure 3 A schematic diagram of the optical path structure of a dispersion adjustment unit of a laser provided in an embodiment of the present application;

[0027] Figure 4 A schematic diagram of the optical path structure of a dispersion adjustment unit of a laser provided in another embodiment of the present application.

[0028] Description of Figure Numbers:

[0029] DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0031] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0032] It should also be noted that the directional terms such as left, right, up and down in the embodiments of the present application are merely relative concepts or are based on the normal use status of the product, and should not be considered as restrictive.

[0033] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0034] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] An embodiment of the present application provides a laser.

[0038] See also Figures 1 to 3 In one embodiment, the laser includes a pump light source 100, a packaging unit 200, a dispersion adjustment unit 300, and an optical path propagation component 400. The packaging unit 200 is used to generate a pulsed light beam; the dispersion adjustment unit 300 includes a diffraction grating 310, a translational roof prism 320, a total reflection mirror 330, and a moving mechanism (not shown), and the translational roof prism 320 is mounted on the moving mechanism; the optical path propagation component 400 is located on the optical path between the packaging unit 200 and the dispersion adjustment unit 300. The incident light beam emitted by the pump light source 100 generates a continuous light beam through the optical path propagation component 400 and enters the packaging unit 200, and the packaging unit 200 converts the continuous light beam into a pulse light beam; the pulse light beam passes through the optical path propagation component 400 and enters the dispersion adjustment unit 300, and the pulse light beam enters the diffraction grating 310 to form a first diffraction light beam, and the first diffraction light beam is reflected and translated by the translational roof prism 320 for a preset distance, and then enters the diffraction grating 310 again to form a second diffraction light beam directed to the total reflection mirror 330; the second diffraction light beam is totally reflected by the total reflection mirror 330 and then returns along the original path, and is coupled into the optical path propagation component 400 after being diffracted twice by the diffraction grating 310 again, so as to output the pulse light beam after dispersion adjustment; the moving mechanism can drive the translational roof prism 320 to move along the direction of the first diffraction light beam. Here, the pulse light beam emitted from the optical path propagation component 400 to the diffraction grating 310 is set at an angle with the ruled plane of the diffraction grating 310. The pulse light beam is parallel to the second diffraction light beam but has an opposite optical path direction. The first diffraction light beam is parallel to the light beam reflected and translated by the translational roof prism 320 and then emitted to the diffraction grating 310 but has an opposite direction.

[0039] It should be noted that, in this embodiment, the laser is a fiber laser, and is a fiber ultrafast laser with adjustable pulse width. Among them, the packaging unit 200 is specifically a SESAM (Semiconductor Saturable Absorber Mirror) packaging unit 200. In the field of lasers, using SESAM to achieve passive mode locking is a common means of obtaining ultrashort pulses. The principle of this method is that through the loss mechanism of the saturable absorber 210, due to the strong energy at the center of the pulse, the SESAM saturable absorber 210 is in a bleaching state, with low energy loss, and can be reflected back into the cavity for continued amplification; while the energy on both sides of the pulse is weak, showing the characteristics of unsaturated absorption, and large loss. In this way, during the operation of the laser, the energy at the center of the pulse will be continuously amplified, while the energy on both sides of the pulse will be continuously suppressed. After multiple cycles, a stable ultrashort pulse can be finally formed.

[0040] Based on this structural design, in the present embodiment, since the laser includes a packaging unit 200 and a dispersion adjustment unit 300, which together form a resonant cavity of the present laser, the incident light beam emitted by the pump light source 100 can be converted into a stable ultrashort pulse light beam through a passive mode locking method after entering the packaging unit 200 through the light propagation component. Then, after the pulse light beam enters the dispersion adjustment unit 300, the translational roof prism 320 is driven by the moving mechanism to move in the direction of the first diffraction light beam, thereby controlling the change in the spacing between the translational roof prism 320 and the diffraction grating 310, and controlling the dispersion amount in the resonant cavity, thereby realizing the adjustment of the laser pulse width from femtoseconds to picoseconds. In other words, the technical solution of the present application is a pulse width adjustable ultrafast laser technology based on controlling the dispersion amount of the diffraction grating 310 in the cavity. The technology uses the passive locking method of the saturable absorber 210 of the packaging unit 200 to generate an ultrashort pulse light beam, and then drives the translational ridge prism 320 to change the distance with the diffraction grating 310 through the moving mechanism to achieve the adjustment and control of the dispersion amount in the resonant cavity, thereby achieving the continuous adjustment of the laser pulse width of the pulse light beam output to the outside from femtoseconds to picoseconds, effectively solving the problems of the currently common adjustable ultrashort pulse width lasers, such as the pulse width is too wide to meet industrial needs, poor stability, narrow adjustable range and long response time.

