Dual-wavelength bandwidth-narrowed output of a high-power diode laser using a simple external cavity

Using an external cavity consisting of an etalon and a mirror, dual-wavelength operation of a high-power broad-area multi-stripe diode laser is achieved. The reflection of the etalon is used as the output beam of the system. The free-running bandwidth of the laser diode is about 2.0 nm. At dual-wavelength operation, the bandwidth of each wavelength component is narrowed to about 0.07 nm, while the space between them is 1.65 nm, determined by the FSR of the etalon. We obtain an available dual-wavelength output power of 2.0 W at the drive current of 6.5 A. The power ratio of the components at two different wavelengths can be changed by changing the temperature of the diode laser. To tune the wavelength of the dual-wavelength output, the temperature of the laser diode and the tilt angle of the etalon are changed simultaneously PACS 42.55.Px; 42.60.Fc; 42.60.Da     

Diode-pumped continuous-wave Nd:YVO<Subscript>4</Subscript> laser with self-frequency Raman conversion

Continuous-wave operation of a diode-pumped Nd:YVO₄ laser with self-frequency Raman conversion is demonstrated. The threshold of Raman generation was measured to be 1.3 W of laser diode power. The maximum output power of Stokes radiation at the wavelength of 1177 nm was up to 50 mW at a laser diode pump power of 2.3 W, corresponding to the slope efficiency of 5%. The beam quality M² of the Stokes radiation was about 1.4. The fluctuations of the Stokes power were minimised down to 4%. PACS 42.55.Ye; 42.60.Pk; 42.65.Dr     

High-repetition-rate eye-safe intracavity KTA OPO driven by a diode-end-pumped Q-switched Nd:YVO4 laser

An eye-safe, high-repetition-rate, single-resonant nanosecond intracavity optical parametric oscillator (IOPO), based on a non-critically phase-matched KTA crystal driven by a diode-end-pumped acousto-optically Q-switchedNd:YVO4 laser, was demonstrated for the first time to our knowledge. With an absorbed pump power of 11.3 W, 1.1 W average power and 2.5 ns pulse width at the signal (1534 nm) wavelength for 30-kHz repetition rate are synchronously achieved with the 25 mm long KTA crystal. The corresponding peak power and single pulse energy are estimated to be up to 14.7 kW and 36.7 μJ. The conversion efficiency from diode laser power to OPO signal output power was 9.8% and the corresponding slope efficiency was 15.4%. PACS 42.60.Gd; 42.65.Yj; 42.55.Xi     

Littrow-type discretely tunable, Q-switched Nd:YAG laser around 1.3 μm

An all-solid-state, side diode array pulse pumped Nd:YAG laser tunable for six wavelengths ranging from 1318.8 nm to 1356.0 nm is developed. The tunability is obtained by using a grating in Littrow mode that also serves as an output coupler. The configuration ensures a line width as low as 0.04 nm. Thermal effects limit the maximum average power to 250 mW for an average absorbed pump power of 8.0 W in the free-running condition. An acousto-optic Q-switching of the laser provides pulses of width 251 ns with peak power of 733 W for an average pump power of 11.5 W. The laser may find application in microsurgery and dermatology. PACS 42.55.Xi; 42.60.-v; 42.60.Fc; 42.60.Gd; 42.62.Be     

Compact TEM<Subscript>00</Subscript> grazing-incidence Nd:GdVO<Subscript>4</Subscript> laser using a folded cavity

A compact diode-side-pumped Nd:GdVO₄ laser system using a folded cavity and grazing-incidence configuration is presented. The highest multimode output power obtained was 21.8 W at 36 W of effective diode pump power. Highest optical-to-optical conversion efficiency of 61.5% was achieved at 33 W of effective diode pump power with 20.3 W of multimode output power. For single-mode TEM₀₀ operation, an intracavity telescope was adopted for mode matching in the horizontal direction. Because of the folded cavity and the intracavity telescope, this laser head was the most compact to our knowledge of the TEM₀₀ grazing-incidence laser geometry. At last, an output power of 15 W was produced at 36 W of effective diode pump power. The stable Q-switching operation was also obtained. PACS 42.55.-f; 42.55.Xi; 42.60.Gd     

同轴-三平板型水介质脉冲输出开关实验研究

设计了用于脉冲功率装置的4 MV水介质同轴 三平板型输出开关。该脉冲功率装置将由24路相同的独立模块组成，每路模块由Marx发生器、中间储能器、激光触发气体开关、脉冲形成线、水介质脉冲输出开关、脉冲传输线等组成。水介质脉冲输出开关是同轴 三平板结构水介质多通道自击穿开关，由输入输出电极、预脉冲屏蔽板和连接部件组成。进行了有预脉冲屏蔽板结构和无预脉冲屏蔽板结构的自击穿水开关实验研究。有预脉冲屏蔽板结构开关的输入、输出电极都是半球电极，直径分别是8 cm和5 cm；无预脉冲屏蔽板结构开关为针 板结构，输入电极为平板电极，输出电极为直径3 cm的电极棒。Marx发生器充电70 kV，开关的击穿电压为3 MV，放电电流为450 kA。在3 MV等级的击穿电压下，有预脉冲屏蔽板结构开关的抖动约6 ns，没有预脉冲屏蔽板结构开关的抖动减小至3 ns。     

