序列脉冲激光产生的光压及其对原子束的冷却与减速效应

本文通过解双能级系统的密度矩阵方程,求出了序列脉冲激光的光压力,计算了光压对原子速度分布的影响,并与连续激光的作用进行了对比。结果表明:采用序列脉冲激光并适当选择调制函数参数,可比相同功率甚至功率增大1/2情况下的连续激光更为有效地使原子束减速和冷却。     

Fast plasma mixing--A new excitation method for CW gas laser

"Fast plasma mixing" is proposed as a method to generate population inversions on electronic transitions for continuous lasers. Selective excitation is accomplished by preparing collision partners for excitation in two or more separate beams. Excitation in a well-defined reaction volume and a fast flow in combination with a suitable resonator will allow the fast removal of decay products from the active volume. This pumping method will allow the operation of new CW laser systems not possible with conventional discharges and CW operation of laser systems, which at this time can only be operated as pulsed lasers. A test device has been used to study the proposed excitation method. CW operation as a fluorine laser has demonstrated the general feasibility of this method. Of special interest are molecular lasers pumped by charge or energy transfer from atomic species or by chemical reactions and excimer lasers. These lasers may offer the capability of operating CW tunable gas lasers in the visible and ultraviolet spectral regime.     

Cd recombination laser in a plasma generated by an electron beam

Laser action was obtained in the 1.40, 1.43, and 1.65 μm lines of CdI following electron-ion recombination in a plasma generated by an electron beam. Lasing does not occur during the excitation pulse due to the electron impact population of the laser lower levels. In this plasma, supercooling of the electrons is achieved under stationary conditions, and efficient CW recombination laser action might also be possible on lines in which the lower level is not significantly populated by electron collisions. Seven new infrared laser lines in CdII are also reported.     

电激励连续波HF/DF激光器放电参数的优化

放电管作为电激励连续波HF/DF激光器的F原子发生器,在整个激光器系统中占有重要地位。目前流行采用的是高压直流电源加镇流电阻的放电模式,典型电参数为接近10kV高电压、百毫安量级的低电流。传统理论和实验结果均认为:放电管F原子产率与放电管注入功率成正比,从而激光器输出功率也应与之成正比。引入不同阻值的镇流电阻,发现对于相同的注入功率,低电压、大电流模式比高电压、小电流模式更容易获得高的功率输出。     

Zn II and As II CW laser transitions excited by an electron beam

CW laser action was obtained on the 4911.6, 4924.0, 6102.5, and 7588.5 Å transitions of Zn II and on the 6511.7 Å transition of As II using electron beam excitation of He-Zn and He-As mixtures, respectively.     

Compact Hg II laser excited by a transverse electron beam glow discharge

CW laser action at an output power of 6 mW has been obtained on the 6149.5 Å transition of Hg II, using a 10 cm long transverse electron beam glow discharge. Beam energies are typically 1 keV. Laser tube design, discharge characteristics, and laser output power are reported.     

CW laser oscillation at 6127 Å in singly ionized iodine

CW laser action has been obtained on the 6127-Å transition ofI(II) in a He-CdI2discharge. Relative output power has been measured as a function of discharge current, helium pressure, and CdI2temperature.     

New efficient CW far-infrared optically pumped CH2F2laser

Far-infrared laser action is reported for the first time from the optically pumped CH2F2molecule. Lasing on twelve FIR transitions was produced by pumping with six emission lines in theRbranch of the 9.6 μm band of the CW CO2laser. High conversion efficiencies of up to 20 percent of the quantum limit have been obtained with the stronger FIR laser lines.     

Low-threshold continuous-wave 1.5-/spl mu/m GaInNAsSb lasers grown on GaAs

We present the first continuous-wave (CW) edge-emitting lasers at 1.5 /spl mu/m grown on GaAs by molecular beam epitaxy (MBE). These single quantum well (QW) devices show dramatic improvement in all areas of device performance as compared to previous reports. CW output powers as high as 140 mW (both facets) were obtained from 20 /spl mu/m /spl times/ 2450 /spl mu/m ridge-waveguide lasers possessing a threshold current density of 1.06 kA/cm/sup 2/, external quantum efficiency of 31%, and characteristic temperature T/sub 0/ of 139 K from 10/spl deg/C-60/spl deg/C. The lasing wavelength shifted 0.58 nm/K, resulting in CW laser action at 1.52 /spl mu/m at 70/spl deg/C. This is the first report of CW GaAs-based laser operation beyond 1.5 /spl mu/m. Evidence of Auger recombination and intervalence band absorption was found over the range of operation and prevented CW operation above 70/spl deg/C. Maximum CW output power was limited by insufficient thermal heatsinking; however, devices with a highly reflective (HR) coating applied to one facet produced 707 mW of pulsed output power limited by the laser driver. Similar CW output powers are expected with more sophisticated packaging and further optimization of the gain region. It is expected that such lasers will find application in next-generation optical networks as pump lasers for Raman amplifiers or doped fiber amplifiers, and could displace InP-based lasers for applications from 1.2 to 1.6 /spl mu/m.     

Frequency locking in double-pumped dye laser

A jet-stream dye laser was pumped simultaneously by a CW argon laser and a high-power xenon ion laser. The frequency and bandwidth of the pulsed radiation obtained were locked to the CW radiation inside the folded cavity.     

