CN112234421B - Single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser and working method - Google Patents

Single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser and working method Download PDF

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CN112234421B
CN112234421B CN202011055545.4A CN202011055545A CN112234421B CN 112234421 B CN112234421 B CN 112234421B CN 202011055545 A CN202011055545 A CN 202011055545A CN 112234421 B CN112234421 B CN 112234421B
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laser
walled carbon
carbon nanotube
mirror
chiral
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CN112234421A (en
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刘善德
崔娜
赵雨晴
陈波
张宁
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Shandong University of Science and Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/0915—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light
    • H01S3/0933—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light of a semiconductor, e.g. light emitting diode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08059—Constructional details of the reflector, e.g. shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1106—Mode locking
    • H01S3/1112—Passive mode locking
    • H01S3/1115—Passive mode locking using intracavity saturable absorbers
    • H01S3/1118—Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based

Abstract

The invention relates to the technical field of laser, and provides a single-chiral (7, 5) single-walled carbon nanotube saturated absorption red light pulse solid laser and a working method thereof, wherein the red light pulse solid laser consists of a semiconductor laser diode pumping source, a light focusing coupling system, a laser resonant cavity, a laser gain medium and a Q modulator, wherein the semiconductor laser diode pumping source is a GaN blue light diode, and the laser gain medium is a Pr (positive) laser gain medium3+YLF crystal, Q modulation device is single chirality (7, 5) single-wall carbon nano tube saturated absorber, corresponding absorption peak is at 640 nm. In the technical field of laser display, compared with the traditional 1.3 mu m frequency doubling red laser, the red pulse solid-state laser has the advantages of simple and compact structure, stable and efficient output, low cost, easiness in miniaturization and convenience and the like.

Description

Single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser and working method
Technical Field
The invention relates to the technical field of laser, in particular to a single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser and a working method thereof.
Background
The laser display technology has the advantages of high color purity, flexible and changeable display picture size, wide color gamut, no harmful electromagnetic radiation and the like, and is widely applied to a plurality of fields of digital cinema, large public information screens, teaching demonstration, virtual reality simulation and the like. The three-primary-color laser is a key part of the laser display technology and becomes a research hotspot in the technical field of laser. Compared with the mature green laser and the blue laser with smaller power requirement, the red laser with high stability, compact structure and high power becomes the key point of research. The most common conventional way to generate red laser light is a 1.3 μm frequency doubled laser: pumping neodymium-doped crystal (Na: YAG, Nd: YVO) by using laser diode4、Nd:YAP、Nd:GdVO4Etc.) to generate 1.3 mu m wave band fundamental frequency light, and then utilizing LBO, KTP nonlinear crystal or PPLN, PPLT and other optical superlattice materials to make 1.3 mu m fundamental frequency light enterAnd performing frequency doubling to obtain red light laser output with the central wavelength of 670 nm. Although the laser material of the near infrared band is mature compared with the pumping technology, the output efficiency of the mode is still limited by the nonlinear crystal material, the requirements on the coating, the cutting process and the like of the nonlinear crystal material are high, the frequency doubling process is easily influenced by a plurality of factors such as experimental environment, crystal cut angle, laser line width and the like, and the high stability is not achieved; in addition, the frequency doubling laser has a complicated and bulky structure and high cost, which is not favorable for miniaturization and commercialization.
In 2004, a.rchter and e.heumann first used GaN Laser Diode (LD) pumped Pr with a center wavelength of 442nm3+YLF crystal, the red laser output of 639.7nm is obtained, and the efficiency reaches 24 percent. At the time, the output power of the GaN diode is only 25mW, so that the final output power is only 1.8 mW. GaN laser diode and Pr3+Good gain-bandwidth matching of YLF crystals leads to high energy conversion efficiency of the laser. In recent years, GaN blue laser diodes are rapidly developed, the output power of the GaN blue laser diodes can reach 5W at most, and a Pr-doped ion crystal all-solid-state laser directly pumped by a GaN blue LD is rapidly developed, so that the all-solid-state laser has the advantages of few structural units, compact structure, low cost, high energy conversion efficiency, high output stability, excellent spot quality and the like. Continuous red light all-solid-state lasers are becoming more mature nowadays, but in the pursuit of more stable and higher optical power density red lasers, the search for red lasers has turned to red pulse laser research. The passive Q modulation mode is one of the important methods for realizing a pulse laser, and compared with the active Q modulation mode, the passive Q modulation mode is widely used because of its advantages of simple and compact structure, no need of external circuits and plug-ins, low cost, easy generation of high stability and high power pulse laser. The Q modulation device is used as a core component of a passive Q modulation mode, and directly influences the output performance of pulse laser, so that the search for a Q modulation material with excellent photoelectric characteristics, such as high third-order nonlinear coefficient, high carrier mobility rate, ultra-fast relaxation time and the like, is always a hot spot in the technical field of laser.
