Semiconductor-pumped alkali metal mode-locked laser and method of generating alkali metal mode-locked pulsed laser

Abstract

The application provides a semiconductor-pumped alkali metal mode-locked laser and a method for generating an alkali metal mode-locked pulsed 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 a middle part of an alkali metal vapor cell; the alkali metal vapor cell for gaining the shaped pumping light to generate gain laser; and a mode-locked resonant structure for oscillating and mode-locking the gain laser to output the alkali metal mode-locked laser. The application has the characteristics of picosecond pulse width, high peak power, high efficiency, good beam quality, good amplification, reliable use and the like. The application has important application value and development prospect in scientific frontiers, detection and elimination of space debris, industrial precision machining, laser communication and medical cosmetology and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultrashort pulse, in particular to a semiconductor-pumped alkali metal mode-locked laser and a method for generating alkali metal mode-locked pulse laser. BACKGROUND

[0002] With the development of human space activities, the number of space debris is increasing, which has caused serious pollution to the space environment. In particular, in the low earth orbit, the space debris in the centimeter level is the most dangerous to spacecraft because of the difficulty of tracking and cataloging and the relatively large kinetic energy. Therefore, active removal of space debris is an inevitable choice. For the detection and elimination of space debris, pulsed laser has greater advantages than continuous laser. In particular, high-repetition-rate laser with a pulse width of picosecond and a wavelength in the atmospheric window will greatly improve the peak power of the laser, which is more conducive to high-precision detection and elimination of space debris. In addition, high-peak-power picosecond laser has important application value and development prospect in scientific frontiers, industrial precision machining, laser communication and medical cosmetology, etc.

[0003] At present, the devices for obtaining high-peak-power ultrashort pulse laser 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, titanium sapphire lasers are difficult to support high-power laser output due to their low thermal conductivity; fiber lasers are difficult to continuously improve the peak power due to the nonlinear effects and damage in the optical fiber; all-solid-state lasers are 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 rate, and many are large scientific devices, which are expensive. For example, a laser with a single pulse energy of 16.7J and a peak power of 170TW, but the repetition rate is only 0.02Hz.

[0004] At present, most semiconductor-pumped alkali metal vapor lasers (DPAL) 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, etc., 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.

[0005] The ways to obtain ultra-short pulse mainly include Q-switching and mode-locking. At present, there are few research institutions studying DPAL Q-switching, and only a few reports. For example, the literature reports that the output pulse width is 238ns and 14ns. 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 (26-30ns), which shows that the alkali metal vapor laser is not suitable for pulse energy storage type laser such as Nd:YAG (upper level lifetime ~ 230us), but is more suitable for continuous operation.

[0006] And the mode-locked mode can work in continuous mode, and the pulse width is narrower (about hundreds of picoseconds), which is two orders of magnitude smaller than the pulse width obtained by cavity emptying in the literature, which will increase the peak power by two orders of magnitude, reaching several kW. If you want to get higher peak power laser, you can use the mode-locked pulse laser as the seed light and use the power amplification scheme to further improve the pulse energy and peak power. Unfortunately, there is no report on semiconductor-pumped alkali metal mode-locked laser. SUMMARY

[0007] According to the technical problems of the high peak power ultra-short pulse alkali metal laser proposed above, a semiconductor-pumped alkali metal mode-locked laser and a method for generating alkali metal mode-locked pulse laser are provided. The present application has universality and can provide theoretical support for the mode-locking of other alkali metals, and realizes a good beam quality, high efficiency and strong amplification alkali metal picosecond pulse laser.

[0008] The technical means adopted by the present application are as follows:

[0009] In one aspect, the present application provides a semiconductor-pumped alkali metal mode-locked laser, comprising:

[0010] A semiconductor pump source for outputting a pump beam;

[0011] A pump light shaping system for receiving the pump light and converging it to the middle of the alkali metal vapor cell;

[0012] An alkali metal vapor cell for gain of the shaped pump light to generate gain laser;

[0013] A mode-locked resonant structure for oscillating and mode-locking the gain laser to output alkali metal mode-locked laser;

[0014] The pump light emitted by the semiconductor pump source is focused into the alkali metal vapor cell through the pump light shaping system, and after gain by the alkali metal vapor as the gain medium, it enters the mode-locked resonant structure to form the alkali metal mode-locked laser.

