A semiconductor-pumped cesium vapor mode-locked laser and a method for generating ultra-short pulse laser

Abstract

The application provides a semiconductor-pumped cesium vapor mode-locked laser and a method for generating ultra-short pulse laser. The laser comprises a semiconductor pumping source for outputting a pumping beam; a pumping light shaping system for receiving the pumping light and converging the pumping light to the middle part of a cesium vapor cell; the cesium vapor cell for performing gain on the shaped pumping light to generate gain laser; and a mode-locked resonant structure for outputting mode-locked laser after oscillation mode-locking of the gain laser. The pumping light emitted by the semiconductor pumping source is focused into the cesium vapor cell through the pumping light shaping system, and after gain on the cesium vapor as gain medium, the pumping light enters the mode-locked resonant structure to oscillate to form the cesium vapor mode-locked laser. The application has picosecond pulse width, and greatly improves the peak power of the current alkali metal laser.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of ultrashort pulse, and particularly relates to a semiconductor-pumped cesium vapor mode-locked laser and a method for generating ultrashort pulse laser. BACKGROUND

[0002] High peak power picosecond lasers have important application value and development prospect in scientific frontiers, industrial precision machining, laser communication and medical cosmetology. At present, devices for obtaining high peak power ultrashort pulse lasers generally include titanium sapphire lasers, all-solid-state lasers and fiber lasers. Generally, a mode-locked laser based on an optical fiber or a solid medium is used as a seed source, and power is boosted through regenerative amplification or traveling wave amplification. In the traveling wave amplification process, a titanium sapphire laser is difficult to support high power laser output due to its low thermal conductivity; an optical fiber laser is difficult to continuously improve the peak power due to the nonlinear effect and damage in the optical fiber; and an all-solid-state laser is the main way to obtain high peak power ultrashort pulses at present. However, the thermal effect in the solid-state amplification technology is a key factor affecting further amplification and beam quality, and with the increase of energy and peak power, most high-energy lasers work at an extremely low repetition frequency, and many are large scientific devices with high cost. For example, a laser with a single pulse energy of 16.7 J and a peak power of 170 TW, but the repetition frequency is only 0.02 Hz.

[0003] At present, most DPALs work in continuous mode (CW), however, for some special applications, such as space optics, medical diagnosis, scientific research, ultra-precision machining, and nonlinear optical applications, ultrashort pulses with high peak power and high single pulse energy are needed, therefore, the research on ultrashort pulse DPAL will have great application value and development prospect.

[0004] There are mainly two ways to obtain ultrashort pulses, namely Q-switching and mode-locking. At present, there are few research institutions studying Q-switching of DPAL, and only a few reports. For example, in 2019, Chen Fei team of Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences added an acousto-optic modulator in the resonant cavity of Cs-DPAL, and realized pulsed laser output with a power of about 0.2 W, a repetition frequency of 1 MHz and a pulse width of 238 ns. In the same year, Masamori Endo of Tokyo University in Japan used the method of electro-optic cavity emptying to obtain pulsed laser output of Cs-DPAL with a repetition frequency of 100 Hz, a pulse width of 14 ns and a peak power of 77 W. Although the pulse energy and peak power are greatly improved (about 25 times) compared with continuous operation, it is limited by the upper level lifetime of alkali metal (Cs: about 30 ns), which shows that cesium (including other alkali metals) vapor lasers are not suitable for pulsed energy storage type lasers like Nd:YAG (upper level lifetime: about 230 μs), but are more suitable for continuous operation.

[0005] And by the mode-locked way obtains the super short pulse, can work in the continuous mode, and the pulse width obtained is narrower (about hundred picoseconds), compared with the pulse width obtained in the literature, the pulse width is reduced by two orders of magnitude, which will make the peak power increase by two orders of magnitude, and will reach more than several kW.If you want to get higher peak power laser, you can use the power amplifier scheme to further improve the pulse energy and peak power with the mode-locked pulse laser as the seed light.Sadly, the semiconductor-pumped cesium vapor mode-locked laser has not been reported. SUMMARY

[0006] In view of the problem that high peak power super short pulse alkali metal laser is difficult to realize in the prior art, the present application provides a semiconductor-pumped cesium vapor mode-locked laser and a method for generating super short pulse laser.The present application has universality, can provide theoretical support for mode-locked realization of other alkali metals, and realizes an alkali metal picosecond pulse laser with good beam quality, high efficiency and strong amplification.The present application can be widely applied in scientific frontiers, detection and elimination of space debris, industrial precision machining, laser communication and medical cosmetology and other fields.

