An all-solid-state high power quasi-continuous-wave tunable dual-wavelength Ti：sapphire laser system using birefringence filter

This paper describes a tunable dual-wavelength Ti：sapphire laser system with quasi-continuous-wave and high-power outputs. In the design of the laser, it adopts a frequency-doubled Nd：YAG laser as the pumping source, and the birefringence filter as the tuning element. Tunable dual-wavelength outputs with one wavelength range from 700 nm to 756.5 nm, another from 830 nm to 900mn have been demonstrated. With a pump power of 23 W at 532 nm, a repetition rate of 7 kHz and a pulse width of 47.6 ns, an output power of 5.1 W at 744.8 nm and 860.9 nm with a pulse width of 13.2 ns and a line width of 3 nm has been obtained, it indicates an optical-to-optical conversion efficiency of 22.2%.

A 54-fs diode-pumped Kerr-lens mode-locked Yb:LuYSiO_(5) laser

We demonstrate a Kerr-lens mode-locked Yb:Lu YSiO_(5)(Yb:LYSO)laser with the pulse duration of 54 fs,corresponding to a spectral bandwidth of 25 nm centered at 1062 nm.To the best of our knowledge,this is the shortest pulse duration obtained from Yb:LYSO laser.At the repetition rate of 378.3 MHz,an output power of 111.6 m W is obtained using an output coupler with 0.6%transmittance,which can maintain long-time stable mode-locking more than 13 h.

All-solid-state far-UVC pulse laser at 222 nm wavelength for UVC disinfection

A 222 nm all-solid-state far-ultraviolet C(UVC)pulse laser system based on an optical parametric oscillator(OPO)and second-harmonic generation(SHG)usingβ-Ba2BO4(BBO)crystals was demonstrated.Pumped by a Nd∶Y3Al5O12 laser with a repetition rate of 100 Hz at 355 nm,the maximum signal laser pulse energy of 1.22 mJ at 444 nm wavelength was obtained from the BBO-OPO system,corresponding to a conversion efficiency of 27.9%.The maximum output pulse energy of 164.9μJ at the 222 nm wavelength was successfully achieved,corresponding to an SHG conversion efficiency of 16.2%.Moreover,the tunable output wavelength of UVC light from 210 nm to 252.5 nm was achieved.

High power diode-pumped passively mode-locked Nd:YVO_4 laser at repetition rate of 3.2 GHz

A compact high power diode-pumped passively mode-locked Nd:YVO_4 laser with high repetition rate is realized.Using an Nd:YVO_4 crystal and a semiconductor saturable absorber mirror(SESAM) in the oscillator, the picosecond pulse output with an average power of 1.38 W, a repetition rate of 3.24 GHz, and a pulse duration of 11.4 ps is achieved. After one stage of amplification, the final output power reaches 11.34 W, corresponding to a total optical-to-optical efficiency of about 32%. The root mean square(RMS) value of power fluctuation is demonstrated to be less than 0.6% in 24 hours,showing a superior stability with the compact configuration.

Short Pulse Width and High Peak Power 457 nm Deep Blue Laser with V-Type Cavity

An intracavity frequency doubling acousto-optically Q-switched Neodymium-doped Yttrium Orthvanadate (Nd:YVO4) 457 nm blue laser by employing a three-mirror folded cavity was demonstrated. With the incident pump power of 40.4 W, the maximum average output power of 439 mW 457 nm laser, and the minimum pulse duration of 86.14 ns and the maximum peak power of 510 W were achieved at 10 kHz. The M2 factors are 1.23 and 1.61 in X and Y directions, respectively. The power stability in two hours is better than 2%.

