Optically pumped far-infrared emission in the cis 1, 2- difluoroethene laser

37 new far-infrared laser frequencies have been obtained in CO2laser excited cis 1, 2-C2H2F2, with several strong emissions in the terahertz region. Competing transitions have enabled assignments to be made to the v4and2v_{7}vibration bands.     

激光引信中发射单元的设计

本文设计了用于机载激光引信的激光脉冲测距发射单元,该发射单元由激光器和驱动电路构成.激光器选择纳秒级脉冲大功率固体激光器,采用半导体激光二极管作为泵浦源,提出了一种获取同步信号的方法,并对其整体结构进行了考虑.为满足引信特殊需要,为半导体泵浦固体激光器设计了专用驱动电路,解决了固体激光器在不同温度下重复频率不稳定性问题,避免了使用体积庞大的致冷器.激光发射单元工作可靠,在很大温度范围内重复频率稳定并灵活可调.5 V电源时,输出峰值功率达2 018 W、脉宽3.3 ns、重复频率达10 kHz.     

A quantum leap in laser emission

Medium- and long-haul, high-speed fiber communication systems are dominated by the need for low optical loss and low dispersion, and these systems require laser diodes and photodiodes that emit and detect at 1.33 and 1.55 μm. InGaAs/GaAs quantum dots enable 1.3 μm wavelengths in GaAs-based lasers for fiber-optic communication     

Complex pulse structure emission from a CO2hollow-cathode laser

A temporal analysis of CO₂ laser pulses generated in a hollow-cathode configuration is presented. A complex laser pulse structure from a single excitation pulse was detected, and the optimum CO₂-N₂ relation for maximum resonant energy transfer was determined. A mechanism responsible for the detected laser structure is suggested     

Far-infrared laser emission from H2CO in a large gas-laser tube

Far-infrared laser emission from H2CO in the sealed-off operation has been obtained with a large gas-laser tube. This emission has been observed from the beginning of discharge to several tens of pulses under pulsed electrical excitation. The emission lines were 102, 119, 122, and 159 μm.     

用等离子体电极产生紫外激光发射

我们研制了一种新颖的放电泵浦形式,即采用金属片间的放电产生等离子体即作为预电离又作为主放电电极。在N_2气中获得了均匀放电。 装置结构和电原理图如图1所示。金属片均采用1mm厚的钼片,制成锯齿形,每片长约1cm。两金属片放电间距为5mm。装配时,根据需要金属片数量可多可少,纵向金属片间距可密可疏。贮能电容C_0为64.8nF(2700pF×24)陶瓷电容器。每对金属片配一个电容量为780pF的小陶瓷电容器C_1。主放电电极间距为2cm。当球隙导通时,主贮能电容C_0放电,上电极和金属片间产生电压差,由于每对金属片配有一个电容器C_1,因此,在主放电回路导通之前,金属片之间首先放电对C_1充电。金属片的放电为主放电提供了良好的预电离条件,此时     

Deep red laser emission in Ho:YLF

Laser operation of the⁵S2→⁵I7transition in 2 percent Ho:YLF at room temperature is reported. Oscillations atlambda = 750nm were obtained in flashlamp and dye laser pumped experiments. Thresholds of 4 J/cm and3 times 10^{-4}J/cm were observed in flashlamp and laser pumped operation, respectively. The 750-nm transition in the Ho:YLF is a four-level laser with a stimulated emission cross section ofsigma = 9.7 times 10^{-19}cm².     

Correlation between laser emission noise and voltage noise in GaAs CW laser diodes

The cross-correlation coefficientc = | c | cdot e^{i vartheta}between the laser light noise and the diode voltage noise has been measured for three CW GaAs laser diodes at 77°K. A strong dependence ofcon laser diode current has been found.     

Efficient laser emission in concentrated Nd laser materials underpumping into the emitting level

The possibility of using concentrated Nd laser materials for efficient laser emission and for scaling to high powers is discussed. It is shown that the increased optical absorption in these materials makes direct pumping into the emitting level feasible, with a reduction of the quantum defect between the pump and emission wavelengths, which in turn can enhance the laser emission characteristics and reduce heat generation under pumping. The investigation of the effect of Nd concentration on emission decay of Nd:YAG indicates that up to quite high concentrations, the reduction of the emission quantum efficiency by self-quenching can be compensated by an increase in the pump absorption. Efficient continuous-wave laser emission is demonstrated under direct pumping into the ⁴F_3/2 emitting level of Nd:YAG crystals with up to 3.5-at.% Nd, Nd:YAG ceramics with up to 6.8-at.% Nd, and Nd:YVO₄ crystals with up to 3-at.% Nd. Superior performance as compared to traditional pumping into the ⁴F _5/2 state were obtained. It is inferred that direct pumping into the emitting level of concentrated Nd materials can improve the efficiency of solid-state lasers in the free-generation or low-storage regimes and opens the possibility of scaling these lasers to high powers     

