High-power ultraviolet 278 nm laser from fourth-harmonic generation of a Nd:YAG laser in CsB3O5

We demonstrate a high-power UV 278 nm laser by fourth-harmonic generation (FHG) of a 1112 nm Nd:YAG laser in a nonlinear optical (NLO) crystal CsB3O5 (CBO) for the first time, to our best knowledge. A 30 W level diode-pumped Q-switched Nd:YAG laser at 1112 nm with beam quality factor M2=1.2 was used as the fundamental light source at a pulse width of 500 ns. With an LiB3O5 crystal, the 1112 nm laser was first frequency-doubled to 556 nm with an average output power of 13.5 W. It was then frequency doubled again in a CBO crystal to obtain the FHG output at 278 nm. The maximum average output power of the 278 nm laser is up to 1.5 W. The results demonstrated that CBO crystal is a promising NLO material for UV high-power lasers below 300 nm.     

La2CaB10O19晶体高效紫外激光输出研究

La2CaB10O19(LCB)为可通过Nd∶YAG激光三倍频产生355 nm紫外激光的非线性光学晶体,其光学性能可与商用化的LiB 3O 5(LBO)晶体媲美,但抗潮解特性优势明显。本文对用LCB晶体实现355 nm紫外激光输出的三倍频产生过程进行了优化设计,利用走离补偿方法来提高激光输出转换效率。通过在光路中加入沿θ=45°方向切割、厚度为1.2 mm的方解石晶体走离补偿片,在脉冲宽度为60 ns、重复频率10 kHz的激光参数下实现355 nm输出功率由12 W提升至20 W;在脉冲宽度为25 ps、重复频率为10 Hz的激光参数下355 nm转换效率由28.3%提升至35.2%。     

Diode-laser-based ultraviolet-absorption sensor for high-speed detection of the hydroxyl radical

A new diode-laser-based UV-absorption sensor for high-speed detection of the hydroxyl radical (OH) is described. The sensor is based on sum-frequency generation of UV radiation at 313.5 nm by mixing the output of a 763-nm distributed-feedback diode laser with that of a 532-nm high-power, diode-pumped, frequency-doubled Nd:YVO4 laser in a beta-barium borate crystal. Approximately 25 microW of UV radiation is generated and used to probe rotational transitions in the A2 Sigma+ -X2II (v' = 0, v" = 0) electronic transition of OH. Single-sweep, single-pass measurements of temperature and OH concentration in a stoichiometric C2H4-air flame are demonstrated at rates up to 20 kHz.     

周期极化KTiOPO4晶体和频单块非平面环形腔激光产生连续单频589nm黄光

单次通过周期极化KTiOPO₄晶体和频单块非平面环形腔1064 nm与1319 nm激光产生连续单频589 nm黄光. 通过琼斯矩阵模拟计算对单块非平面Nd:YAG晶体参数进行了优化设计, 实验获得1080 mW和580 mW的连续单频1064 nm和1319 nm激光输出. 两束激光单次通过周期极化KTiOPO₄晶体和频产生14.8 mW, M²=1.14的589 nm黄光, 相应的和频效率为0.9%. 研究了周期极化KTiOPO₄温度对和频效率的影响, 得到其温度接收带宽为1.5℃. 通过改变1064 nm Nd:YAG晶体的温度可实现589 nm黄光波长精确对应钠原子D_2a吸收谱线, 调谐精度达到0.164 pm.     

Violet light generation by frequency doubling of GaAlAs diode laser using a metallo-organic complex crystal ZnCd(SCN)4

Violet 404-nm radiation is generated by type-I single-pass frequency doubling of the output of an GaAlAs diode laser in critically phase-matched ZnCd(SCN)₄ (ZCTC) crystal, a metallo-organic complex crystal. In this paper, its refractive index and second-harmonic generation phase-matching angles are reported. Using a 3-mm-long ZCTC crystal, a diode laser power of 473 mW generated 390 μW of second-harmonic radiation. More recently, 380-nm, 20 μW ultraviolet (UV) radiation is also realized by frequency doubling of the 100 mW output of a continuous-wave Ti:sapphire laser at 760 nm. ZCTC is a promising UV nonlinear optical candidate material for frequency doubling of diode lasers.     