[0007] The technical means adopted by the present application are as follows:

[0008] In one aspect, the present application provides a semiconductor-pumped cesium vapor mode-locked laser, comprising:

[0009] A semiconductor pumping source for outputting a pump light beam;

[0010] A pump light shaping system for receiving the pump light and converging it to the middle part of the cesium vapor cell;

[0011] A cesium vapor cell for gaining the shaped pump light to generate gain laser;

[0012] A mode-locked resonant structure for oscillating and mode-locking the gain laser to output mode-locked laser, the mode-locked resonant structure comprising:

[0013] A dichroic mirror arranged on the output light path of the pump light shaping system,

[0014] A first high reflector receiving the gain laser at a certain angle and reflecting the gain laser once,

[0015] A second high reflector receiving the reflected laser of the first high reflector and reflecting the laser twice,

[0016] A saturable absorber for super short pulse mode-locking of the gain laser,

[0017] And an output mirror arranged on the reflected light path of the dichroic mirror;

[0018] The pump light emitted by the semiconductor pump source is focused into the cesium vapor cell by a pump light shaping system, is amplified by taking cesium vapor as a gain medium, is oscillated in a mode-locked resonant structure, and finally outputs mode-locked laser from an output mirror.

[0019] Based on the above technical scheme, preferably, the saturable absorber is arranged on the reflection light path of the first high-reflection mirror and the second high-reflection mirror.

[0020] Based on the above technical scheme, preferably, the first high-reflection mirror, the second high-reflection mirror and the saturable absorber form a Z-shaped folded cavity structure.

[0021] Based on the above technical scheme, preferably, the saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus and molybdenum disulfide.

[0022] Based on the above technical scheme, preferably, the cesium vapor cell is placed in a temperature control furnace, the inside of which is filled with cesium vapor as a gain medium and mixed with a certain amount of buffer gas, the buffer gas being one of methane, ethane and helium or a mixed gas of helium and alkane.

[0023] Based on the above technical scheme, preferably, the pump light has a linewidth less than or equal to 0.1 nm.

[0024] Based on the above technical scheme, preferably, the output mirror is an output coupling mirror.

[0025] The dichroic mirror is a plane mirror or a polarization prism, the transmittance of which to the pump light wavelength is greater than 99%, and the reflectivity of which to the laser wavelength is greater than 99%.

[0026] The first high-reflection mirror and the second high-reflection mirror are concave mirrors with a certain curvature and a reflectivity to the laser wavelength greater than 99%.

[0027] On the other hand, the application also provides a method for generating ultra-short pulse laser, which is realized based on the above laser, and comprises the following steps:

[0028] Outputting pump light by a semiconductor pump source, the pump light having a linewidth less than or equal to 0.1 nm;

[0029] Accommodating the pump light by a pump light shaping system and converging the pump light to the middle part of a cesium vapor cell;

[0030] Generating gain laser by the cesium vapor cell to the shaped pump laser;

[0031] Outputting mode-locked laser after oscillating and mode-locking the gain laser by a mode-locked resonant structure, the mode-locked resonant structure comprising:

[0032] A dichroic mirror arranged on the output light path of the pump light shaping system,

[0033] a first high reflectivity mirror which receives the gain laser at an angle and reflects the gain laser once,

[0034] a second high reflectivity mirror which receives the reflected laser of the first high reflectivity mirror and reflects the laser twice,

[0035] a saturable absorber which mode-locks the gain laser,

[0036] and an output mirror arranged on the reflected light path of the dichroic mirror.

