Diode-pumped passively Q-switched Nd:GdVO4 laser at 1342 nm with V:YAG saturable absorber

We have demonstrated an efficient diode-pumped passively Q-switched Nd:GdVO₄ laser working at 1342 nm by using an uncoated V³⁺:YAG crystal as the saturable absorber, in which both a-cut and c-cut Nd:GdVO₄ crystals are employed. At the maximum absorbed pump power of 9.45 W, the maximum average output power can reach 519 mW and 441 mW corresponding to the output coupler with different transmission of 3% and 10% by using an a-cut Nd:GdVO₄ crystal at 1342 nm, while the shortest pulse duration could be as low as 21.7 ns and 22.3 ns with the repetition rate of 48.41 kHz and 53.25 kHz by using a c-cut Nd:GdVO₄ crystal, corresponding to the output coupler with different transmission of 3% and 10% at 1342 nm, and the single Q-switched pulse energy are 6.67 uJ and 7.06 uJ, the pulse peak power are 307 W and 316 W, respectively. The experimental results show that c-cut Nd:GdVO₄ laser can generate shorter pulse with higher peak power in comparison with a-cut one.     

Passive Q-switching performance with Co:LMA crystal in a diode-pumped Nd:LuVO<Subscript>4</Subscript> laser

A diode-pumped passively Q-switched Nd:LuVO₄ 1.34 μm laser using Co:LMA saturable absorber was successfully demonstrated. The average output power, pulse width, repetition rate of a-cut and c-cut Nd:LuVO₄ lasers were studied with different output couplers. The maximum average output power of 164 mW was obtained at the pump power of 10.3 W and the narrowest pulse width of 168 ns was achieved at repetition rate of 457 kHz under pump power of 8.59 W in a-cut Nd:LuVO₄ laser with T = 8%.     

LD泵浦高功率高斜效率Nd:YVO4声光调Q激光器

报道了采用激光二极管(LD)端面泵浦Nd:YVO4双端键合晶体高平均功率高斜效率1 064 nm声光调Q激光器。通过对大功率泵浦情况下激光晶体热透镜效应进行分析和估算,优化了模式匹配及热稳腔结构参数,实现了稳定的高功率高斜效率准连续脉冲激光输出。在泵浦功率46.8 W、最高重复频率50 kHz下,获得最大平均输出功率17.6 W,光-光转换效率为37.6%,斜效率达70.1%,脉冲宽度51.3 ns;在最低重复频率10 kHz下,获得最大单脉冲能量0.91 mJ,峰值功率为46.2 kW,脉冲宽度为19.8 ns。     

6.17-W continuous wave operation of a 2132-nm c-cut Tm,Ho:YAP pumped by a laser diode of 794.3 nm

Continuous wave (CW) operation of a c-cut Tm (5 at %), Ho (0.3 at %):YAP laser at 2132 nm wavelength were reported in this paper. In the temperature of 77 K, the Tm,Ho:YAP crystal was double end-pumped by a 21.4 W fiber-coupled laser diode (LD) at the center wavelength of 794.3 nm. Different resonator lengths and output couplers for the total pump power were tried. The resonator length was 205 mm, and the maximum CW output power of 6.17 W was acquired, corresponding to an optical-optical conversion efficiency of 28.8% and a slope efficiency of 35.6%.     

Passive mode-locking in diode-pumped c-cut Nd:LuVO<Subscript>4</Subscript> laser with a semiconductor saturable-absorber mirror

We demonstrated a diode-pumped passively mode-locked c-cut Nd:LuVO₄ picosecond laser with a semiconductor saturable-absorber mirror (SESAM) at a wavelength of 1067.8 nm. Due to the wide bandwidth of 0.48 nm, stable mode-locking has been generated with a duration as short as 3.7 ps, which is shorter than for the a-cut Nd:LuVO₄ laser. A maximum output power of 1.67 W was achieved to give a highest peak power of 3.47 KW at 18 W absorbed pump power.     

LD end-pumped c-Cut Nd:YVO<Subscript>4</Subscript>/KTP self-Raman laser at 560 nm

Intra-cavity sum frequency generation (SFG) of c-cut Nd:YVO₄ self-Raman laser was investigated for the first time. A 4 × 4 × 10 mm³ KTP crystal with a type-II phase-matching cutting angle (θ = 83.4°, φ = 0°) was used for SFG between the fundamental light at 1066 nm and first-Stokes light at 1178 nm. The laser system with different curvature radii of output couplers and different pulse repetition frequencies were investigated. At a pump power of 14 W and pulse repetition frequency of 20 kHz, the average output power of yellow-green laser at 560 nm up to 840 mW was achieved, corresponding to a slope efficiency of 7.6% and a conversion efficiency of 6% with respect to diode pump power.     

6.2 W diode-end-pumped 1313 nm Nd:YLF laser

We presented a compact and efficient diode-end-pumped 1313 nm Nd:YLF laser with an effective pump system and no additional insertion loss. The different thermal lensing effects along the ?? and ?? polarizations in an a-cut Nd:YLF crystal were investigated. 6.2 W output power of the polarized 1313 nm laser was obtained at the absorbed pump power of 17.5 W, corresponding to the optical-optical efficiency of 35% and the slope efficiency of 41%.     

