High repetition rate CH4 laser

A 16-m CF₄ laser oscillator has operated at 1 kHz in a cooled static cell. Pump energies required from the low pressure, Q-switched, cw discharge CO₂ laser were as low as 60 J. The laser cavity employed a multiple-pass off-axis path resonator in a ring configuration. CF₄ laser power at 615 cm^–1 and a 1-kHz repetition rate exceeded 300 W.     

Waveguide CW 118.6 μm H2O laser

This paper reports results of an experimental study of a cw 118.6 m H₂O waveguide laser. The laser cavity is a 3 cm inner diameter, 3.2 m long Pyrex tube, with plane reflectors against its ends, one of them being a copper mesh coupler. The active medium is a H₂O:H₂ gas mixture. Successive optimizations lead to a reliable output power of 50 mW, for the EH₁₁ mode. The power density is the highest ever reported, and the stability is such that the power drifts by less than 2% per hour. This laser is competitive with the optically pumped 118.8 m CH₃OH laser.     

The Optimum Operation of an Unified Mini-Optically Pumped NH3 Submillimeter Wave Laser

An unified miniature optically pumped NH₃ submillimeter wave laser (OPSMMWL), including a mini TEA-CO₂ pump laser, was developed. It lased successfully with coherent emission at 67.2m, 90.4m and 151.5m. The optimum operation of the unified mini-OPSMMWL was studied experimentally and the relations among SMMW laser output power, operating gas pressure, length and coupling condition of the cavity were measured. It has been found that buffer gas N₂ has significant effect on 67.2m and 151.5m emissions and very wide band SMMW laser emission was a common feature of the mini-OPSMMW cavity laser.     

Effects of Buffer Gas N2 on Miniature Optically Pumped NH3 Submillimeter Wave Cavity Laser Emission at 67.2 μm

The effect of buffer gas N₂ on miniature optically pumped NH₃ submillimeter wave (SMMW) cavity laser emission at 67.2m was studied theoretically and experimentally. It has been found that: 1. N₂ had a positive effect on laser output of 67.2m, 2. sharp absorption in laser spectrum under certain gases mixture pressure corresponded to the threshold of 'bottleneck effect.     

Six-Watt mid-infrared laser using harmonic generation with Tl3AsSe3

An output of 6 W at 30 kHz was achieved using Tl₃AsSe₃ as the nonlinear second-harmonic generator. It was pumped with a CO₂ laser source at a wavelength of 9.25 m with 20 ns pulses, and the laser beam was focussed to a spot size of 150 m. The focussed spot was scanned to reduce the continuous-wave power loading, and the system could be operated for extended periods of time under these conditions.     

CW Discharge‐Pumped DCN Laser with Novel Mixture Gas

This paper describes a CW submillimeter waveguide dischargepumped DCN laser operating on 190 and 195m lines with novel mixture gas(N₂, CD₄, and D₂). No brown polymer deposit was found after long time discharge even at low wall temperature. The laser discharge length is 3 m, and the resonator length is 3.4 m. The resonator cavity consists of a pyrex tube of 54 mm diameter and two plane reflectors against its ends, one is a plane mirror, the other is a metal mesh. After optimization of various parameters, such as the N₂:CD₄:D₂ gas mixture, the discharge current and the wall temperature, this laser delivers 150 and 160mW on the 190 and 195m lines, respectively, for EH₁₁ mode.     

Compact, high power FIR NH3 laser pumped in a three mirror CO2 laser cavity

A compact CO₂–NH₃ FIR laser system where an NH₃ laser cavity was inserted in pump, three mirror CO₂ laser cavity was designed. The total length of this system was about 1.8 m. Output energy of about 1 mJ (10 KW pea power) was obtained at the 152 m and 90 m lines in NH₃. Power conversion efficiency of 1.7 percent was obtained at the 90 m line.     

Simultaneous two wavelength operation of an optically pumped HCOOH laser on orthogonally polarized modes

Simultaneous laser operation in orthogonally polarized EH₁₁ and TE₀₁ waveguide modes is reported for pairs of cascade lines from an optically pumped formic acid vapour laser incorporating a strip grating output coupler. Observations were made for the 394 m/406 m and 433 m/446 m cascade sequences, the resonator length being adjusted so that the laser was simultaneously resonant on a mode of the primary transition polarized perpendicular to the strips of the output coupler and the same transverse mode of the secondary transition polarized parallel to the coupler strips. Power measurements showed that for the laser configuration used in this study the power of the primary transition was increased only slightly when the cascade lines were simultaneously resonant, whereas the secondary line could only lase under these conditions.     

Frequencies and wavelengths from a new, efficient FIR lasing gas: CD2F2

We report for the first time wavelength, relative polarization, and frequency measurements for 47 new cw FIR laser lines in the wavelength region from 120 to 1714 m, all obtained by optically pumping CD₂F₂ with a CO₂ laser. Relative output powers were also measured. For comparison, the 189.8 m line pumped by R_I(34) is nearly five times as efficient as the 118.8 m methyl alcohol line.Contribution of the U.S. Government, not subject to copyright.     

Diode-pumped cw and Q-switched Nd:GdVO4 laser operating at 1.34 μm

A diode-pumped 1.34 m Nd:GdVO₄ laser operating in cw and active Q-switching modes has been demonstrated. 4.15 W of cw output power was obtained at the highest attainable pump power of 12.3 W, resulting in an optical conversion efficiency of 33.7%, the slope efficiency was determined to be 37.6%. In Q-switching operation, a maximum average output power of 2.7 W was generated at pulse repetition frequency (PRF) of 50 kHz, with an optical conversion efficiency of 22% and a slope efficiency of 29.2%. The laser pulses with shortest duration, highest energy and peak power were achieved at PRF of 10 kHz, the parameters being 15 ns, 160 J, and 10.7 kW, respectively. By intracavity frequency-doubling with a type II phased-matched KTP crystal, 0.62 W average power at 0.67 m was produced at a PRF of 15 kHz, the resulting pulse energy, peak power, and pulse width being 41.3 J, 2.2 kW, and 19 ns, respectively. A group of analytical formulae, based on rate equations, are presented to evaluate the operational parameters of an actively Q-switched laser. Calculated results were found to be in close consistency with the experimental data.