[0037] Based on the above technical solution, preferably, the dichroic mirror, the first high reflectivity mirror, the second high reflectivity mirror, the output mirror and the saturable absorber form a Z-shaped folded cavity structure; or,

[0038] The saturable absorber is arranged on the reflected light path of the first high reflectivity mirror and the second high reflectivity mirror.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] 1. The semiconductor-pumped cesium vapor mode-locked laser provided by the present application is universal and can provide theoretical support for mode-locked lasers of other alkali metals, and realizes an alkali metal picosecond pulse laser with good beam quality, high efficiency and strong amplification.

[0041] 2. The present application fills the research gap of ultra-short pulse alkali metal lasers, uses a diode laser as a pump source, an alkali metal vapor with a large gain coefficient as a gain medium, and a saturable absorber as a passive mode-locked device, and obtains an alkali metal ultra-short pulse laser with higher peak power, which has the characteristics of picosecond pulse width, high peak power, high efficiency, good beam quality, good amplification, and reliable use. It has important application value and development prospect in scientific frontier, detection and elimination of space debris, industrial precision machining, laser communication and medical beauty, etc.

[0042] Based on the above reasons, the present application can be widely popularized in the fields of detection and elimination of space debris, industrial precision machining, laser communication and medical beauty, etc. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0044] Figure 1The structure schematic diagram of the semiconductor-pumped cesium vapor mode-locked laser provided for the embodiment 1 and 2 of the present application.

[0045] Figure 2 The structure schematic diagram of the semiconductor-pumped cesium vapor mode-locked laser provided for the embodiment 3 of the present application.

[0046] In the figure: 1, semiconductor pumping source; 2, pump light shaping system; 3, cesium vapor cell; 4, output mirror; 5, dichroic mirror; 6, first high reflector; 7, second high reflector; 8, saturable absorber. DETAILED DESCRIPTION

[0047] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0048] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0049] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0050] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all suitable modifications and equivalents can be resorted to falling within the scope of the application. Unless otherwise indicated herein, the procedures and techniques of conventional chemistry, biochemistry, molecular biology, microbiology, recombinant DNA, immunology, and pharmacology, which are within the skill of the art, can be used. Unless otherwise indicated herein, the nomenclature utilized in connection with, and the parameters described herein are consistent with, those of the art. As used herein, the following terms have the following meanings.

[0051] In the description of the present application, it is to be understood that the orientation or positional relationships indicated by orientation words such as "front", "back", "upper", "lower", "left", "right", "transverse", "vertical", "horizontal", and "top", "bottom" and the like are generally based on the orientation or positional relationships shown in the drawings, and are merely for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application. The orientation words "inner", "outer" refer to the inner and outer relative to the contour of the parts themselves.

[0052] For the convenience of description, spatial relative terms such as "above", "upper", "on", "top", "bottom", and the like can be used herein to describe the spatial relationship of one device or feature to another device or feature as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations of the devices in use or operation in addition to the orientation of the devices described in the drawings. For example, if the devices in the drawings are inverted, the device described as "above" or "on" the other device or structure will be positioned "below" or "under" the other device or structure. Thus, the exemplary term "above" can include both the "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0053] In addition, it should be noted that the use of "first", "second", and the like words to qualify elements does not have a special meaning, and therefore cannot be understood as limiting the scope of protection of the present application, unless otherwise stated.

[0054] The application discloses a kind of semiconductor pumped cesium vapor mode-locked lasers, comprising: semiconductor pump source, pump light shaping system, cesium vapor cell, output mirror, dichroic mirror, first high reflector, saturable absorber and second high reflector.Wherein output mirror, dichroic mirror, first high reflector, saturable absorber and second high reflector constitute mode-locked resonant structure.Laser beam output by semiconductor pump source is incident into cesium vapor cell from dichroic mirror after passing through pump light shaping system, and pulse laser oscillates in mode-locked resonant cavity, to realize mode-locked laser output, pulse width is picosecond order, and finally mode-locked pulse laser is output from output mirror.