Generation of Anti-Stokes Line in Fundamental Mode of Photonic Crystal Fibre

A photonic crystal fibre （PCF） with zero-dispersion wavelength around 800 nm is designed and fabricated. Simulated results show that the zero-dispersion wavelength of fundamental mode for this PCF is at 826nm, and phase-matched four-wave mixing can be achieved in fundamental mode. Using 20ors Ti：sapphire laser with central wavelength at 810nm as pump, the anti-Stokes line around 610hm ＆ generated efficiently. The output signal has a Gaussian-like profile, which indicates that the anti-Stokes signal is in the fundamental mode of the PCF. The energy of anti-Stokes signal is higher than that of residual pump laser and the maximum ratio of the anti-Stokes signal to the pump component in the output spectrum is estimated to be 1.2.     

高峰值功率KDP晶体四倍频266nm紫外激光器

报道了一种灯泵浦结构的Nd:YAG晶体电光调Q高峰值功率266nm紫外激光器。结合磷酸二氢钾(KDP)晶体性质,基于倍频理论,分析了考虑走离效应情况下存在相位失配量时KDP晶体长度对转换效率的影响。该激光器采用紧凑的平平腔结构,灯泵浦Nd:YAG晶体电光调Q 1064nm激光作为基频光,腔外采用Ⅱ类匹配磷酸钛氧钾(KTP)和Ⅰ类匹配KDP分别作为二倍频和四倍频晶体。利用能量计、示波器等仪器进行测量,激光器重复频率1Hz时,获得脉宽6.0ns,单脉冲能量35mJ的266nm紫外激光输出,峰值功率高达5.83 MW;当重复频率10Hz时,获得单脉冲能量28.9mJ的266nm紫外激光。532~266nm转换效率最高可达31.9%。利用该高峰值功率、窄脉宽266nm紫外激光器,能够实现激光打标、激光雕刻。     

高峰值功率KDP晶体四倍频266 nm紫外激光器

报道了一种灯泵浦结构的Nd:YAG晶体电光调Q高峰值功率266 nm紫外激光器。结合磷酸二氢钾(KDP)晶体性质,基于倍频理论,分析了考虑走离效应情况下存在相位失配量时KDP晶体长度对转换效率的影响。该激光器采用紧凑的平平腔结构,灯泵浦Nd:YAG晶体电光调Q 1064 nm激光作为基频光,腔外采用Ⅱ类匹配磷酸钛氧钾(KTP)和Ⅰ类匹配KDP分别作为二倍频和四倍频晶体。利用能量计、示波器等仪器进行测量,激光器重复频率1 Hz时,获得脉宽6.0 ns,单脉冲能量35 mJ的266 nm紫外激光输出,峰值功率高达5.83 MW;当重复频率10 Hz时,获得单脉冲能量28.9 mJ的266 nm紫外激光。532~266 nm转换效率最高可达31.9%。利用该高峰值功率、窄脉宽266 nm紫外激光器,能够实现激光打标、激光雕刻。     

波长可调谐的瓦级连续橙红光激光器

介绍了基于复合腔结构的全固态波长可调谐的连续橙红色激光的输出特性。该复合腔由一个使用周期极化晶体MgO:PPLN的信号光单谐振光参量振荡器和一个LD侧面泵浦Nd:GdVO₄晶体的1 062.9 nm基频光谐振腔构成。s-偏振1 062.9 nm泵浦光抽运单谐振光参量振荡器产生s-偏振信号光腔内独立振荡。通过复合腔结构的优化设计,使独立振荡的p-偏振1 062.9 nm基频光与s-偏振信号光在2个子腔的重叠区内通过Ⅱ类角度匹配KTP晶体的腔内和频过程获得橙红色激光。当MgO:PPLN晶体的调谐温度从30 ℃上升至200 ℃时,s-偏振信号光的中心波长产生红移,导致其与p-偏振1 062.9 nm基频光和频产生的橙红色激光的中心波长从620.2 nm红移至628.9 nm。同时测得中红外波段闲频光的中心波长从3 714.2 nm蓝移至3 438.3 nm。在30 ℃最低设定温度时, 中心波长620.2 nm的橙红色激光和中心波长3 714.2 nm的闲频光最大连续输出功率分别达到2.0 W和2.9 W。     