High-power passively Q-switched 2 μm all-solid-state laser based on a Bi_2Te_3 saturable absorber

By using the ultrasound-assisted liquid phase exfoliation method, Bi_2Te_3 nanosheets are synthesized and deposited onto a quartz plate to form a kind of saturable absorber(SA), in which nonlinear absorption properties around 2 μm are analyzed with a home-made mode-locked laser. With the as-prepared Bi_2Te_3 SA employed,a stable passively Q-switched all-solid-state 2 μm laser is successfully realized. Q-switched pulses with a maximum average output power of 2.03 W are generated under an output coupling of 5%, corresponding to the maximum single-pulse energy of 18.4 μJ and peak power of 23 W. The delivered shortest pulse duration and maximum repetition rate are 620 ns and 118 k Hz under an output coupling of 2%, respectively. It is the first presentation of such Bi_2Te_3 SA employed in a solid-state Q-switched crystalline laser at 2 μm, to the best of our knowledge. In comparison with other 2 D materials suitable for pulsed 2 μm lasers, the saturable absorption performance of Bi_2Te_3 SA is proved to be promising in generating high power and high-repetition-rate 2 μm laser pulses.

Graphdiyne as a saturable absorber for 2-µm all-solid-state Q-switched laser

As a novel one-atom-thick carbon allotrope,graphdiyne(GDY)has attracted wide interest in two-dimensional materials owing to its unique feature with a planar layer comprising sp2-and sp-hybridized carbon atoms and a direct natural bandgap.A high-quality saturable absorber(SA)based on GDY was successfully fabricated,and the nonlinear saturable absorption properties were investigated.A compact diode-pumped solid-state passively Q-switched laser based on the as-prepared GDY-SA could be operated at 2µm.The Q-switched laser delivered a maximum average output power of 1.29 W at a central wavelength of 1908.41 nm with up to 54.8%slope efficiency.A repetition rate of 91.58 kHz and single pulse energy of 23.08µJ were obtained.This work is the first application of GDY as an SA to generate all-solid-state pulsed lasers.These results indicate that GDY is a promising SA for solid-state pulsed lasers and has further application potential for ultrafast photonic devices in the 2-µm region.

All-solid-state pseudocapacitive micro-supercapacitors from laser-treated polymer derivatives

We report a simple method for fabricating all-solid-state micro-supercapacitors, utilizing laser writing technology. Porous graphene films with three-dimensional networks induced by laser from commercial polymer was acted as scaffold for loading MnO2, a typical pseudocapacitive materials. Using gel electrolyte, all-solid-state pseudocapacitive micro-supercapacitors were fabricated. Compare to traditional printing and lithography techniques produced micro-supercapacitors, the as-fabricated devices demonstrate high volumetric capacitances, good stability and low leakage current, indicating a scalable and facile approach for future energy storage devices in portable microelectronics.

Comprehensive multiphysics analysis of high-energy nanosecond lasers based on liquid-cooled Nd-doped rods pumped by flashlamps

Ultra-short pulse,ultra-intense(USUI)lasers have become indispensable tools for scientific research.High-energy pump lasers are crucial for ensuring adequate energy and beam quality of these USUI lasers.Pump lasers with rod amplifiers are a cost-effective and reliable option for meeting high-energy pump requirements.However,there is a notable dearth of comprehensive reports on the design of high-energy rod amplifiers.This study provides a detailed analysis of rod amplifiers,focusing primarily on the pump unit utilized at SULF-10 PW and SEL-100 PW prototypes.The analysis covers aspects such as gain management,thermal effects,and spatiotemporal evolution.

氟硼铍酸钾晶体及深紫外全固态激光

深紫外(DUV)全固态相干光源(λ<200 nm)在前沿科学、高技术等领域有着重要应用。将商业化的高功率可见/近红外全固态激光通过非线性光学晶体进行多级变频是实现该光源的有效途径。从双折射和色散两个方面阐述了满足深紫外非线性光学晶体的基本条件,介绍了深紫外非线性光学晶体的探索和实用化所需克服的技术困难;重点以氟硼铍酸钾(KBBF)和氟硼铍酸铷(RBBF)晶体为代表,介绍其发现过程、晶体生长技术、棱镜耦合器件技术、光学性质以及深紫外波段倍频能力;还详细介绍了相关的深紫外全固态激光的研究进展,以及该光源在先进科学仪器上的应用,尤其是在超高分辨率光电子能谱仪方面的应用和取得的重要成果。最后展望了深紫外非线性光学晶体及深紫外全固态激光技术的发展方向。