[0041] See also Figures 1 to 3In this embodiment, the optical path propagation component 400 includes a first polarization-maintaining collimator 410 and a second polarization-maintaining collimator 420 connected along the optical path, the packaging unit 200 is spatially coupled with the first polarization-maintaining collimator 410, and the dispersion adjustment unit 300 is spatially coupled with the second polarization-maintaining collimator 420. Here, the first polarization-maintaining collimator 410 and the second polarization-maintaining collimator 420 are both used to output high-quality collimated linearly polarized laser beams, so that the pulse beam emitted from the packaging unit 200 can be coupled into the optical fiber, and then coupled into the second polarization-maintaining collimator 420 through other components in the optical path propagation component 400, and then enter the dispersion adjustment unit 300 for adjustment, so as to achieve the narrowest pulse width of the pulse beam output to the outside.

[0042] Furthermore, if Figure 2 As shown, in this embodiment, specifically, the packaging unit 200 includes a saturable absorber 210, a fixed sleeve 220 and a focusing lens 230; the fixed sleeve 220 has a mounting cavity 240, the coupling end of the first polarization-maintaining collimator 410 extends into the fixed sleeve 220, the saturable absorber 210 is mounted on the inner wall of the mounting cavity 240, and the saturable absorber 210 and the first polarization-maintaining collimator 410 are arranged relatively spaced apart; the focusing lens 230 is built into the mounting cavity 240 and is located between the saturable absorber 210 and the first polarization-maintaining collimator 410. Here, the saturable absorber 210, i.e., SESAM, is specifically a reflective device, and its main function is to generate a self-starting ultrashort pulse beam by passive mode locking. The fixed sleeve 220 is mainly composed of a bottom plate 221 and an outer cover 222. The outer cover 222 has a groove that is open on the side away from the first polarization-maintaining collimator 410. The bottom plate 221 seals and covers the opening of the groove, thereby forming a mounting cavity 240 with the outer cover 222. The coupling end of the first polarization-maintaining collimator 410 extends into the bottom of the groove. The saturable absorber 210 is mounted on the bottom plate 221 and is opposite to the first polarization-maintaining collimator 410. The focusing lens 230 is arranged between the saturable absorber 210 and the first polarization-maintaining collimator 410. In addition, the fixed sleeve 220 is preferably made of a metal material. In addition to having the function of fixing the saturable absorber 210 and the focusing lens 230, the fixed sleeve 220 can also have good thermal conductivity, so that the heat of the saturable absorber 210 can be conducted away, thereby ensuring the stability and reliability of the operation of the laser. Of course, in other embodiments, the fixing sleeve 220 may also be made of other hard, light-proof materials with good thermal conductivity.

[0043] For further information, see Figure 1 and Figure 2In this embodiment, the focusing lens 230 is preferably a biconvex element. Here, the function of the focusing lens 230 is to expand the spot of the laser beam to ensure that the size of the laser spot at the saturable absorber 210 is 0.5-1.0 mm. However, the present design is not limited thereto. In other embodiments, the focusing lens 230 can also be other optical elements that can achieve focusing and spot expansion functions.