Compact all-solid-state continuous-wave single-frequency UV source with frequency stabilization for laser cooling of Be<Superscript>+</Superscript> ions

A compact setup for generation, frequency stabilization, and precision tuning of UV laser radiation at 313 nm was developed. The source is based on frequency quintupling of a C-band telecom laser at 1565 nm, amplified in a fiber amplifier. The maximum output power of the source at 313 nm is 100 mW. An additional feature of the source is the high-power output at the fundamental and the intermediate second- and third-harmonic wavelengths. The source was tested by demonstration of laser cooling of Be⁺ ions in an ion-trap apparatus. The output of the source at the third-harmonic wavelength (522 nm) was used for stabilization of the laser frequency to molecular iodine transitions. Sub-Doppler spectroscopy and frequency measurements of hyperfine transitions in molecular iodine were carried out in the range relevant for the Be⁺ laser cooling application.     

自锁模飞秒掺铬的镁橄榄石激光器的实验研究

用波长为1.06μm的Nd:YAG激光器泵浦Cr⁴⁺:forsterite晶体,实现了Cr⁴⁺:forsterite激光器的自锁模飞秒激光运转,在吸收泵浦功率为8W的条件下,得到了脉冲宽度为85fs,中心波长为1246nm,平均输出功率为200mW的稳定锁模输出。     

Neodymium-doped phosphate fiber lasers with an all-solid microstructured inner cladding

We report on high-power fiber lasers based on index-guiding, all-solid neodymium-doped (Nd-doped) phosphate photonic crystal fiber (PCF) with a hexagonal-shaped inner cladding. The optimum fiber laser with a 36 cm length active fiber, generated up to 7.92 W output power at 1053 nm, which benefited from a high absorption coefficient for pump power due to its noncircular inner cladding. The guiding properties of the all-solid PCF were also investigated. A stable mode with a donut-shaped profile and a power-dependent laser beam quality have been observed experimentally and analyzed.     

Narrow-band UV radiation (250–260 nm) from intracavity doubling a single-mode ring dye laser

Generation of continuous-wave, tunable UV radiation (250–260 nm) by intracavity doubling a coumarin-515 ring dye laser is described. A cooled (200–280 K) ADP crystal with end faces cut at Brester's angle is placed inside the laser ring cavity which has been compensated for astigmatism and coma. UV output powers at 254 nm of 120 μW and 60 μW are achieved with the laser operating multimode (bandwidth ? 20 GHz) and single-mode (bandwidth ? 50 MHz), respectively. Continuous single-mode scans over the 253.7 nm mercury profile demonstrate sub-Doppler resolution of the Hg 6s6p ³P^O₁ - 6s²¹S₀ transition.     

基于水、风混合型冷却系统的LD端面泵浦全固态连续绿光激光器

为了简化激光器冷却系统,减小体积,降低成本,设计出一种基于水、风混合型的冷却系统,具有水冷和风冷的优点,可以实现稳定的绿光激光输出.采用结构简单、紧凑的平-凹腔设计,其端镜为平面镜,输出镜为凹面镜,曲率半径R=1 m,腔长L=165 mm,获得较稳定的单端泵浦Nd:YVO4腔内倍频KTP连续绿光激光输出.当晶体吸收的泵浦功率为24.3 W时,532 nm激光功率达到4.2 W,光-光转换效率达到17.2%.在绿光输出功率为3 W的情况下,观测到的变化范围在2.5%左右,温度变化范围在0.1°左右.实验结果表明,该冷却系统能够较好地转移晶体热效应产生的热量,实现转化效率较高的绿光输出,有利于实现高功率激光器的微型化.     