Axial mode tuning of a single frequency Yb:YAG thin disk laser

We describe an arrangement for an Yb:YAG thin disk laser, which enables narrow bandwidth operation in single-frequency mode at freely selectable wavelengths within the broad tuning range of the laser. This is facilitated by a combination of a double-stage birefringent filter and an etalon inside the laser cavity. We investigate the wavelength selection characteristics of the single elements as well as their combination. A simple procedure is implemented for a computer-based automation of wavelength tuning. The reflectivity of the partially reflecting resonator mirror is optimised, and the laser pump power is adapted for best tuning performance. Single-frequency emission is achieved in a frequency range of 9.75 THz (wavelength range 1020 nm to 1055 nm). Each axial laser mode in this range can be selected individually. The axial mode separation of 0.47 GHz corresponds to wavelength steps of 1.7 pm at 1030 nm. PACS 42.55.Xi; 42.60.Fc; 42.60.Lh     

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.     

2.5-GHz repetition-rate singly resonant optical parametric oscillator synchronously pumped by a mode-locked diode oscillator amplifier system

We report on an optical parametric oscillator (OPO) that is synchronously pumped directly by a diode laser. This laser is an actively mode-locked master-oscillator power-amplifier system that produces 20-ps pulses at 927 nm with a repetition rate of 2.5 GHz and an average power of 0.9 W. The OPO, which is a singly resonant device based on periodically poled lithium niobate, generates 7.8-ps pulses. The OPO threshold is 300 mW of average pump power, and the maximum average idler output power is 78 mW at a wavelength of 2100 nm. By changing the crystal temperature we can wavelength tune the output in the ranges 1530-1737 nm (signal) and 1986-2348 nm (idler). Rapid wavelength tuning of the OPO over 46 nm (signal) and 74 nm (idler) is achieved through tuning the cavity length over 28 microm by use of a piezoelectric transducer.     

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.     

Thin Nd:YAG slab laser pumped by lens duct coupled diode laser stacks

High power continuous wave operation of a diode face-pumped thin Nd:YAG slab laser is reported. A novel pumping geometry for a thin Nd:YAG slab using cylindrical lens duct coupled diode laser stacks is demonstrated. In a close-coupled resonator, a maximum laser output power of 260 W in multimode operation is obtained. This corresponds to a slope efficiency of 34% and an optical-to-optical efficiency of 27%, respectively. In high-brightness operation, a polarized laser output of 70 W has been obtained with a beam quality factor close to 4 in both directions. The polarization contrast ratio is >100. PACS 42.55.Xi; 42.60.Pk; 42.60.By     

808 nm高占空比大功率半导体激光器阵列

 采用渐变折射率分别限制单量子阱宽波导结构,通过降低非辐射复合、有源层载流子泄露、散射和吸收损耗来提高出射效率和降低激光阈值电流,从而提高半导体激光器阵列的输出功率;同时使P面具有更高的粒子掺杂数密度,优化N面合金条件,降低半导体激光器的串联电阻,降低焦耳热,提高了半导体激光器阵列的转换效率。利用金属有机化学气相淀积技术生长GaInAsP/InGaP/AlGaAs渐变折射率分别限制单量子阱宽波导结构激光器材料,利用该材料制成半导体激光线阵列在20%高占空比的输入电流下,半导体激光器的输出峰值功率达到189.64 W(180 A),斜率效率为1.1 W/A,中心波长为805.0 nm,阈值电流为7.6 A,电光转换效率最高可达55.4%;在1%占空比的输入电流下,阵列的输出峰值功率可达324.9 W(300 A),斜率效率为1.11 W/A,阈值电流为7.8 A,电光转化效率最高达55.6%,中心波长为804.5 nm。     

高占空比、高功率线阵二极管激光器封装技术

 对高占空比、高功率线阵二极管激光器的封装技术进行了研究,给出了封装器件性能测试结果：在占空比20%（200μs,1000Hz）时获得峰值功率大于40 W的激光输出,100～1000Hz 重复频率下,输出激光中心波长为 805～808 nm, 谱线宽度3.2～4.2 nm,激光起伏小于 1%。     

Online monitoring of ethane traces in exhaled breath with a difference frequency generation spectrometer