[0055] Based on the above technical solution, preferably, the pump light shaping system is a lens group, wherein the number of lenses is greater than or equal to 1.The pump light emitted by the semiconductor pump source is focused into the cesium vapor cell through the lens group.The semiconductor pump source outputs narrow linewidth laser as the pump source of the semiconductor pumped cesium vapor mode-locked laser, with a center wavelength of 852.3 nm and a linewidth less than or equal to 0.1 nm.

[0056] Based on the above technical solution, preferably, the cesium vapor cell is filled with cesium vapor as a gain medium and a certain amount of buffer gas;the gain cell is placed in a temperature control furnace;and the buffer gas is one of methane (CH4), ethane (C2H6), helium (He), or a mixture of helium and alkane.

[0057] Based on the above technical solution, preferably, the saturable absorber is a passive mode-locked device for realizing ultra-short pulse output, and the saturable absorber is one of a semiconductor saturable absorber mirror (SESAM), graphene, black phosphorus, and molybdenum disulfide.

[0058] Based on the above technical solution, in one preferred embodiment, the resonant cavity of the mode-locked laser is a Z-shaped folded cavity structure.In another preferred embodiment, the saturable absorber is placed between the first high reflector and the second high reflector.Further preferably, the output mirror is an output coupling mirror;the dichroic mirror is a plane mirror or a polarization prism, with a transmittance of 99% or more for pump light wavelength and a reflectivity of 99% or more for laser wavelength;and the first high reflector and the second high reflector are concave mirrors with a certain curvature and a reflectivity of 99% or more for laser wavelength.

[0059] The existing laser realizes mode-locked limit pulse width in inverse proportion to linewidth, Δτ min = 1 / Δν -3 nm), which is not conducive to obtaining ultra-short pulses.Gas lasers have a small gain linewidth, for example, the gain linewidth of a He-Ne laser is about 2×10 -3nm, thus achieving a wider pulse width. This invention broadens the absorption lines of alkali metal atoms through collisional expansion by filling with a buffer gas; typically, 1–10 atm of helium gas can be used (broadening factor, γ). Cs-He (~0.03nm / atm). For example, the stretched linewidth is 0.03nm, and the reciprocal of the linewidth is 89ps. Therefore, this invention is expected to obtain mode-locked pulses of tens or hundreds of ps. This invention will be universal and can provide theoretical support for achieving mode-locking in other alkali metals, realizing an alkali metal picosecond pulse laser with good beam quality, high efficiency, and strong amplification.

[0060] The following specific application examples will further illustrate the solution and effects of the present invention.

[0061] Example 1

[0062] like Figure 1 As shown, this embodiment provides a semiconductor-pumped cesium vapor mode-locked laser, comprising: a semiconductor pump source 1, a pump light shaping system 2, a cesium vapor cell 3, an output mirror 4, a dichroic mirror 5, a first high-reflectivity mirror 6, a second high-reflectivity mirror 7, and a saturable absorber 8; the output mirror 4, the dichroic mirror 5, the first high-reflectivity mirror 6, the second high-reflectivity mirror 7, and the saturable absorber 8 constitute the resonant cavity of the mode-locked laser. The laser beam output from the semiconductor pump source 1 passes through the pump light shaping system 2 and then enters the cesium vapor cell 3 through the dichroic mirror 5. The pulsed laser oscillates in the mode-locked resonant cavity, achieving mode-locked laser output with a wavelength of 895 nm and a pulse width on the order of tens or hundreds of picoseconds. Finally, the mode-locked pulsed laser is output from the output mirror 4.

[0063] The semiconductor pump source serves as the pump source for the semiconductor-pumped cesium vapor mode-locked laser, with a pump light center wavelength of 852.3 nm and a linewidth of 0.1 nm. The pump light shaping system 2 is a lens group; the number of focusing lenses in the lens group is ≥1. The pump light emitted from the semiconductor pump source is focused by the lens group into the cesium vapor cell. The cesium vapor cell 3 is filled with cesium vapor as the gain medium, and helium and methane as buffer gases; the gain cell is placed inside a temperature-controlled furnace; the laser wavelength is 895 nm.