Efficient parametric conversion from 1.06 to 3.8 μm by an aperiodically poled cascaded lithium niobate

We experimentally demonstrated an efficient optical parametric oscillator (OPO) with high parametric conversion from 1.0645 to 3.8?μm. An aperiodically poled magnesium oxide doped lithium niobate wafer was designed and fabricated as the nonlinear crystal of the OPO. A linearly polarized acousto-optic Q-switched Nd:YVO4 laser was used as the pump source. High pump-to-idler conversion efficiency of 18.5% was achieved with a slope efficiency of up to 21.5%. When compared with a periodically poled channel fabricated on the same wafer, under the condition of output coupler optimized for the periodically poled lithium niobate based OPO, an improvement of slope efficiency by 28.3% from 15.2% to 19.5% and total efficiency by 12.5% from 13.6% to 15.3% under the highest pump power of 11?W was realized for the pump-to-idler conversion.     

Efficient intracavity second-harmonic generation at 1063 nm in a GdCOB crystal

We report an efficient intracavity second-harmonic generation (SHG) at 1063 nm in a non-linear optical crystal, GdCa₄O(BO₃)₃ (GdCOB), performed with a diode end pumped continuous-wave (CW) Nd:GdVO₄ laser. In the case of a laser with an a-cut 0.4 at % Nd:GdVO₄ crystal frequency-doubled with a GdCOB crystal cut for Type I frequency doubling. A CW SHG output power of 2.25 W has been obtained using a 15 mm long GCOB crystal. The optical conversion efficiency with respect to the incident pump power was 12.4%.     

Continuous wave and passively Q-switched laser performance of a composite crystal bonded with three Nd:YVO<Subscript>4</Subscript> single crystals

The laser performance of a composite crystal bonded with three Nd:YVO₄ single crystals has been investigated for the first time as far as we know. The largest continuous wave output power of 2.68 W is obtained at the incident pump power of 6.2 W, giving an optical conversion efficiency of 43.1% and a slope efficiency of 45.9%. For passively Q-switched operation with Cr⁴⁺:YAG of 71% initial transmission, the shortest pulse width of 18.2 ns, the largest single-pulse energy of 19.9 μJ, and the highest peak power of 1.12 kW are achieved, with the pulse repetition rate being 44.9 kHz, at the incident pump power of 6.2 W. The composite crystal can generate more excellent laser performance, when compared with the single crystals.     

An efficient continuous-wave YVO_4/Nd:YVO_4/YVO_4 self-Raman laser pumped by a wavelength-locked 878.9 nm laser diode

We report an efficient continuous-wave self-Raman laser at 1176 nm based on a 20-mm-long composite YVO_4/Nd:YVO_4/YVO_4 crystal and pumped by a wavelength-locked 878.9 nm diode laser.A maximum output power of 5.3 W is achieved at a pump power of 26 W,corresponding to an optical conversion efficiency of 20%and a slope efficiency of 21%.The Raman threshold for the diode pump power was only 0.92 W.The results reveal that in-band pumping by a wavelength-locked diode laser significantly enhances output power and efficiency of self-Raman lasers by virtue of improved pump absorption and relieved thermal loading.     

A compact efficient continuous-wave self-frequency Raman laser with a composite YVO4/Nd:YVO4/YVO4 crystal

We report a low-threshold continuous-wave self-Raman laser with a composite YVO₄/Nd:YVO₄/YVO₄ crystal. The use of the composite crystal can reduce the thermal effects and achieve the low-threshold and high Raman output operation. The Raman threshold is as low as 2.2 W for the 808-nm diode pump. Under the pump of a diode power of 25.5 W, the highest Raman output of 2.8 W is obtained at 1175 nm, corresponding to a slope efficiency of 12% and a diode-to-Stokes optical conversion efficiency of 11%. The power fluctuation is less than 1.1% under the highest Raman output.     

Diode-pumped Nd:YxGd1-xVO4 crystal continuous-wave laser

The diode-pumped Nd:YxGd1-xVO4 crystal continuous wave (CW) laser operating at 1.06 μm with a simple plane-concave cavity and a "V-shaped" folded cavity for intracavity frequency-doubling have been studied. With the incident pump power of 8 W, an output power (1.06 μm) of 3.4 W was achieved,giving an optical conversion efficiency of 42.5%. 884 mW of stable green radiation was generated with the incident pump power of 5.9 W, giving an optical conversion efficiency of 15%.     

Diode-pumped continuous wave and Q-switched operation of Nd:LuAG crystal

The continuous wave (CW) and passively Q-switched performances of Nd:LuAG crystal were demonstrated. With a laser diode as pump source, the CW output power of 2.18 W was obtained under the pump power of 4.62 W, corresponding to the optical conversion efficiency of 47.2% and the slope efficiency of 52.2%. For Q-switching experiments, the shortest pulse width, largest pulse energy, and highest peak power were measured to be 12 ns, 50.6 μJ, and 4.21 kW, respectively.     