[0015] Based on the above technical scheme, preferably, the mode-locked resonant structure comprises:

[0016] A dichroic mirror arranged on the output light path of the pump light shaping system;

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

[0018] A first high-reflection mirror arranged on the output light path of the alkali metal vapor cell;

[0019] A second high-reflection mirror arranged on the reflected light path of the first high-reflection mirror; and

[0020] A saturable absorber arranged on the reflected light path of the second high-reflection mirror;

[0021] The dichroic mirror, the output mirror, the first high-reflection mirror, the second high-reflection mirror, and the saturable absorber form a Z-shaped folded cavity structure.

[0022] Based on the above technical scheme, preferably, the saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus, and molybdenum disulfide.

[0023] Based on the above technical scheme, preferably, the output mirror is an output coupling mirror.

[0024] The dichroic mirror is a plane mirror or a polarizing prism, and has a transmittance of 99% or more for the pump light wavelength and a reflectivity of 99% or more for the laser wavelength.

[0025] The first high-reflection mirror and the second high-reflection mirror are concave mirrors with a certain curvature and a reflectivity of 99% or more for the laser wavelength.

[0026] Based on the above technical scheme, preferably, the pump light has a linewidth of less than or equal to 0.1 nm.

[0027] Based on the above technical scheme, preferably, the alkali metal vapor cell is placed in a temperature-controlled furnace, which is filled with rubidium or potassium vapor as a gain medium, and mixed with a certain amount of buffer gas, which is one of methane, ethane, and helium, or a mixture of helium and alkane.

[0028] On the other hand, the application also provides a method for generating an alkali metal mode-locked pulsed laser, which is implemented based on the above device and comprises:

[0029] Outputting pump light through a semiconductor pump source, the pump light having a linewidth of less than or equal to 0.1 nm;

[0030] Converging the pump light to the middle part of the alkali metal vapor cell through a pump light shaping system;

[0031] The shaped pump laser is subjected to gain by an alkali metal vapor cell to generate gain laser;

[0032] The gain laser is subjected to oscillation mode locking by a mode locking resonant structure to output alkali metal mode locked laser.

[0033] Based on the above technical scheme, preferably, the mode locking resonant structure comprises:

[0034] A dichroic mirror arranged on an output light path of the pump light shaping system;

[0035] An output mirror arranged on a reflected light path of the dichroic mirror;

[0036] A first high reflectivity mirror arranged on an output light path of the alkali metal vapor cell;

[0037] A second high reflectivity mirror arranged on a reflected light path of the first high reflectivity mirror; and

[0038] A saturable absorber arranged on a reflected light path of the second high reflectivity mirror;

[0039] The dichroic mirror, the output mirror, the first high reflectivity mirror, the second high reflectivity mirror and the saturable absorber constitute a Z-shaped folded cavity structure.

[0040] Based on the above technical scheme, preferably, the saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus and molybdenum disulfide.

[0041] Based on the above technical scheme, preferably, the output mirror is an output coupling mirror.

[0042] The dichroic mirror is a plane mirror or a polarizing prism, and the transmittance of the pump light wavelength is above 99%, and the reflectivity of the laser wavelength is above 99%.

[0043] The first high reflectivity mirror and the second high reflectivity mirror are concave mirrors with a certain curvature and a reflectivity of the laser wavelength above 99%.

[0044] Compared with the prior art, the present application has the following advantages:

[0045] 1. The laser provided by the present application has universality, can provide theoretical support for mode locking of other alkali metals, and realizes an alkali metal picosecond pulse laser with good beam quality, high efficiency and strong amplification.

[0046] 2, The application fills the research blank of the ultra-short pulse alkali metal laser, adopts a diode laser as a pumping source, an alkali metal with a large gain coefficient as a gain medium, and a saturable absorber as a passive mode-locked device, obtains an alkali metal ultra-short pulse laser with higher peak power, and 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 cosmetology.

[0047] Based on the above reasons, the application can be widely popularized in the fields of detection and elimination of space debris, industrial precision machining, laser communication and medical cosmetology. BRIEF DESCRIPTION OF DRAWINGS

[0048] 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 the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0049] Figure 1 The semiconductor-pumped alkali metal mode-locked laser provided for the embodiment 1 and the embodiment 2 of the present application.

[0050] Figure 2 The semiconductor-pumped alkali metal mode-locked laser provided for the embodiment 3 of the present application.