[0064] The mode-locked laser's resonant cavity has a folded cavity structure; the output mirror is an output coupling mirror; the dichroic mirror is a plane mirror or polarizing prism with a transmittance of over 99% for a wavelength of 852.3 nm and a reflectance of over 99% for a wavelength of 895 nm; the first and second high-reflectivity mirrors are concave mirrors with a certain curvature and a reflectance of over 99% for a wavelength of 895 nm; the saturable absorber is placed between the first and second high-reflectivity mirrors. The saturable absorber is a transmission-type semiconductor saturable absorber with a center wavelength of 895 nm.

[0065] Example 2

[0066] Based on the above embodiment 1, further preferred embodiment 2 provides a semiconductor-pumped cesium vapor mode-locked laser, which is only different in the selection of saturable absorber 8 in structure, and the repeated part will not be repeated.

[0067] The laser beam output by the semiconductor pump source 1 passes through the pump light shaping system 2, and then is incident into the cesium vapor cell 3 from the dichroic mirror 5, the pulsed laser oscillates in the mode-locked resonant cavity, the cesium vapor mode-locked laser output is realized, the wavelength is 895nm, the pulse width is dozens of picoseconds or hundreds of picoseconds, and finally the mode-locked pulsed laser is output from the output mirror 4.

[0068] Embodiment 3

[0069] As Figure 2 shown, the semiconductor-pumped cesium vapor mode-locked laser provided in the embodiment is only different from the saturable absorber and the cavity structure from embodiment 1. The rest of the structure is the same as that of embodiment 1, and the repeated part will not be repeated.

[0070] In this embodiment, the laser beam output by the semiconductor pump source 1 passes through the pump light shaping system 2, and then is incident into the cesium vapor cell 3 from the dichroic mirror 5, the pulsed laser oscillates in the mode-locked resonant cavity, the cesium vapor mode-locked laser output is realized, the wavelength is 895nm, the pulse width is dozens of picoseconds or hundreds of picoseconds, and finally the mode-locked pulsed laser is output from the output mirror 4.

[0071] The resonant cavity of the mode-locked laser is a Z-shaped folded cavity structure; the output mirror is an output coupling mirror; the dichroic mirror is a plane mirror or a polarization prism, the transmittance of which for 852.3nm wavelength is more than 99%, and the reflectivity of which for 895nm wavelength is more than 99%; the first high-reflectivity mirror and the second high-reflectivity mirror are concave mirrors with a certain curvature, and the reflectivity of which for 895nm wavelength is more than 99%. The saturable absorber is a transmission type semiconductor saturable absorber mirror, and the center wavelength is 895nm.

[0072] In summary, in order to fill the research blank of ultra-short pulse alkali metal laser, a diode laser is used as a pump source, cesium vapor with a large gain coefficient is used as a gain medium, and a saturable absorber is used as a passive mode-locked device, so that a cesium vapor ultra-short pulse laser with higher peak power is obtained, which has the characteristics of picosecond pulse width, high peak power, high efficiency, good beam quality, good amplification, and reliable use. It has important application value and development prospect in scientific frontier, detection and elimination of space debris, industrial precision machining, laser communication and medical beauty, etc.

[0073] On the other hand, the application also provides a method for generating ultra-short pulse laser, which is realized based on the above laser, comprising:

[0074] The pump light is output by a semiconductor pump source, and the pump light has a linewidth less than or equal to 0.1 nm;

[0075] The pump light is received by a pump light shaping system and is concentrated to the middle of the cesium vapor cell;

[0076] The shaped pump laser is amplified by the cesium vapor cell to generate gain laser;

[0077] The gain laser is output after being oscillated and mode-locked by a mode-locked resonant structure, and the mode-locked resonant structure comprises:

[0078] A dichroic mirror arranged on the output light path of the pump light shaping system,

[0079] A first high-reflection mirror arranged at an angle to receive the gain laser and reflect the gain laser once,

[0080] A second high-reflection mirror arranged to receive the reflected laser of the first high-reflection mirror and reflect the laser twice,

[0081] A saturable absorber to mode-lock the gain laser into ultra-short pulse,

[0082] And an output mirror arranged on the reflected light path of the dichroic mirror.