Improvement of passive Q-switching performance reached with a new Nd-doped mixed vanadate crystal Nd:Gd0.64Y0.36VO4

Passive Q-switching performance was found to be greatly improved by use of a new Nd-doped mixed vanadate crystal Nd:Gd0.64Y0.36VO4 compared with that achieved with Nd:YVO4 and Nd:GdVO4. At an absorbed pump power of 12 W, an average output power of 2.78 W was obtained at a pulse repetition frequency of 15.4 kHz with an optical conversion efficiency of 23.2%, and the slope efficiency was determined to be 45.5%. The resulting pulse energy, peak power, and pulse width were 181 microJ, 26.6 kW, and 6.8 ns, respectively.     

紧凑的新型Yb:GdYAB自倍频激光器

报道了一种新型自倍频晶体Yb∶Gd0.2Y0.75(BO3)4(Yb∶GdYAB)在二极管激光器端面抽运条件下的连续光激光运转。为了实现紧凑的新型全固态激光器的激光运转,设计了一个平平谐振腔,两个镜子的分开距离仅为1 cm,在这种腔结构下,得到了中心波长为1044 nm的基频激光输出,当吸收抽运功率为4.22 W时,基频激光的最大输出功率为1.38 W,相应功率曲线最大斜效率为54%。为获得有效的自倍频激光输出,换用了平凹腔进行了自倍频实验。自倍频光运转阈值仅为900 mW,在吸收抽运功率为3.9 W的条件下,得到144 mW的自倍频绿色激光输出,获得从二极管激光器到绿光的直接光-光转换效率为3.7%。实验结果表明Yb∶GdYAB作为一种新型的自倍频晶体,对于紧凑的1μm波段的基频光和自倍频可见光激光器都有着很大的应用潜力。     

Lasing of diode-pumped c-cut Tm, Ho:YAlO3

We report on a diode-pumped Tm, Ho:YAlO₃ (c-cut) laser operating at 274 K. The maximum output power reaches 163 mW at an absorbed pump power of 2.3 W. A conversion efficiency from the absorbed pump power to laser output of 7.1% is demonstrated in Tm, Ho:YAlO₃, corresponding to a slope efficiency of 11.1%. The output center wavelength of Tm, Ho:YAlO₃ is 2102 nm with about a 2-nm FWHM. As far as we know, our work represents the first investigation of the laser performance of c-cut Tm, Ho:YAlO₃ at 274 K.     

Thermal Lensing, Laser Performance at 1.06 μm and 0.53 μm of a NYAB Laser End-pumped by a Diode-laser-array

The thermal lensing, output characteristics of an end-pumped NYAB laser with high pump power levels and operated at the fundamental wavelength, and the manner of self-frequency-doubling, have been investigated. The thermal lensing in the NYAB crystal was found to be significantly stronger than that in Nd:YVO4 crystal. A maximum output of 3.2 W at 1.06 μm was achieved with an optical conversion efficiency of 29.1％ and an average slope efficiency of 37.5％. These results were found to be slightly inferior to those of Nd:YVO4 crystal. When operated in the fashion of selffrequency-doubling, 23 mW green output was obtained at the incident pump power of 5 W, such inefficient operation was attributed to the large mode size in the NYAB crystal.     

Efficient Tm:LuVO₄ laser at 1.9 μm

We report an efficient laser-diode-pumped Tm-doped LuVO? crystal laser at about 1.9 μm. For the first time to our knowledge, the π-polarized Tm:LuVO? laser was achieved. The maximum output power and slope efficiency were 1.32 W and 28.7%, respectively. By comparison, it has been found that the a-cut Tm:LuVO? crystal should be more suitable for applications in high-power lasers. The central laser wavelength was observed to be located at about 1.9 μm and shifted to shorter with the increase of intracavity light intensity, which could be explained based on the reabsorption of light in the Tm:LuVO? crystal.     

Thermal Lensing, Laser Performance at 1.06 μm and 0.53 μm of a NYAB Laser End pumped by a Diode laser array

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｓｅｌｆ ｆｒｅｑｕｅｎｃｙ ｄｏｕｂｌｉｎｇｌａｓｅｒｃｒｙｓｔａｌｓ,ｗｈｉｃｈｃｏｍｂｉｎｅｔｗｏｄｉｆｆｅｒｅｎｔｆｕｎｃｔｉｏｎｓｏｆｌａｓｅｒｅｍｉｓｓｉｏｎａｎｄｆｒｅｑｕｅｎｃｙｃｏｎｖｅｒｓｉｏｎ ,ｐｒｏｖｉｄｅａｓｉｍｐｌｅｗａｙｏｆｇｅｎｅｒａｔｉｎｇｃｏｈｅｒｅｎｔｖｉｓｉｂｌｅｒａｄｉａｔｉｏｎ .Ａｍｏｎｇｔｈｅｖａｒｉｏｕｓｓｅｌｆ ｆｒｅｑｕｅｎｃｙ ｄｏｕｂｌｉｎｇｃｒｙｓｔａｌｓ ,ｎｅｏｄｙｍｉｕｍｙｔｔｒｉｕｍａｌｕｍｉｎｕｍｂｏｒａ…