[0051] In the figure: 1, semiconductor pumping source; 2, pump light shaping system; 3, rubidium vapor cell / potassium vapor cell; 4, output mirror; 5, dichroic mirror; 6, first high-reflectivity mirror; 7, second high-reflectivity mirror; 8, saturable absorber. DETAILED DESCRIPTION

[0052] 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 drawings and in combination with the embodiments.

[0053] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions 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, 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 belong to the scope of protection of the present application.

[0054] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0055] The relative arrangement of components and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the application unless otherwise specifically stated. It is also to be understood that the specific dimensions shown in the drawings are not to scale, and that the dimensions of the various parts shown in the drawings are intended to be illustrative only. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail, but are to be considered part of the specification, where appropriate. In all examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as a limitation on the scope of the example embodiments. Thus, other example embodiments of the example embodiments can have different values. It is noted that like references and designations can indicate like items in the drawings, and once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0056] 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", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Without the opposite indication, these orientation words do not indicate and imply that the indicated device or element 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 each component.

[0057] For the purposes of the description, relative terms such as "on", "above", "upper surface", "upward", and the like can be used to describe one device or feature's spatial or topological relation to other devices or features as illustrated in the figures. It is to be understood that the spatial or topological terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device is inverted, then an element described as "above" or "upward" of other elements would then be oriented "below" or "downward" relative to the other elements. Accordingly, the exemplary term "above" can encompass both an "above" and "below" position. The elements can also be oriented in other ways (rotated 90 degrees or at other orientations) and the spatial or topological descriptions used herein interpreted accordingly.

[0058] In addition, it should be noted that the use of "first", "second", and the like words of distinction do not have a special meaning and are used only to distinguish between the corresponding parts, and therefore cannot be understood as limiting the scope of protection of the present application.

[0059] The application provides a semiconductor-pumped alkali metal mode-locked laser, comprising: a semiconductor pump source, a pump light shaping system, an alkali metal vapor cell, an output mirror, a dichroic mirror, a first high-reflection mirror, a second high-reflection mirror and a saturable absorber. The output mirror, the dichroic mirror, the first high-reflection mirror, the second high-reflection mirror and the saturable absorber constitute a mode-locked resonant structure. The laser beam output by the semiconductor pump source is incident into the alkali metal vapor cell from the dichroic mirror after passing through the pump light shaping system, and the pulsed laser oscillates in the mode-locked resonant cavity to realize alkali metal mode-locked laser output, the pulse width is picosecond order, and finally the mode-locked pulsed laser is output from the output mirror.

[0060] Based on the above technical scheme, preferably, the semiconductor pump source and the pump light shaping system can refer to the scheme described in the document "Brewster angle structure 16.8W semiconductor-pumped rubidium vapor laser" (China Laser, 43(3), 2016), and details are not repeated here. Further, the pump light shaping system is a lens group, and the number of lenses in the lens group is greater than or equal to 1. The pump light emitted by the semiconductor pump source is focused into the alkali metal vapor cell through the lens group. The semiconductor pump source serves as a pump source of the semiconductor-pumped alkali metal mode-locked laser, and the line width is less than or equal to 0.1 nm.

[0061] Based on the above technical scheme, the alkali metal vapor cell is placed in a temperature-controlled furnace, and the inside is filled with rubidium or potassium vapor as a gain medium and a certain amount of buffer gas. Preferably, the buffer gas is one of methane (CH4), ethane (C2H6), helium (He), or a mixed gas of helium and alkane.

[0062] Based on the above technical solutions, preferably, the mode-locked resonant structure includes: a dichroic mirror disposed on the output optical path of the pump light shaping system; an output mirror disposed on the reflection optical path of the dichroic mirror; a first high-reflectivity mirror disposed on the output optical path of the alkali metal vapor cell; a second high-reflectivity mirror disposed on the reflection optical path of the first high-reflectivity mirror; and a saturable absorber disposed on the reflection optical path of the second high-reflectivity mirror; the dichroic mirror, the output mirror, the first high-reflectivity mirror, the second high-reflectivity mirror, and the saturable absorber constitute a Z-shaped folded cavity structure. More preferably, the output mirror is an output coupling mirror; the dichroic mirror is a plane mirror or a polarizing prism with a transmittance of over 99% for the pump light wavelength and a reflectance of over 99% for the laser wavelength; the first and second high-reflectivity mirrors are concave mirrors with a certain curvature and a reflectance of over 99% for the laser wavelength.