Carbon is used as a source of the earth's life,as a skeleton element constituting all organic life bodies, it has various electron orbital characteristics (SP, SP)2，SP3Orbital hybridization) with SP2The orbital anisotropy makes allotropes containing carbon as the only element have structural anisotropy and diverse properties. In addition, the non-toxic and harmless properties of carbon materials to human bodies make them always popular with researchers. In 2004, two England scientists successfully prepare a novel two-dimensional carbon material graphene by using a mechanical stripping method, and the graphene becomes a star material in various fields by virtue of excellent optical, electrical, thermodynamic and other characteristics of the graphene. The graphene has the characteristics of ultra-wide spectrum optical response, ultra-high carrier mobility, ultra-fast carrier recovery time and the like, shows the potential of the graphene serving as an optical modulation material, and is rapidly and successfully applied to a red pulse laser. However, the weak absorption in the red band due to the broad spectral absorption limits the output of high power red pulsed lasers.
The low-dimensional material single-wall carbon nanotube is used as a graphene-like carbon material and can be regarded as a one-dimensional seamless hollow cylindrical nanotube formed by curling single-layer graphene, and has the same basic structural unit as graphene, namely SP2The single-walled carbon nanotube has excellent characteristics similar to graphene, such as extremely high carrier mobility, subpicosecond relaxation time, higher third-order nonlinear coefficient, low saturation flux and the like; in addition, the single-walled carbon tube has unique one-dimensional structure, excellent thermodynamic stability and high thermal conductivity, which make the single-walled carbon tube become a hot nano material for the light modulation device. Actually, the single-walled carbon nanotube has been discovered by Lijima, a japanese scientist, as early as 1993, and is limited by the immature preparation process at that time, the prepared single-walled carbon nanotube has disordered chirality and large tube diameter distribution range, which causes the defects of wide spectral absorption and weak saturation absorption of a specific wave band, and limits the further application of the single-walled carbon nanotube in a pulse laser. With the rapid development of preparation technology and technology in recent years, the problems of inconsistent electronic structure, structural difference of energy band and the like brought by the multi-chiral single-walled carbon tube are being solved one by one, and the preparation of high-quality single-chiral single-walled carbon nanotubes is getting more and moreThe easier it is. The single-walled carbon nanotube with single chirality not only greatly improves the carrier mobility (>105cm2·V-1·s-1) And an extremely narrow absorption waveband is provided, the loss caused by the absorption waveband is reduced, and the saturated absorption of the absorption waveband is improved. And based on the relation between chirality and carbon tube bandwidth, the single-walled carbon nanotube with high absorption for specific wave band can be customized. These above clearly indicate that the single-chiral single-walled carbon nanotube is an ideal Q-modulating material in a red-pulsed laser.
Disclosure of Invention
Based on the above background, the present invention aims to solve the technical problems of complex structure, large system and low stability of the current red light pulse laser, and provides a red light pulse all-solid-state laser and a working method thereof, which realize high stability and simple and compact structure based on saturation absorption of a single-walled carbon nanotube made of a low-dimensional material, so as to promote further development of visible pulse solid-state lasers.
Description of terms:
Pr3+YLF crystal, praseodymium-doped lithium yttrium fluoride crystal, its molecular formula is Pr3+:LiYF4；
YAG, Yttrium aluminum garnet, with formula Y3Al5O12；
AR: anti-reflection, the light transmittance to certain wavelength is not less than 99.8%;
AR @430-490 nm: the general abbreviation of the 430-490nm waveband antireflection film;
HT: high transmittance, and the light transmittance to certain wavelength is not lower than 99.5%;
HR: high reflectivity, and light reflectivity of not less than 99.8% for certain wavelength.