[0083] Based on the above technical solution, preferably, the first high-reflection mirror, the second high-reflection mirror and the saturable absorber form a Z-shaped folded cavity structure; or,

[0084] The saturable absorber is arranged on the reflected light path of the first high-reflection mirror and the second high-reflection mirror.

[0085] For the embodiments of the method for generating ultra-short pulse laser, since they are corresponding to the above device embodiments, the description is relatively simple, and the relevant similarities can be seen from the above embodiments, and thus will not be described in detail here.

[0086] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that: they can still modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A semiconductor-pumped cesium vapor mode-locked laser, characterized by, Comprising: a semiconductor pump source for outputting a pump light beam, the pump source being a diode laser, the output pump light center wavelength being 852.3 nm, and the line width being less than or equal to 0.1 nm; a pump light shaping system for receiving the pump light and converging it to the middle of a cesium vapor cell; the cesium vapor cell for amplifying the shaped pump light to generate gain laser; a mode-locked resonant structure for oscillating and mode-locking the gain laser to output mode-locked laser, the mode-locked resonant structure comprising: a dichroic mirror arranged on the output light path of the pump light shaping system, the dichroic mirror being a plane mirror or a polarization prism, the transmittance of the pump light wavelength being more than 99%, and the reflectivity of the laser wavelength being more than 99%; a first high-reflectivity mirror receiving the gain laser at a certain angle and reflecting the gain laser once, a second high-reflectivity mirror receiving the reflected laser of the first high-reflectivity mirror and reflecting the laser twice, the first high-reflectivity mirror and the second high-reflectivity mirror being concave mirrors with a certain curvature and a reflectivity of the laser wavelength being more than 99%; a saturable absorber for mode-locking the gain laser into ultra-short pulse, and an output mirror arranged on the reflected light path of the dichroic mirror. The saturable absorber is arranged on the reflected light path of the first high-reflectivity mirror and the second high-reflectivity mirror, and the first high-reflectivity mirror, the second high-reflectivity mirror and the saturable absorber form a Z-shaped folded cavity structure. The pump light emitted by the semiconductor pump source is focused into the cesium vapor cell through the pump light shaping system, and after being amplified by the cesium vapor as a gain medium, it enters the mode-locked resonant structure for oscillation, and finally outputs the mode-locked laser from the output mirror. The cesium vapor cell is placed in a temperature-controlled oven, which is filled with cesium vapor and mixed with a certain amount of buffer gas, and the absorption spectrum of alkali metal atoms is collisionally broadened by filling the buffer gas, including filling 1-10 atm of helium as a buffer gas, and the broadening coefficient is 0.03 nm / atm; The saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus and molybdenum disulfide.

2. The semiconductor-pumped cesium vapor mode-locked laser of claim 1, wherein, Comprising:

3. A method of generating ultra-short pulsed laser light, implemented on the basis of the laser of claim 1, characterized in that, outputting a pump light by a semiconductor pump source, the pump light line width being less than or equal to 0.1 nm; receiving the pump light by a pump light shaping system and converging it to the middle of a cesium vapor cell; amplifying the shaped pump laser by the cesium vapor cell to generate gain laser; oscillating and mode-locking the gain laser by a mode-locked resonant structure to output mode-locked laser, the mode-locked resonant structure comprising: a dichroic mirror arranged on the output light path of the pump light shaping system, a first high-reflectivity mirror receiving the gain laser at a certain angle and reflecting the gain laser once, a second high-reflectivity mirror receiving the reflected laser of the first high-reflectivity mirror and reflecting the laser twice, a saturable absorber for mode-locking the gain laser into ultra-short pulse, and an output mirror arranged on the reflected light path of the dichroic mirror.

4. The method for generating ultra-short pulse laser according to claim 3, wherein the dichroic mirror, the first high-reflectivity mirror, the second high-reflectivity mirror, the output mirror and the saturable absorber form a Z-shaped folded cavity structure; or the saturable absorber is arranged on the reflected light path of the first high-reflectivity mirror and the second high-reflectivity mirror. ​

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