[0063] Based on the above technical solutions, preferably, the saturable absorber is a passive mode-locked device that enables ultra-short pulse output, and the saturable absorber is one of semiconductor saturable absorber mirrors (SESAM), graphene, black phosphorus, molybdenum disulfide, etc.

[0064] The limiting pulse width for mode-locking in existing lasers is inversely proportional to the linewidth, Δτ. min =1 / Δν g It is evident that the wider the gain linewidth, the more likely a narrow mode-locked pulse width can be obtained. However, the Doppler linewidth of alkali metal atoms is extremely narrow (1–2 × 10⁻⁶). -3 This (nm) limitation is detrimental to obtaining ultrashort pulses. Gas lasers have relatively small gain linewidths; for example, the gain linewidth of a He-Ne laser is approximately 2 × 10⁻⁶. -3 nm, thus it achieves a wider pulse width. In this invention, the absorption lines of alkali metal atoms are broadened by collision by filling with a buffer gas. Typically, 1–10 atm of helium gas can be filled (broadening factor, γ). Rb-He ~0.03nm / atm, γ K-He (~0.02nm / atm). For example, the stretched linewidth is 0.03nm, and the reciprocal of the linewidth is 70ps. Therefore, this invention is expected to obtain mode-locking pulses of tens or hundreds of ps.

[0065] The following specific application examples will further illustrate the solution and effects of the present invention.

[0066] Example 1

[0067] like Figure 1As shown, the semiconductor-pumped alkali metal mode-locked laser provided by the embodiment comprises a semiconductor pump source 1, a pump light shaping system 2, a rubidium vapor cell 3, an output mirror 4, a dichroic mirror 5, a first high-reflection mirror 6, a second high-reflection mirror 7, and a saturable absorber 8; the output mirror 4, the dichroic mirror 5, the first high-reflection mirror 6, the second high-reflection mirror 7, and the saturable absorber 8 constitute a mode-locked laser resonant cavity structure. The laser beam output by the semiconductor pump source 1 is incident into the rubidium vapor cell 3 from the dichroic mirror 5 after passing through the pump light shaping system 2, and the pulsed laser oscillates in the mode-locked resonant cavity to realize rubidium vapor mode-locked laser output, with a wavelength of 795 nm and a pulse width of tens of picoseconds or hundreds of picoseconds, and finally the mode-locked pulsed laser is output from the output mirror 4.

[0068] The semiconductor pump source 1 is used as the pump source of the semiconductor-pumped rubidium vapor mode-locked laser, with a pump light center wavelength of 780.2 nm and a line width of 0.1 nm. The pump light shaping system 2 is a lens group; the number of focusing lenses in the lens group is greater than or equal to 1; and the pump light emitted by the semiconductor pump source 1 is focused into the rubidium vapor cell 3 through the lens group. The rubidium vapor cell 3 is filled with rubidium vapor as a gain medium and filled with helium and methane as buffer gas; the gain cell is placed in a temperature control furnace; and the laser wavelength is 795 nm.

[0069] In addition, the mode-locked resonant structure of the mode-locked laser comprises a Z-shaped folded cavity. The output mirror 4 is an output coupling mirror; the dichroic mirror 5 is a plane mirror with a transmittance of 99% or more for a wavelength of 780.2 nm and a reflectivity of 99% or more for a wavelength of 795 nm; the first high-reflection mirror 6 and the second high-reflection mirror 7 are concave mirrors with a certain curvature and a reflectivity of 99% or more for a wavelength of 795 nm. The saturable absorber 8 is a semiconductor saturable absorber mirror with a center wavelength of 795 nm.

[0070] Embodiment 2

[0071] Based on the above-mentioned embodiment 1, a further preferred embodiment 2 provides a semiconductor-pumped alkali metal mode-locked laser, which is only different in the selection of the saturable absorber 8 in structure, and the repeated parts are not described again. In this embodiment, the saturable absorber 8 is a black phosphorus saturable absorber.

[0072] The laser beam output by the semiconductor pump source 1 is incident into the rubidium vapor cell 3 from the dichroic mirror 5 after passing through the pump light shaping system 2, and the pulsed laser oscillates in the mode-locked resonant cavity to realize rubidium vapor mode-locked laser output, with a wavelength of 795 nm and a pulse width of tens of picoseconds or hundreds of picoseconds, and finally the mode-locked pulsed laser is output from the output mirror 4.