Amplified spontaneous emission and carrier pinning in laser diodes

Theoretical and experimental results for the temperature dependence of amplified spontaneous emission (ASE) in laser diodes (LDs) and light-emitting diodes (LEDs) are presented. The theoretical model takes into account conduction band nonparabolicity and band-gap renormalization. The gain spectrum is calculated from the theoretical spontaneous emission spectrum, and both compare very well with experimental data. From a fit to the observed temperature dependence of ASE for an LED and the gain spectrum for an LD with a structure identical to that of the LED except for mirror reflectivity, it is possible to establish carrier density as a function of injection current for both devices. It is shown that photons fluctuating into cavity modes give rise to substantial subthreshold carrier pinning in laser diodes. These fluctuations extract an extra current from the device and play an increasingly important role with increasing temperature     

铜蒸气激光器中的放大自发辐射研究

图1是振荡-放大装置的示意图。振荡器和放大器均由平均输出功率为25W的铜蒸气激光器组成。放电管采用φ=35mm,ι=1100mm的陶瓷管。振荡器采用非稳腔输出,以保证放大器的注入光具有良好的方向性。用一台主脉冲信号发生器发出的信号同时控制二台或     

Far-infrared laser emission in gas discharges containing boron trihalides

Laser emission has been observed at 54 wavelengths between 11 and 41 μ in pulsed electrical discharges in BF3, BCl3, and BBr3. The emission wavelengths have been measured and the time behavior of the lines studied. Lasing in each of the gases produces total peak powers on the order of 10 to 100 mW. The addition of N2, He, or H2O to the discharge is found to have considerable effect on the peak powers of various lines and on the total energy emitted. The observed wavelengths are consistent with pure rotational transitions in HF, HCl, and HBr. Some short wavelength lines in the1.5-6 muregion are also observed but do not appear to be associated directly with the far-infrared emissions.     

线聚焦激光辐照靶时的离子发射特性

本文研究线状聚焦激光打靶时的离子发射特性.与点状聚焦时相比,线聚焦情况下离子发射的各向异性更为突出.当入射角α=22°时,离子信号明显比α=45°时所发射的信号大.这主要是共振吸收的结果.     

Simultaneous ultraviolet and infrared emission in asliding-discharge excited laser

Simultaneous laser action in the UV (337.1 nm and 357.7 nm) and the IR (2.6-3.1 μm) spectral ranges is observed in SF₆-N ₂-propane-butane mixtures directly excited by a sliding discharge. Output energies of 1.1 mJ in the ultraviolet and 12 mJ in the infrared are obtained simultaneously. Some performance parameters of the laser are presented     

Long-pulse laser emission from rhodamine 6G

The properties of the rhodamine 6G flashlamp-pumped circulating dye laser with cyclooctatetraene and cycloheptatriene as triplet-state quenchers are described. Particular attention is given to such observables as pulse duration, frequency sweep, and early termination of the laser pulse. From the experimental results and the theory of dye lasers, it is concluded that the thermal effects may not play a dominant role in such lasers.     

Spontaneous emission and gain in a waveguide free-electron laser

A free-electron laser (FEL) enclosed in a waveguide of narrowly spaced parallel plates has been proposed as a compact, coherent source of far-infrared radiation. The spontaneous emission and small-signal gain of such a device are analyzed. Maxwell's equations are solved for the fields of a relativistic electron beam passing through a linearly polarized undulator in the presence of a parallel-plane waveguide. The radiation intensity is resolved into its component waveguide modes for the fundamental frequency and for all harmonics. The intensity profile in a given harmonic mode is altered significantly when a parameter involving the undulator period, beam energy, and transverse dimension of the guide is such that the radiation group velocity is close to the electrons' axial velocity. The small-signal gain in the waveguide FEL is calculated and related to the spontaneous emission. Near zero slip, the gain curve is significantly different from that of a free-space FEL with the same parameters     

Near-field emission from GaAs double-heterostructure laser mirrors

The near fields of GaAs double-heterostructure (DH) laser mirrors are studied both in photoluminescent (PL) excitation and in lasing emission. The various liquid-phase-epitaxial (LPE) layers of the laser diode are optically delineated, withmp0.1-mum resolution, in a wavelength-selective PL detection system. The near fields of the transverse lasing modes are correlated with the LPE layers that constitute the optical waveguide. With special emphasis on the large-cavity fundamental-mode Ppn'N laser, it is found that small changes in refractive index within the waveguide have pronounced effects on the distribution of stimulated power within the LPE layers. The fundamental mode is found to be contained within the slightly higher refractive-index gain region. This explains the previously observed localization of catastrophic mirror damage and the anomalously large angles of beam divergence. High-order modes are also excited in the gain region when its thickness and refractive-index step within the waveguide exceed some prescribed limits.