A Q-switched diode-pumped neodymium yttrium aluminumborate laser

A report is presented on the first Q-switched laser operation of a room temperature CW diode-pumped Nd:YAB laser. The intense peak fundamental power obtained by Q-switching significantly enhances the green light output from the Nd:YAB laser through the second harmonic conversion process. A peak green power exceeding 3 W was obtained with a CW diode laser input power of 180 mW, as compared to a green output power of only about 1 mW under pure CW operation. Nd:YAB shows considerable promise as a room temperature self-doubling material. Diode-laser-pumped Nd:YAB lasers show promise as compact, and reliable green sources for practical applications     

1.3 µm high-power BH laser on p-InP substrates

In our fabrication of a 1.3 μm band high-power BH laser on a p-type InP substrate, 79 mW CW laser output was obtained, and the spectrum width was 10 nm at 50 mW; it also obtained a high-power pulse output of more than 200 mW at 30 ns pulse width. It shows high-speed pulse response at 2 Gbits/s. These CW and pulse lasing characteristics are reported in this paper, and we also show the output and threshold current distribution of about 1000 samples from six wafers. This high-power laser is very useful for light sources of measuring instruments.     

连续腔内倍频拉曼激光器的归一化理论解析

腔内倍频拉曼激光器是获得黄光激光光源的重要途径,目前尚未有直接的表达式描述连续腔内倍频激光器的功率输出对抽运和激光器参数的赖关系。以速率方程为基础,对腔内倍频连续拉曼激光器的理论模型进行归一化处理,得到平面波近似下连续腔内倍频拉曼激光器的归一化速率方程组。对此方程组进行求解,得到描述激光器输出的表达式各变量以及参量与输出变量之间的归一化表达式,根据表达式获得了描述激光器运行的理论曲线。     

Comparison of two new microwave plasma sources for HF chemical lasers

The performances of two microwave sources used to produce fluorine atoms by dissociation of SF6for a CW hydrogen fluoride chemical laser are compared. The first device, large microwave plasma (LMP), is a slow-wave structure while, the other (surfatron) excites a plasma surface wave. Their performances, as far as electrical and chemical efficiencies are concerned, are quite similar when operated at the same microwave power level. However, the slow-wave structure can sustain higher microwave power, providing larger laser output power, while the surfatron has much smaller dimensions, allowing for a more compact laser system.     

Tunable CW alexandrite laser

Wavelength-tunable CW laser action has been obtained from solid-state alexandrite, BeAl2O4:Cr³⁺. Laser emission occurred between 744 and 788 nm with a maximum of 6.5 W observed at the 765 nm wavelength with 3 kW of mercury arc excitation.     

Linearly polarized polarization-maintaining Er3+-doped fluoride fiber laser in the mid-infrared

We demonstrated the ~2.8-μm and ~3.5-μm linearly polarized continuous wave (CW) laser outputs from a polarization-maintaining (PM) Er3+-doped fluoride fiber laser. By introducing a film polarizer into the cavity to select the laser polarization orientation, the ~2.8-μm linearly polarized CW laser with a high polarization extinction ratio (PER) of ~23 dB and maximum output power of 2.37 W was achieved under double-end pumping at 976 nm. By adding another 1981-nm pump source simultaneously, the ~3.5-μm linearly polarized CW laser was also obtained, giving higher PER of ~27 dB and maximum output power of 307 mW which is only limited by the available power of 1981-nm pump. To the best of our knowledge, this is the first report on a mid-infrared linearly polarized CW PM fiber laser in the >2.5-μm mid-infrared region. This work not only opens up opportunities for some new mid-infrared applications, but also provides a promising platform for developing high-stability and versatile mid-infrared laser sources.     

LD端面泵浦946 nm/473 nm连续Nd:YAG/LBO激光器

对Nd:YAG 946 nm和 473 nm激光器特性进行了实验研究。采用二极管端面泵浦平-平腔实验结构,使用键合Nd:YAG晶体作为激光增益介质,在入射泵浦功率31.8 W时,得到最高11 W的连续波946 nm 激光输出,光-光转换效率34.6%,斜率效率35.4%,光束质量M2达到7.53,半小时内功率不稳定度小于0.4%。采用Ⅰ类临界相位匹配LBO晶体对946 nm激光进行内腔倍频,获得了0.887 W的连续波473 nm蓝光输出,光-光换转效率5.87%。实验结果表明:所设计的端面泵浦连续激光器具有很强的实用价值。     

Room-temperature CW operation of 1.60 ?m GaInAsP/InP buried-heterostructure integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide

CW operation of a 1.60 ?m GaInAsP/InP buried-heterostructure integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide (BH BJB DBR integrated laser) was achieved at room temperature. Single longitudinal-mode operation at fixed mode was obtained in a temperature range of about 60 deg C, under the CW condition, and it was also maintained under rapid direct modulation of 1.6 GHz.     

Mid-infrared fluoride fiber lasers in multiple cascade operation

CW fiber laser cascades in an Er³⁺-doped fluorozirconate fiber operating simultaneously at 2.7 μm/1.55 μm or at 3.45 μm/2.7 μm/1.55 μm pumped around 650 nm are reported. Output powers of nearly 20 mW at 1.55 μm and 1.2 mW around 2.7 μm were obtained with a nonoptimized experimental setup for the 2.7 μm/1.55 μm cascade. At 1.55 μm a laser efficiency of 5% was achieved. By varying the parameters of the experimental setup, additional effective simultaneous laser action at 3.45 μm was demonstrated     

Short pulse generation by use of an active multipass interferometer

The operation of a simple device that converts continuous-wave (CW) laser light into a short-pulse train is reported. The setup is based on a passive ring cavity in which an acoustooptic frequency shifter takes the place of one of the mirrors. Temporal filtering and pulse compression of laser light was demonstrated. The experimental results obtained by injecting a CW CO₂ laser light in such a device are in agreement with the theoretical analysis. The device's application in external pulse compression of mode-locked pulses is also demonstrated