[0044] In this embodiment, specifically, the moving mechanism includes a moving platform (not shown) and a stepper motor (not shown) connected to the moving platform, and the translational roof prism 320 is fixed on the moving platform, and the stepper motor is controlled to drive the moving platform to move, so as to drive the translational roof prism 320 to move along the direction of the first diffraction beam. It can be understood that since 1um light presents a strong positive dispersion in the quartz medium, the pulse width of the pulsed light beam output by the passive mode locking method of the saturable absorber 210 is dispersed, and it is necessary to disperse it outside the cavity, and the existing dispersion removal method is often to change the dispersion characteristics of the dispersion element in the resonant cavity by changing the temperature or stress, which will increase the complexity and cost of the laser. However, in the present application, by installing the translational roof prism 320 on a moving platform driven by a high-precision stepper motor, the spacing between the translational roof prism 320 and the diffraction grating 310 can be precisely controlled, so that the change of the dispersion amount can be precisely controlled, and then the laser pulse width of the pulsed light beam can be adjusted from femtoseconds to picoseconds. Here, the total reflection mirror 330 is a wide-bandwidth total reflection mirror 330, and the translational roof prism 320 is composed of two reflection mirrors glued vertically to each other; the translational roof prism 320 and the total reflection mirror 330 fully reflect the laser within the range of ±10nm of the central wavelength, and the reflectivity is greater than 99%.

[0045] See also Figure 3 In this embodiment, the pulsed light beam is output from the second polarization-maintaining collimator 420 and enters the diffraction grating 310 to form a first diffraction light beam; after the first diffraction light beam is reflected by the translational roof prism 320 and translated by a preset distance, it is reflected back to the diffraction grating 310 in the opposite direction of the first diffraction light beam, and forms a second diffraction light beam after being diffracted twice by the diffraction grating 310; the second diffraction light beam is totally reflected by the total reflection mirror 330 and returns along the original path, and is coupled into the second polarization-maintaining collimator 420 after being diffracted twice by the diffraction grating 310 again. In other words, after the pulsed light beam is output from the second polarization-maintaining collimator 420, it is diffracted four times by the diffraction grating 310 on the forward and reverse optical paths, and finally can be coupled into the second polarization-maintaining collimator 420, thereby realizing the output of the dispersion-adjusted pulsed light beam.

[0046] Specifically, the reflection surface of the total reflection mirror 330 is perpendicular to the direction of the second diffracted light beam, so as to ensure that the light beam can return along the original path. In this embodiment, the diffraction grating 310 is specifically a transmission type diffraction grating 310, and the translational roof prism 320 and the total reflection mirror 330 are respectively arranged on both sides of the ruled plane of the diffraction grating 310. Figure 3 As shown. Figure 4 In another embodiment shown, when the diffraction grating 310 is a reflective diffraction grating 310 , the translational roof prism 320 and the total reflection mirror 330 are both disposed on the side of the diffraction grating 310 facing the second polarization-maintaining collimator 420 , and the translational roof prism 320 is located between the diffraction grating 310 and the total reflection mirror 330 .

[0047] Here, the diffraction grating 310 is an optical plate with regular grooves or lines on its surface, and a spectroscopic device that can cause the incident light to produce periodic spatial modulation. Specifically, the second-order dispersion caused by the transmission of 1030nm light in the quartz medium is 0.0217ps² / m; and in this embodiment, preferably, the pulse repetition frequency is 30MHz, the corresponding optical cavity length is about 3.3 meters, and the total length of the optical fiber is about 2.5 meters, and the positive dispersion provided by the corresponding quartz is 0.0543ps². The dispersion provided by the diffraction grating 310 can be calculated according to the following formula (1):

[0048] (1)

[0049] Wherein, GDD is group delay dispersion, d is the vertical distance between the diffraction grating 310 and the translational roof prism 320, λ is the wavelength, c is the speed of light, Λ is the grating constant, and θr is the diffraction angle.

[0050] To compensate for the positive dispersion of the system, the line density on the grating, i.e., the grating constant, is usually in the range of 300 lines / mm to 1200 lines / mm or others. In the present embodiment, the line density of the diffraction grating 310 can be further preferably 300 lines / mm, and the spacing between the translational roof prism 320 and the diffraction grating 310 is preferably 7.5 cm. When the spacing between the diffraction grating 310 and the translational roof prism 320 is adjusted to the right position, the negative dispersion provided by the diffraction grating 310 just compensates for the original positive dispersion. At this time, the total dispersion of the entire system is zero, so that the pulse width of the pulsed light beam output to the outside is the narrowest; moreover, by changing the spacing d, the dispersion amount of the output pulsed light beam can be changed, thereby realizing continuous adjustment of the pulse width from femtoseconds to picoseconds.