In order to achieve the aim 1, the invention adopts the following technical scheme:
a single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser comprises a semiconductor laser diode pumping source, a light focusing coupling system, a laser gain medium, a laser resonant cavity and a Q modulation device, and is characterized in that the semiconductor laser diode pumping source, the light focusing coupling system and the laser resonant cavity are sequentially arranged; the laser resonant cavity comprises an input mirror and a coupling output mirror, the input mirror and the coupling output mirror are respectively arranged at two ends of a laser gain medium, a Q modulation device is inserted into the laser resonant cavity and is tightly attached to the back of the laser gain medium, and the laser gain medium and the Q modulation device are sequentially arranged in the laser resonant cavity according to the direction of a light path; the light focusing coupling system comprises a plano-concave cylindrical mirror, a plano-convex cylindrical mirror and a plano-convex focusing lens which are sequentially arranged.
Preferably, the laser gain medium is Pr3+YLF crystal.
Preferably, the Q modulation device is a single-walled carbon nanotube saturable absorber, chiral controlled growth is realized by a chemical vapor deposition method, the chirality is (7, 5), the corresponding absorption peak is at 640nm, the corresponding pipe diameter is small, the distribution range is 0.79-0.92nm, and based on the advantage of single chirality, the single-walled carbon nanotube not only improves the carrier mobility (the carrier mobility)>105cm2·V-1·s-1) The saturation absorption for the 640nm laser is also enhanced.
Preferably, the single-chiral (7, 5) single-walled carbon nanotube saturable absorber is prepared by spin coating a single-walled carbon nanotube solution which is grown by manual control on a YAG or quartz substrate, wherein the light passing surface of the YAG or quartz substrate is square, and the side length range of the square is 1-5 mm.
Preferably, the semiconductor laser diode pump source is a GaN blue diode pump source.
Preferably, the output power of the GaN blue light diode pump source is 0-3.5W, the output wavelength is 440-446nm, and the center wavelength is 442nm, so as to provide the pump energy for the laser gain medium, since Pr is3+The YLF crystal is a positive uniaxial crystal and is cut along the optical a-axis, so that the crystal has polarization absorption characteristic, and further preferably has a GaN blue light diode pump source with polarization characteristic, so that Pr is used as the pump source3 +The YLF crystal absorbs the pumping energy more fully, and the efficiency of the laser is increased.
Preferably, the focal length of the light focusing coupling system is 25-75mm, and the pump light is shaped and focused on the laser gain medium.
Preferably, Pr3+YLF crystalThe trivalent praseodymium ion doping concentration of the body is 0.5 at%, the cutting processing is carried out along the crystallographic a axis, and the size of the light passing surface is 5 x 5mm2，4*4mm2，3*3mm2Or 2 x 2mm2The length of the light passing direction is 2-10 mm.
Preferably, the laser resonant cavity is a straight resonant cavity, and the cavity length distribution is 2-100 mm.
Preferably, the input mirror in the laser resonant cavity is a plane mirror, the input surface is plated with AR @ 430-; the coupling output mirror in the laser resonant cavity is a plane mirror or a plano-concave mirror, the laser cavity surface of the coupling output mirror is plated with PR @ 550-.
Preferably, the input mirror and the coupling-out mirror are further simplified to Pr3+Two end faces of YLF crystal are respectively plated with optical films with the same transmittance to achieve the function of frequency selection. Furthermore, before crystal coating, the prepared single-walled carbon nanotube solution is coated on the crystal output surface in a spinning mode, and then a corresponding optical thin film is coated, so that the length of the laser resonant cavity is further compressed to be the same as that of the laser gain medium, the red light pulse laser is more miniaturized and convenient, and the laser pulse laser has advantages in application fields such as laser display and the like.