高能量高转换效率355 nm紫外激光器

为了得到一种三倍频效率高达60%的355 nm脉冲激光器,采用曲率半径分别为2 m的凹凸高斯镜和9 m的平凹全反镜组合作为谐振腔,加以电光调Q,得到1 064 nm高光束质量激光输出,再将其进行行波放大,获得重复频率10 Hz、脉宽7.3 ns、单脉冲能量1.01 J的1 064 nm基频光输出。利用Ⅰ类相位匹配LBO晶体进行二倍频、Ⅱ类相位匹配LBO晶体进行三倍频以得到波长为355 nm的紫外光输出。通过二倍频和三倍频输出特性和非线性晶体参数的分析和实验调试,最终获得了单脉冲能量为608 mJ、脉宽为5.7 ns、线宽为2 nm的紫外激光输出。通过优化二倍频的转换效率,可使1 064 nm基频光到三倍频得到的355 nm紫外光的转换效率达60%。     

二极管泵浦全固态589 nm脉冲激光器

 报道了一台二极管激光器(DL)泵浦的全固态Nd:YAG和频激光器,激光是由Nd:YAG晶体的1 064 nm 和1 319 nm 谱线外腔和频产生,以6 mm×6 mm×12 mm KTP为和频晶体,采用Ⅱ类临界相位匹配, 在400 Hz重复频率下,当分别注入3.05 W和2.46 W的1 064 nm和1 319 nm调Q脉冲到KTP晶体时,和频最大输出达到了1.3 W,脉宽为35 ns,线宽优于3 GHz,和频效率达到了23.5％, 光束质量因子分别为1.84和1.93。实验结果表明采用激光二极管阵列泵浦Nd:YAG/ KTP 腔外和频技术是获得黄激光的高效方法, 并通过精确控制谐振腔内标准具的倾角与温度,和频输出波长可精确调谐到Na D2线。     

Watt-level Pr~(3+):YLF deep red laser pumped by a fiber-coupled blue LD module or a single-emitter blue LD

A power-scaled laser operation of Pr:YLi F4(YLF)crystal at 720.9 nm pumped by a 443.6 nm laser diode(LD)module was demonstrated.The 20 W module was used to pump the Pr:YLF crystal,and a maximum output power of 3.03 W with slope efficiency of 30.04%was obtained.In addition,a 5 W blue LD was also used to pump the Pr:YLF laser,and a maximum output power of 0.72 W was obtained at room temperature.The output power was limited by the wavelength mismatch between the single-emitter LD and the absorption peak of the crystal.     

532 nm激光泵浦硝酸钡晶体产生外腔拉曼激光

 由于硝酸钡晶体具有很强的对称振动(频率1 047 cm^-1)和较高的拉曼增益,可以用来产生受激拉曼激光。采用单端泵浦的外置拉曼振荡腔与双棱镜分光装置进行了硝酸钡晶体拉曼激光实验,泵浦源为倍频Nd: YAG的532 nm激光,硝酸钡晶体通过水溶液降温法生长,尺寸为10 mm×10 mm×48 mm,采用特殊镀膜的腔镜对各阶斯托克斯光进行优化选择。在泵浦源达到65 mJ时,获得21 mJ一阶斯托克斯光,输出波长为563 nm,以及16 mJ的二阶斯托克斯光,输出波长为599 nm,受激拉曼散射SRS最大的整体转换效率（包含一阶、二阶斯托克斯光之和）为56.3%。     

Performance of a liquid-nitrogen-cooled CW Tm, Ho:YLF laser

A liquid-nitrogen-cooled Tm, Ho:YLF laser is constructed with a 10-mm-long Tm(6%) and Ho(0.5%) co-doped yttrium lithium fluoride crystal pumped by a laser diode operating at 792 nm. The laser outputpower is improved by cooling the Tm, Ho:YLF crystal from 300 to 77 K. When the crystal is kept at 77K, the laser threshold pump power is 230 mW, the slope efficiency is 27.4%, and the maximum optical-to-optical efficiency is 19.9%. At the same time, the relation between the input power and the output powerat different temperatures is obtained.     

Tunable second harmonic generation from a Kerr-lens mode-locked Yb:YCa_4O(BO_3)_3 femtosecond laser

We experimentally demonstrated a diode-pumped Kerr-lens mode-locked femtosecond(fs) laser with a self-frequency doubling Yb:YCa_4O(BO_3)_3 crystal.Sub-40 fs laser pulses were directly generated from the oscillator without extracavity compression.The central wavelength was tunable from 1039 nm to 1049 nm with a typical bandwidth of 35 nm and an average output power of 53 mW.For the first time,a self-frequency doubled second harmonic green laser with tunable range from 519 nm to 525 nm was observed.