[0051] The above design is based on Figure 3 The method for adjusting the pulse-adjustable ultrafast laser of the transmission grating shown in FIG. Figure 4The laser based on the reflective diffraction grating 310 shown can also achieve the same effect, and its adjustment method is basically the same as that of the transmissive diffraction grating 310, so it will not be repeated.

[0052] See also Figure 1 In this embodiment, the optical path propagation component 400 further includes a polarization-maintaining wavelength division multiplexer 430, a doped polarization-maintaining optical fiber 440, and a polarization-maintaining output coupler 450. The incident light beam emitted by the pump light source 100 is transmitted to the polarization-maintaining wavelength division multiplexer 430 through an optical fiber, and coupled into the doped polarization-maintaining optical fiber 440, and then enters the second polarization-maintaining collimator 420 after passing through the polarization-maintaining output coupler 450. Here, the pump light source 100 is specifically a single-mode semiconductor pump pump light source 100. The energy of the pump light source 100 can be transmitted to the polarization-maintaining wavelength division multiplexer 430 through a single-mode optical fiber, and further coupled into the doped polarization-maintaining optical fiber 440. Among them, the doped polarization-maintaining optical fiber can be a polarization-maintaining optical fiber doped with Yb or Nd rare earth ions, with a length ranging from 0.3m to 1.0m, and can excite a 1.0um laser. Specifically in this embodiment, a polarization-maintaining active optical fiber doped with Yb rare earth ions can be preferably used, and its length is preferably 0.5m.

[0053] Furthermore, in this embodiment, the signal end of the polarization-maintaining wavelength division multiplexer 430 is connected to the first polarization-maintaining collimator 410, the pump end of the polarization-maintaining wavelength division multiplexer 430 is connected to the pump light source 100, and the common end of the polarization-maintaining wavelength division multiplexer 430 is connected to the doped polarization-maintaining optical fiber 440. In this way, through a polarization-maintaining wavelength division multiplexer 430, lights of different wavelengths can be coupled into one optical fiber for output or reverse use as demultiplexing, and the input and output of the polarization-maintaining wavelength division multiplexer 430 both use polarization-maintaining optical fibers, so that the laser can be suitable for different application occasions.

[0054] Furthermore, in this embodiment, a birefringent crystal is provided inside the polarization-maintaining output coupler 450, a combined end of the polarization-maintaining output coupler 450 is connected to the second polarization-maintaining collimator 420, a first branch end of the polarization-maintaining output coupler 450 is connected to the doped polarization-maintaining optical fiber, and a second branch end of the polarization-maintaining output coupler 450 is an output end for outputting a pulsed light beam after dispersion adjustment. Specifically, the polarization-maintaining output coupler 450 is a 1×2 coupling device, and the birefringent crystal provided inside the polarization-maintaining output coupler 450 has a polarizer function, which can convert the laser light incident into the polarization-maintaining output coupler 450 into a linearly polarized light output, so that the pulsed light beam can maintain linear polarization during transmission and be transmitted along the slow axis direction of the polarization-maintaining optical fiber. The coupling ratio of the polarization-maintaining output coupler 450 includes but is not limited to 70:30, 80:20, 90:10, etc. In the present embodiment, a polarization-maintaining coupler with a coupling ratio of 70:30 is preferably used, that is, the first branch end connected to the doped polarization-maintaining optical fiber outputs 30% of the laser energy, and the other second branch end for outputting a dispersion-adjusted ultrashort pulse beam outputs 70% of the laser energy.