We report a transportable mid-infrared laser cavity leak-out spectrometer for online detection of trace gases. The laser spectrometer is based on continuous-wave difference-frequency generation in the wavelength region around 3 μm. Sensitive spectroscopic trace gas monitoring was achieved using a high-finesse ring-down cavity. For difference-frequency generation, we use a periodically poled lithium niobate (PPLN) crystal, pumped by a Nd:YAG laser (signal wave) and a diode laser (pump wave) with a tapered amplifier. A maximum power of 280 μW near λ=3.3 μm is achieved using a pump power of 180 mW at 807 nm, a signal power of 890 mW at 1064.46 nm, and a 50-mm-long PPLN crystal. The resulting system proved to be a unique tool with high sensitivity and specificity for rapid and precise breath testing. We demonstrate spectroscopic online monitoring of ethane traces in exhaled human breath with a precision of 270 parts per trillion (1σ) and a time resolution of 1 s. PACS 42.62.Be; 42.60.-v; 07.57.Ty     

Diode end-pumped 1123-nm Nd:YAG laser with 2.6-W output power

We present a compact and high output power diode end-pumped Nd:YAG laser which operates at the wavelength of 1123 nm. Continuous wave (CW) laser output of 2.6 W was achieved at the incident pump power of 15.9 W, indicating an overall optical-optical conversion efficiency of 16.4%, and the slope efficiency was 18%.     

High-power cladding-pumped Tm-doped silica fiber laser with wavelength tuning from 1860 to 2090 nm

A high-power double-clad Tm-doped silica fiber laser, pumped by two beam-shaped and polarization-coupled diode bars at 787 nm, was wavelength tuned by use of an external cavity containing a diffraction grating. The Tm fiber laser produced a maximum output power of 7 W at 1940 nm for 40 W of incident diode power and was tuned over a wavelength range of 230 nm from 1860 to 2090 nm, with >5-W output power over the range 1870-2040 nm. The prospects for further improvement in performance and extension of the tuning range are discussed.     

A polarization-stabilized microchip laser using a resonant grating mirror

A resonant grating mirror was monolithically integrated to an ytterbium-doped ceramic Y₃Al₅O₁₂ microchip laser to produce a linearly polarized laser beam emitting at 1030 nm with a polarization contrast ratio up to 1000. The device was pumped with a fiber-coupled laser diode bar emitting 2-ms pulses at 50 Hz at 940 nm. Up to 13-W peak output power was obtained from 20-W absorbed pump power at room temperature. The obtained slope efficiency with respect to the absorbed pump power was about 80%. PACS 42.40.Lx; 42.55.-f; 42.60.Jf; 42.60.Lh; 42.55.Xi; 42.70.Hj     

Laser performance of a broadband wavelength tunable Yb:germanophosphate glass with direct diode pumping

The laser performance of a new Yb:germanophosphate(Yb:GP) glass is investigated. A maximum output power of 826 m W at 1063 nm is achieved with direct diode pumping at 976 nm. The wavelength is tuned from 1034.47 to 1070.83 nm, corresponding to a tuning range of 36.36 nm. Thermal lens effects are investigated to optimize the optical cavity.     

High-repetition-rate, intracavity-pumped KTP OPO at 1572 nm

An efficient, eye-safe, high-repetition-rate, intracavity optical parametric oscillator (IOPO) inside an acousto-optically Q-switched Nd:YVO₄ laser end pumped by a 30-W fiber-coupled diode laser was demonstrated. The pumping, acousto-optically Q-switched Nd:YVO₄ laser gives 3-W average output power at 1064-nm wavelength at 40-kHz repetition rate. An additional separating mirror, x-cut KTP crystal and output coupler highly reflective at 1064-nm and partially transparent at 1572-nm wavelengths form a flat–flat IOPO resonator of 35-mm length. We have achieved 3-ns-duration pulses for 20-mm-long KTP and 4-ns-duration pulses for 30-mm-long KTP, respectively. More than 8-kW-peak-power pulses with an average power of 1.5 W at the signal wavelength for 40-kHz repetition rate were demonstrated. Due to the intracavity spatial cleaning effect, a near diffraction limited signal beam was achieved despite a relatively worse beam quality of the pumping beam. Conversion efficiencies of 50% with respect to Q-switched output at 1064-nm wavelength and 11% with respect to diode pump power were achieved. PACS 42.55.Xi; 42.60.Gd; 42.65.Yj     

All-solid-state 543 nm green laser generated by frequency doubling of a diode pumped Nd:YVO<Subscript>4</Subscript> laser at 1086 nm

An efficient and compact green laser at 543 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:YVO₄ laser at 1086 nm under the condition of suppression the higher gain transition near 1064 nm. With 10 W diode pump power and a frequency doubling crystal LBO, as high as 2.13 W of CW output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.3% and the output power stability in 3 h is better than 2.27%.