In order to achieve the aim 2, the invention adopts the following technical scheme:
blue pump light emitted by a GaN blue light diode pump source is focused to a laser gain medium Pr through a light focusing coupling system3+On a YLF crystal, coupling output mirrors with different transmittances are utilized to respectively build up a laser resonance straight cavity, and the output characteristics of continuous laser are researched under different transmittances;
based on the continuous laser resonant cavity, inserting a single-chiral (7, 5) single-walled carbon nanotube saturable absorber into the laser resonant cavity, tightly attaching the saturable absorber to a laser gain medium, and adjusting the position and the angle of the saturable absorber; due to the saturated absorption characteristic of the single-chiral (7, 5) single-walled carbon nanotube saturable absorber, the Q value of the quality factor of the laser resonant cavity is adjusted to be low, and laser cannot oscillate; under this kind of state, the pumping light that continues to increase, the internal reversal particle number of laser resonator constantly accumulates, after accumulating to a certain extent, the absorption of single chirality (7, 5) single-walled carbon nanotube saturable absorber to ruddiness laser reduces suddenly, and the Q value is increaseed rapidly, and the intracavity particle number density is obviously higher than threshold value reversal particle number density, forms laser oscillation to the reversal particle number is consumed completely rapidly in the short time, realizes ruddiness pulse laser's stable output.
The invention has the following beneficial technical effects:
(1) the laser adopts a GaN blue LD direct pumping mode. The output center wavelength of LD is 442nm, and the gain medium Pr3+The absorption center wavelength of the YLF crystal meets the gain bandwidth matching, and the energy conversion efficiency of the laser is improved.
(2) The laser adopts a passive Q modulation mode. Compared with an active Q modulation mode, the passive Q modulation mode does not need complex structures such as a high voltage, an electro-optic driver or a radio frequency modulator, and only needs to select a proper saturable absorber as a Q modulation device, so that the red light pulse laser has the advantages of simple and compact structure, simple design and low cost.
(3) The laser adopts a single-chiral (7, 5) single-walled carbon nanotube saturable absorber as a Q modulation device material. The single-chiral (7, 5) single-walled carbon nanotube saturable absorber grows through chiral control of a chemical vapor deposition method, and the characteristic of the single chirality is benefited, so that the transmission efficiency of current carriers in the single-walled carbon tube is greatly improved, the energy band structure tends to be uniform, the carbon tube has extremely narrow absorption bandwidth and extremely strong saturable absorption at the 640nm absorption peak, the loss of the single-walled carbon tube saturable absorber is greatly reduced, and the red light pulse laser output with high stability and high light beam quality is realized.
(4) The present invention uses a plano-concave or straight resonant cavity. Further simplified to laser gain medium Pr3+Two end faces of the YLF crystal are plated with optical films which are the same as the cavity mirror to replace the cavity mirror, so that a laser resonant cavity is formed, the purpose of frequency selection is achieved, the cavity length is further compressed to the length of a laser gain medium, and the red light pulse laser is more miniaturized and more convenient.
Drawings
FIG. 1 is a schematic structural diagram of a red light pulse laser saturated and absorbed by a single-chiral single-walled carbon nanotube;
wherein, 1 is GaN blue light diode pumping source, 2 is light focusing coupling system, 3 is input mirror, 4 is Pr3+YLF crystal, 5 is a single-chiral (7, 5) single-walled carbon nanotube saturable absorber, 6 is a coupling output mirror;
FIG. 2 is a schematic diagram of a single-walled carbon nanotube saturable absorber structure;
wherein 7 is a single-wall carbon nanotube sodium deoxycholate solution, and 8 is a YAG or quartz substrate;
fig. 3 is a graph (a) of variation of pulse width and repetition frequency with absorbed pump power, a graph (b) of variation of pulse energy and peak power with absorbed pump power, and a graph (c) of single pulse and pulse sequence, under a coupled output mirror with a transmittance of 5%, when red pulse laser output is realized;
fig. 4 is a graph (a) of variation of pulse width and repetition frequency with absorbed pump power, a graph (b) of variation of pulse energy and peak power with absorbed pump power, and a graph (c) of single pulse and pulse sequence, under a coupled output mirror with a transmittance of 3%, when red pulse laser output is realized;