Picosecond Stimulated Raman Scattering of SrWO4 Crystal

Stimulated Raman scattering （SRS） of picosecond pulses is investigated in a new crystal SrWO4. The second harmonic generation of a mode-locked Nd：YAG laser system is used as the pump source. In an external singlepass configuration, the SRS thresholds for the first to the fourth Stokes lines are measured. For the first Stokes line, the steady-state gain coefficient of the SrWO4 crystal is calculated to be 15.96cm//GW. In our experiment, as many as five Stokes lines （559.23 nm, 589.61 nm, 623.49 nm, 661.50 nm, 704.44 nm） and three anti-Stokes lines （506.97nm, 484.34 nm, 463.65nm） are observed, and the total conversion efficiency is as high as 62%.

全固态连续228 nm深紫外激光器研究

采用V型腔腔内二倍频和透镜聚焦方式腔外四倍频结构,基于Nd:YVO_(4)准三能级激光系统914 nm基频光级联非线性光学频率变换获得连续波228 nm激光输出。在通常情况下,与脉冲运转方式相比,连续运转激光实现透镜聚焦腔外倍频需要较高的平均功率和较好的光束质量。为了获得较高457 nm连续激光输出性能,理论计算V型腔分臂的长度变化对腔内不同位置光斑大小的影响;实验研究了V型腔不同分臂长度对LD端泵Nd:YVO_(4)/LBO产生457 nm激光输出性能的影响。最终,在泵浦功率为26 W时,获得功率为2.2 W的TEM_(00)模连续波457 nm激光输出,利用I类临界相位匹配BBO晶体对其进行腔外倍频,获得功率为6 mW的228 nm连续波深紫外激光,激光光斑呈椭圆形,一小时内功率稳定性为1.8%。

Experiments on Nanosecond Optical Parametric Generation for 486.0 nm in BBO Crystal

In this paper, an injection-seeded nanosecond optical parametric generation (OPG) using BBO crystal, which combines relatively low thresholds with a simple and compact configuration, was demonstrated. By seeding externally with distributed feedback (DFB) diode laser at 1313 nm wavelength, pumped by 355 nm laser pulse, the maximum blue laser output power of 1.36 W at a rate of 100 Hz and with linewidth less than 0.13 nm were obtained, and the maximum optical to optical conversion efficiency was to 21.2%.

基于国产商用CLBO晶体的高转换效率、高功率深紫外266 nm激光

深紫外激光具有光子能量高、波长短等特点,在激光加工、半导体光刻等领域中具有重要的应用价值。固体激光非线性频率变换是实现高功率、高相干性深紫外激光输出的主要方式之一。采用全固态532 nm激光作为基频光、国产商用CsLiB_(6)O_(10)(CLBO)晶体作为频率变换晶体,在基频光功率为34.2 W时,实现了平均功率为14 W、重复频率为100 kHz、脉冲宽度为1.8 ns的266 nm深紫外激光输出,光-光转换效率达到41%。该深紫外光源具有效率高、结构紧凑的优点,验证了国产商用CLBO晶体的实用性,可进一步获得更稳定、更高功率的深紫外激光输出。

High-efficiency 50 W burst-mode hundred picosecond green laser

We report high-energy,high-efficiency second harmonic generation in a near-infrared all-solid-state burst-mode picosecond laser at a repetition rate of 1 kHz with four pulses per burst using a type-I noncritical phase-matching lithium triborate crystal.The pulses in each burst have the same time delay(~1 ns),the same pulse duration(~100 ps)and different relative amplitudes that can be adjusted separately.A mode-locked beam from a semiconductor saturable absorber mirror is pulse-stretched,split into seed pulses and injected into a Nd:YAG regenerative amplifier.After the beam is reshaped by aspheric lenses,a two-stage master oscillator power amplifier and 4f imaging systems are applied to obtain a high power of^100 W.The 532 nm green laser has a maximum conversion efficiency of 68%,an average power of up to 50 W and a beam quality factor M^2 of 3.5.