[0055] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A laser, characterized in that: include: Pump light source; A packaging unit, used to generate a pulsed light beam, the packaging unit comprising a saturable absorber, a fixing sleeve and a focusing lens, the fixing sleeve having a mounting cavity, the saturable absorber being mounted on an inner wall of the mounting cavity, and the focusing lens being built in the mounting cavity; a dispersion adjustment unit, the dispersion adjustment unit comprising a diffraction grating, a translational roof prism, a total reflection mirror and a moving mechanism, the translational roof prism being mounted on the moving mechanism; and an optical path propagation component, the optical path propagation component is located on the optical path between the packaging unit and the dispersion adjustment unit, the optical path propagation component comprises a first polarization-maintaining collimator and a second polarization-maintaining collimator connected along the optical path, the packaging unit is spatially coupled with the first polarization-maintaining collimator, a coupling end of the first polarization-maintaining collimator extends into the fixing sleeve, and the saturable absorber and the first polarization-maintaining collimator are arranged with a relative interval, the focusing lens is located between the saturable absorber and the first polarization-maintaining collimator, and the dispersion adjustment unit is spatially coupled with the second polarization-maintaining collimator; The incident light beam emitted by the pump light source generates a continuous light beam through the optical path propagation component and enters the packaging unit, and the packaging unit converts the continuous light beam into a pulse light beam; the pulse light beam passes through the optical path propagation component and enters the dispersion adjustment unit, and the pulse light beam enters the diffraction grating to form a first diffraction light beam, and the first diffraction light beam is reflected and translated by the translational roof prism for a preset distance, and then enters the diffraction grating again to form a second diffraction light beam directed to the total reflection mirror; the second diffraction light beam is totally reflected by the total reflection mirror and then returns along the original path, and is coupled into the optical path propagation component after being diffracted twice by the diffraction grating again, so as to output the dispersion-adjusted pulse light beam to the outside; The moving mechanism can drive the translational roof prism to move along the direction of the first diffraction light beam; The pulsed light beam is output from the second polarization-maintaining collimator and enters the diffraction grating to form the first diffraction light beam; after being reflected by the translational roof prism and translated by a preset distance, the first diffraction light beam is reflected back to the diffraction grating in the opposite direction to the first diffraction light beam, and is diffracted twice by the diffraction grating to form the second diffraction light beam; the second diffraction light beam is totally reflected by the total reflection mirror and returns along the original path, and is diffracted twice by the diffraction grating again and coupled into the second polarization-maintaining collimator.

2. The laser according to claim 1, characterized in that The focusing lens is a biconvex element.

3. The laser according to claim 2, characterized in that The moving mechanism includes a moving platform and a stepper motor connected to the moving platform. The translational roof prism is fixed on the moving platform. The stepper motor is controlled to drive the moving platform to move, so as to drive the translational roof prism to move along the direction of the first diffraction light beam.

4. The laser according to claim 1, characterized in that The reflection surface of the total reflection mirror is perpendicular to the direction of the second diffraction light beam; when the diffraction grating is a transmission-type diffraction grating, the translational roof prism and the total reflection mirror are respectively arranged on both sides of the ruled line plane of the diffraction grating; when the diffraction grating is a reflection-type diffraction grating, the translational roof prism and the total reflection mirror are both arranged on the side of the diffraction grating facing the second polarization-maintaining collimator, and the translational roof prism is located between the diffraction grating and the total reflection mirror.

5. The laser according to any one of claims 1 to 4, characterized in that: The optical path propagation component also includes a polarization-maintaining wavelength division multiplexer, a doped polarization-maintaining optical fiber and a polarization-maintaining output coupler. The incident light beam emitted by the pump light source is transmitted to the polarization-maintaining wavelength division multiplexer through an optical fiber, coupled into the doped polarization-maintaining optical fiber, and then enters the second polarization-maintaining collimator after passing through the polarization-maintaining output coupler.

6. The laser according to claim 5, characterized in that The signal end of the polarization-maintaining wavelength division multiplexer is connected to the first polarization-maintaining collimator, the pump end of the polarization-maintaining wavelength division multiplexer is connected to the pump light source, and the common end of the polarization-maintaining wavelength division multiplexer is connected to the doped polarization-maintaining optical fiber.

7. The laser according to claim 5, characterized in that A birefringent crystal is disposed inside the polarization-maintaining output coupler, a combining end of the polarization-maintaining output coupler is connected to the second polarization-maintaining collimator, a first branching end of the polarization-maintaining output coupler is connected to the doped polarization-maintaining optical fiber, and a second branching end of the polarization-maintaining output coupler is an output end for outputting a dispersion-adjusted pulsed light beam.

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