FIG. 5 is a graph (a) showing the variation of pulse width and repetition frequency with absorbed pump power, a graph (b) showing the variation of pulse energy and peak power with pump power, and a graph (c) showing the variation of single pulse and pulse sequence, under a coupled output mirror having a transmittance of 1%;
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:
a single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser is shown in figure 1 and comprises a GaN blue light diode pumping source 1, a light focusing coupling system 2 and Pr3+YLF crystal 4, laser resonant cavity and single-chiral (7, 5) single-walled carbon nanotube saturable absorber 5, characterized by, GaN blue light diode pumping source 1, light focuses and couples the system 2, laser resonant cavity to arrange sequentially; the laser resonant cavity comprises an input mirror 3 and a coupling output mirror 6, wherein the input mirror 3 and the coupling output mirror 6 are respectively arranged on Pr3+The saturated absorber 5 of the single-chiral (7, 5) single-walled carbon nanotube is inserted into the laser resonant cavity at two ends of the YLF crystal 4 and is tightly attached to the Pr3+Behind the YLF crystal 4, Pr3+The YLF crystal 4 and the single-chiral (7, 5) single-walled carbon nanotube saturable absorber 5 are sequentially arranged in the laser resonant cavity according to the light path direction; the light focusing coupling system 2 comprises a planoconcave cylindrical mirror, a planoconvex cylindrical mirror and a planoconvex focusing lens which are sequentially arranged;
as shown in figure 2, the single-chiral (7, 5) single-walled carbon nanotube saturable absorber 5 is prepared by spin-coating a single-walled carbon nanotube deoxycholate solution 7 growing under manual control on a YAG or quartz substrate 8, wherein the light passing surface of the YAG or quartz substrate 8 is square, and the light passing surface is 1 x 1mm2The single-walled carbon nanotube sodium deoxycholate solution 7 is loaded on the YAG substrate.
Specifically, the output power of the GaN blue light diode pump source 1 is 0-3.5W, the output wavelength is 440-446nm, and the center wavelength is 442nm due to Pr3+The YLF crystal 4 is a positive uniaxial crystal and is cut along the optical a-axis, so that the crystal has polarization absorption characteristic, and further preferably a GaN blue light diode pump source with polarization characteristic is used to make Pr3+The YLF crystal 4 can absorb the pumping energy more fully and increase the energy conversion efficiency of the laser.
Specifically, the light focusing coupling system 2 is a lens group with a focal length of 25.4mm, and focuses and couples the pump light to Pr3+On YLF crystal 4, to Pr3+The size of the pumping light spot on the YLF crystal 4 meets the mode matching with the size of the Gaussian beam light spot at the position of the crystal in the laser resonant cavity.
Specifically, the laser resonant cavity is a straight resonant cavity, and the cavity length distribution is 2-100 mm; an input mirror 3 and a coupling output mirror 6 in the laser resonant cavity are both coated with films, the input mirror 3 is a plane mirror, the input surface is coated with AR @ 430-; the coupling output mirror 6 in the laser resonant cavity is a plane mirror or a planoconcave mirror, the laser cavity surface of the coupling output mirror is coated with PR @ 550-;
specifically, Pr3+The doping concentration of trivalent Pr of YLF crystal 4 is 0.5 at%, and the crystal is cut along crystallographic a-axis (i.e. light-passing direction), and the light-passing surface is 3 x 3mm2The two sides of the square respectively correspond to the b axis and the c axis of the crystallographic structure of the crystal, and the length of the light-passing direction is 7 mm.
Specifically, the single-chiral (7, 5) single-walled carbon nanotube saturable absorber 5 has a corresponding absorption peak at 640nm, a corresponding tube diameter smaller and a distribution range of 0.79-0.92nm, and based on the advantage of single chirality, the single-walled carbon nanotube not only improves the carrier mobility ((C)>105cm2·V-1·s-1) The saturation absorption for the 640nm laser is also enhanced.
Further, a working method of the single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser comprises the following steps:
first, under different transmittances (T ═ 1%, 3%, 5%), the blue pumping light generated by the GaN laser diode pumping source 1 is focused to the laser gain medium Pr through the light focusing coupling system 23+On the YLF crystal 4, a laser resonance plano-concave straight cavity is built, the length of a resonant cavity, the angle of an input mirror and the like are adjusted, and the maximum continuous laser output power under different transmittances is explored.