High-energy,high-repetition-rate ultraviolet pulses from an efficiency-enhanced,frequency-tripled laser

In this study,a high-energy,temporally shaped picosecond ultraviolet(UV)laser running at 100 Hz is demonstrated,with its pulses boosted to 120 mJ by cascaded regenerative and double-pass amplifiers,resulting in a gain of more than 10^(8).With precise manipulation and optimization,the amplified laser pulses were flat-top in the temporal and spatial domains to maintain high filling factors,which significantly improved the conversion efficiency of the subsequent third harmonic generation(THG).Finally,91 mJ,470 ps pulses were obtained at 355 nm,corresponding to a conversion efficiency as high as 76%,which,as far as we are aware of,is the highest THG efficiency for a high-repetition-rate picosecond laser.In addition,the energy stability of the UV laser is better than 1.07%(root mean square),which makes this laser an attractive source for a variety of fields including laser conditioning and micro-fabrication.

Long-pulse, single-frequency 1064 nm laser and frequency doubling

An all-solid-state single-frequency 1064 nm laser with a 100 μs pulse width, 500 Hz repetition rate and 700 m J single pulse energy is designed using seed injection and a three-stage master oscillator power amplifier(MOPA) construction.Using this as a basis, research on long-pulse laser frequency doubling is carried out. By designing and optimizing the lithium triborate(LBO) crystal, the theoretically calculated maximum conversion efficiency ηmax reaches 68% at M2=1, while ηminis 33% at M2=3. Generation of 212 m J pulses of green light with a repetition rate as high as500 Hz is obtained from a fundamental energy of 700 m J. The experimental conversion efficiency reaches 31% and the power stability is better than±1%.

Broadband nonlinear optical response of graphdiyne for mid-infrared solid-state lasers

Graphdiyne(GDY),a novel all-carbon nanomaterial,is considered the most easily synthesized and stable carbon allotrope,positioning it as a promising photoelectric material.Herein,we successfully fabricated a high-quality GDY saturable absorber and saturable absorber mirror.Both broadband nonlinear saturable absorption and ultrafast relaxation dynamic properties in midinfrared region of the GDY were investigated.All solid-state diode-pumped short and ultrashort pulsed lasers were realized using the GDY absorber at wavelengths of 2 and 2.8μm,respectively.The results were then theoretically analyzed.This is the first presentation of ultrashort pulsed lasers in the mid-infrared region with GDY absorbers.These results resolutely confirm that GDY could be an optional broadband SA for all solid-state mid-infrared pulsed lasers,and they evidence its promising applications in mode-locked ultrafast lasers.

High-energy,hundred-picosecond pulsed 266 nm mid-ultraviolet generation by a barium borate crystal

We present a high-energy,hundred-picosecond(ps)pulsed mid-ultraviolet solid-state laser at 266 nm by a direct second harmonic generation(SHG)in a barium borate(BaB_(2)O_(4),BBO)nonlinear crystal.The green pump source is a 710 mJ,330 ps pulsed laser at a wavelength of 532 nm with a repetition rate of 1 Hz.Under a green pump energy of 710 mJ,a maximum output energy of 253.3 mJ at 266 nm is achieved with 250 ps pulse duration resulting in a peak power of more than 1 GW,corresponding to an SHG conversion efficiency of 35.7%from 532 to 266 nm.The experimental data were well consistent with the theoretical prediction.To the best of our knowledge,this laser exhibits both the highest output energy and highest peak power ever achieved in a hundred-ps/ps regime at 266 nm for BBO-SHG.

LD端面抽运全固态声光调Q228.5nm深紫外激光器

采用三镜折叠V型谐振腔、声光调Q技术和三硼酸锂(LBO)晶体,对二极管端面抽运Nd∶YVO_(4)的914 nm基频光进行腔内倍频,实现了457 nm激光输出,利用I类相位匹配偏硼酸钡(BBO)晶体对457 nm蓝光进行腔外倍频,获得了228.5 nm深紫外激光。当抽运功率为17 W时,获得了平均功率为10 mW的228.5 nm深紫外激光输出,脉冲宽度为64.26 ns,重复频率为10 kHz。2 h内的激光输出稳定度为±2%。