[0073] Embodiment 3

[0074] The third embodiment of the present application is as follows Figure 2As shown, the semiconductor-pumped alkali metal mode-locked laser is only different from the embodiment 1 in that the semiconductor pump source 1, the potassium vapor cell 3, the dichroic mirror 5 and the laser wavelength, and the rest of the structure is the same as the embodiment 1, and the repeated part will not be described again.

[0075] In this embodiment, the alkali metal vapor is potassium (K), and the laser wavelength is 770 nm. The semiconductor pump source 1 is used as the pump source of the alkali metal mode-locked laser, the pump light center wavelength is 766.7 nm, and the line width is 0.1 nm. The saturable absorber 8 is a semiconductor saturable absorber mirror, and the center wavelength is 770 nm.

[0076] The resonant cavity of the mode-locked laser is a Z-shaped folded cavity structure; the dichroic mirror 5 is a polarization prism, and the transmittance for a wavelength of 766.7 nm is more than 99%, and the reflectivity for a wavelength of 770 nm is more than 99%; the first high-reflectivity mirror 6 and the second high-reflectivity mirror 7 are concave mirrors with a certain curvature, and the reflectivity for a wavelength of 770 nm is more than 99%.

[0077] The laser beam output by the semiconductor pump source 1 is incident into the potassium vapor cell 3 from the dichroic mirror 5 after passing through the pump light shaping system 2, and the pulse laser oscillates in the mode-locked resonant cavity to realize potassium vapor mode-locked laser output, with a wavelength of 770 nm.

[0078] Since the potassium vapor cell can realize broadening by adding only helium, a relatively high pressure can be added, the line width will be wider than that of rubidium vapor and cesium vapor, and therefore the pulse width obtained is also narrower, and it is expected to realize a pulse width of ten picoseconds or tens of picoseconds, and finally the mode-locked pulse laser is output from the output mirror 4.

[0079] On the other hand, the present application also provides a method for generating an alkali metal mode-locked pulse laser, which is realized based on the above device, comprising:

[0080] Outputting pump light by a semiconductor pump source, wherein the pump light has a line width less than or equal to 0.1 nm;

[0081] Converging the pump light to the middle part of the alkali metal vapor cell by a pump light shaping system;

[0082] Generating gain laser by the alkali metal vapor cell to the shaped pump laser;

[0083] Outputting alkali metal mode-locked laser after oscillating and mode-locking the gain laser by a mode-locked resonant structure.

[0084] Based on the above technical solution, preferably, the mode-locked resonant structure comprises:

[0085] A dichroic mirror arranged on the output light path of the pump light shaping system;

[0086] An output mirror arranged on the reflected light path of the dichroic mirror;

[0087] a first high-reflectivity mirror arranged on the light path of the alkali metal vapor cell output;

[0088] a second high-reflectivity mirror arranged on the light path of the first high-reflectivity mirror reflection;

[0089] a saturable absorber arranged on the light path of the second high-reflectivity mirror reflection;

[0090] The dichroic mirror, the output mirror, the first high-reflectivity mirror, the second high-reflectivity mirror and the saturable absorber form a Z-shaped folded cavity structure.

[0091] Based on the above technical solution, preferably, the saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus and molybdenum disulfide.

[0092] Based on the above technical solution, preferably, the output mirror is an output coupling mirror.

[0093] The dichroic mirror is a plane mirror or a polarizing prism, and the transmittance of the dichroic mirror to the pump light wavelength is greater than 99%, and the reflectivity of the dichroic mirror to the laser light wavelength is greater than 99%.

[0094] The first high-reflectivity mirror and the second high-reflectivity mirror are concave mirrors with a certain curvature, and the reflectivity of the concave mirrors to the laser light wavelength is greater than 99%.

[0095] For the embodiments of the alkali metal mode-locked pulse laser generation method of the present application, since they are corresponding to the above device embodiments, the description is relatively simple, and the relevant similarities can be seen from the above embodiment descriptions, and thus will not be described in detail here.