Secondly, under the condition of continuous laser optimal output, inserting the single-chiral (7, 5) single-walled carbon nanotube saturable absorber 5 into the cavity and clinging to Pr3+Fine-tuning the position and angle of the crystal 4 behind it. In the initial stage of laser operation, the pumping power is low, the Q value of the quality factor in the cavity is reduced due to the insertion loss caused by the single-chiral (7, 5) single-walled carbon tube saturable absorber 5, and no red light pulse laser is output; the pumping power is continuously increased, the number density of the reversed particles in the cavity is continuously increased, when the saturated light intensity is reached, the absorption of the single-chiral (7, 5) single-walled carbon tube saturable absorber 5 on the red light laser is rapidly reduced, the insertion loss is rapidly reduced, the Q value is rapidly increased, the number of the reversed particles is exhausted in a short time, the laser oscillation is rapidly established, and the output of the high-stability red light pulse laser is realized. Experiments were carried out at different transmittances (T ═ 1%, 3%, 5%) respectively, and the results were combinedThe following fruits were obtained:
(1) when the coupling output mirror 6 with the transmittance of 5% is selected, the change curve of the pulse width and the repetition frequency along with the input pumping power is shown in fig. 3(a), the pulse width is linearly reduced along with the increase of the absorbed pumping power, the repetition frequency is in an opposite trend, and the shortest pulse width is 200ns and the highest repetition frequency is 238.1 kHz; the corresponding peak power and pulse energy as a function of absorbed pump power are shown in FIG. 3(b), both increasing with increasing pump power, with a maximum peak power of 844mW and a maximum pulse energy of 169 nJ. The pulse sequence and the single pulse curve at different repetition frequencies are shown in fig. 3(c), and the graph shows that the laser outputs smooth and stable red light pulse laser.
(2) When the coupling output mirror 6 with the transmittance of 3% is selected, the curve of the pulse width and the repetition frequency along with the change of the input pumping power is shown in fig. 4(a), along with the linear increase of the absorbed pumping power, the pulse width is linearly decreased and the repetition frequency is linearly increased, and finally the obtained shortest pulse width is 240ns and the highest repetition frequency is 227.3 kHz; the corresponding peak power and pulse energy as a function of input pump power are shown in fig. 4(b), resulting in a maximum peak power of 572mW and a maximum pulse energy of 137 nJ. The pulse sequence and the single pulse curve at different repetition frequencies are shown in fig. 4(c), and the graph shows that the laser outputs smooth and stable red light pulse laser.
(3) When the coupling output mirror 6 with the transmittance of 1% is selected, the pulse width and the repetition frequency are in a function relationship with the input pump power as shown in fig. 5(a), the variation trend is similar to that under other transmittances, and the shortest pulse width and the highest repetition frequency are respectively 280ns and 253.8 kHz; the corresponding maximum peak power and maximum pulse energy are 373mW and 104nJ, respectively, and it can be seen from fig. 5(b) that the peak power and the pulse energy increase linearly with the input pump power. Fig. 5(c) shows the pulse sequence versus monopulse curve at different repetition frequencies.
The above is a complete implementation process of the present embodiment.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.

Claims (8)

1. The single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser comprises a semiconductor laser diode pumping source, a light focusing coupling system, a laser gain medium, a laser resonant cavity and a Q modulation device;
the semiconductor laser diode pump source, the light focusing coupling system and the laser resonant cavity are sequentially arranged; the laser resonant cavity comprises an input mirror and a coupling output mirror, the input mirror and the coupling output mirror are respectively arranged at two ends of a laser gain medium, a Q modulation device is inserted into the laser resonant cavity and is tightly attached to the back of the laser gain medium, and the laser gain medium and the Q modulation device are sequentially arranged in the laser resonant cavity according to the direction of a light path; the light focusing coupling system comprises a planoconcave cylindrical mirror, a planoconvex cylindrical mirror and a planoconvex focusing lens which are sequentially arranged;
the laser gain medium is Pr3+YLF crystals;
the Q modulation device is a single-walled carbon nanotube saturable absorber, the chiral controlled growth of the single-walled carbon nanotube saturable absorber is realized by a chemical vapor deposition method, the chirality is (7, 5), the corresponding absorption peak is at 640nm, and the corresponding carbon tube diameter distribution range is 0.79-0.92 nm;
the semiconductor laser diode pump source is a GaN blue diode pump source with polarization characteristics.