[0096] 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 to 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 alkali mode-locked laser, characterized by comprising: The semiconductor pumping source is used to output a pumping light beam, the pumping light center wavelength is 780.2 nm, and the line width is 0.1 nm. The pumping light shaping system is used to receive the pumping light and converge the pumping light to the middle part of the alkali metal vapor cell. The mode-locked resonant structure is used to oscillate and mode-lock the gain laser to output the alkali metal mode-locked laser. The alkali metal vapor cell is internally filled with rubidium or potassium vapor as gain medium, and the absorption spectral line of alkali metal atom is collisionally broadened by filling buffer gas, which is used to gain the shaped pump light to generate gain laser, including filling 1-10 atm of helium as buffer gas, when the gain medium is rubidium vapor, the broadening coefficient is 0.03 nm / atm, when the gain medium is potassium vapor, the broadening coefficient is 0.02 nm / atm. The pumping light emitted by the semiconductor pumping source is focused into the pumping light shaping system, enters the alkali metal vapor cell as the gain medium, and then enters the mode-locked resonant structure to generate the alkali metal mode-locked laser. The mode-locked resonant structure comprises:

2. The semiconductor-pumped alkali mode-locked laser of claim 1, wherein, A dichroic mirror arranged on the output light path of the pumping light shaping system; An output mirror arranged on the reflected light path of the dichroic mirror; A first high-reflection mirror arranged on the output light path of the alkali metal vapor cell; A second high-reflection mirror arranged on the reflected light path of the first high-reflection mirror; and A saturable absorber arranged on the reflected light path of the second high-reflection mirror. The dichroic mirror, the output mirror, the first high-reflection mirror, the second high-reflection mirror and the saturable absorber form a Z-shaped folded cavity structure. The saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus and molybdenum disulfide.

3. The semiconductor-pumped alkali mode-locked laser of claim 2, wherein, The output mirror is an output coupling mirror.

4. The semiconductor-pumped alkali mode-locked laser of claim 2, wherein, The dichroic mirror is a plane mirror or a polarization prism, the transmittance of the dichroic mirror to the pumping light wavelength is greater than 99%, and the reflectivity of the dichroic mirror to the laser wavelength is greater than 99%. The first high-reflection mirror and the second high-reflection mirror are concave mirrors with a certain curvature, and the reflectivity of the first high-reflection mirror and the second high-reflection mirror to the laser wavelength is greater than 99%. The line width of the pumping light is less than or equal to 0.1 nm.

5. The semiconductor-pumped alkali mode-locked laser of claim 1, wherein, The semiconductor pumping source is used to output a pumping light, the line width of the pumping light is less than or equal to 0.1 nm; 6. A method of generating an alkali metal mode-locked pulsed laser, implemented based on the semiconductor-pumped alkali metal mode-locked laser of claim 1, characterized in that, The pumping light shaping system is used to receive the pumping light and converge the pumping light to the middle part of the alkali metal vapor cell; The alkali metal vapor cell is used to gain the shaped pumping laser to generate a gain laser; The mode-locked resonant structure is used to oscillate and mode-lock the gain laser to output the alkali metal mode-locked laser. The mode-locked resonant structure comprises: A dichroic mirror arranged on the output light path of the pumping light shaping system; 7. The method of generating an alkali metal mode-locked pulsed laser according to claim 6, wherein, An output mirror arranged on the reflected light path of the dichroic mirror; A first high-reflection mirror arranged on the output light path of the alkali metal vapor cell; A second high-reflection mirror arranged on the reflected light path of the first high-reflection mirror; and A saturable absorber arranged on the reflected light path of the second high-reflection mirror. The dichroic mirror, the output mirror, the first high-reflection mirror, the second high-reflection mirror and the saturable absorber form a Z-shaped folded cavity structure. The saturable absorber is one of a semiconductor saturable absorber mirror, graphene, black phosphorus and molybdenum disulfide. The output mirror is an output coupling mirror.

8. The method of generating an alkali metal mode-locked pulsed laser according to claim 7, wherein, The dichroic mirror is a plane mirror or a polarization prism, the transmittance of the dichroic mirror to the pumping light wavelength is greater than 99%, and the reflectivity of the dichroic mirror to the laser wavelength is greater than 99%.

9. The method of generating an alkali metal mode-locked pulsed laser of claim 7, wherein, The first high-reflection mirror and the second high-reflection mirror are concave mirrors with a certain curvature, and the reflectivity of the first high-reflection mirror and the second high-reflection mirror to the laser wavelength is greater than 99%. ​ ​

Images