2. The red light pulse solid laser of claim 1, wherein the single-walled carbon nanotube saturable absorber is prepared by spin coating a solution of single-walled carbon nanotubes grown by manual control on a YAG or quartz substrate, the clear surface of the YAG or quartz substrate is square, and the side length range is 1-5 mm.
3. The red light pulse solid laser with single-chiral single-walled carbon nanotube saturated absorption according to claim 1, wherein the GaN blue light diode pump source has an output power of 0-3.5W, an output wavelength of 440-446nm and a central wavelength of 442 nm.
4. The red light pulse solid laser of claim 1, wherein the focal length of the light focusing coupling system is 25-75mm, and the pump light is shaped and focused on the laser gain medium.
5. The red-light pulsed solid-state laser of claim 1, wherein Pr is saturated with single-walled carbon nanotubes3+YLF crystal with 0.5 at% of trivalent Pr doping concentration, and through-plane size of 5 x 5mm2，4*4mm2，3*3mm2Or 2 x 2mm2The length of the light passing direction is 2-10 mm.
6. The red light pulse solid laser of claim 1, wherein the laser resonator is a straight resonator, the cavity length distribution is 2-100mm, the input mirror in the laser resonator is a plane mirror, the input surface is coated with AR @ 430-; the coupling output mirror in the laser resonant cavity is a plane mirror or a plano-concave mirror, the laser cavity surface of the coupling output mirror is plated with PR @ 550-.
7. The red light pulse solid laser with single-chiral single-walled carbon nanotube saturated absorption according to claim 6, wherein the input mirror and the coupling-out mirror are further simplified to Pr3+Coating optical films with the same transmittance on two end faces of a YLF crystal respectively, before coating the crystal, coating the prepared single-walled carbon nanotube solution on the output surface of the crystal in a spinning mode, and then coating a corresponding optical film to further compress the length of a laser resonant cavity to be the same as that of a laser gain medium.
8. The operating method of the single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser is characterized in that the single-chiral single-walled carbon nanotube saturated absorption red light pulse solid laser as claimed in any one of the claims 1 to 7 is adopted, and the steps are as follows:
blue pump light emitted by a GaN blue light diode pump source is focused to a laser gain medium Pr through a light focusing coupling system3 +On a YLF crystal, coupling output mirrors with different transmittances are utilized to respectively build up a laser resonance straight cavity, and the output characteristics of continuous laser are researched under different transmittances;
based on the continuous laser resonant cavity, inserting a single-chiral (7, 5) single-walled carbon nanotube saturable absorber into the laser resonant cavity, tightly attaching the saturable absorber to a laser gain medium, and adjusting the position and the angle of the saturable absorber; due to the saturated absorption characteristic of the single-chiral (7, 5) single-walled carbon nanotube saturable absorber, the Q value of the quality factor of the laser resonant cavity is adjusted to be low, and laser cannot oscillate; under this kind of state, the pumping light that continues to increase, the internal reversal particle number of laser resonator constantly accumulates, after accumulating to a certain extent, the absorption of single chirality (7, 5) single-walled carbon nanotube saturable absorber to ruddiness laser reduces suddenly, and the Q value is increaseed rapidly, and the intracavity particle number density is obviously higher than threshold value reversal particle number density, forms laser oscillation to the reversal particle number is consumed completely rapidly in the short time, realizes ruddiness pulse laser's stable output.
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CN109678138A (en) * 2019-01-09 2019-04-26 温州大学 A kind of preparation method of unidextrality single-walled carbon nanotube
CN209217428U (en) * 2018-10-26 2019-08-06 南京信息工程大学 Based on molybdenum disulfide/graphene saturable absorber Q-switch solid laser

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CN205195035U (en) * 2015-12-17 2016-04-27 山东省计量科学研究院 Laser instrument based on bitonic Q of lightning and carbon nanotube technique
CN209217428U (en) * 2018-10-26 2019-08-06 南京信息工程大学 Based on molybdenum disulfide/graphene saturable absorber Q-switch solid laser
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