CHD/sub 2/OH optically pumped by a waveguide CO/sub 2/ laser: new far-infrared laser lines from the CD/sub 2/ wagging vibrational mode

For the first time, a wide tunability waveguide CO/sub 2/ laser was used to pump the CHD/sub 2/OH molecule for the generation of new FIR laser lines with a large offset. Optoacoustic signals associated with the infrared absorbing transitions of the CD/sub 2/ wagging vibrational mode served as a guide for finding new laser lines. All lines were characterized in wavelength, relative polarization, intensity, optimum pressure of operation, and precise offset measurements.     

Operating parameter optimization of optically pumped CH3OH far-infrared laser

By solving the density matrix equations of a quantum system, the output power intensity of an optically pumped CH₃OH FIR laser (CH₃OH-OPFIRL) was calculated by means of iteration method, and the spectral characteristics were got. Base on the calculation, optimization of operating parameters including operating gas pressure, pumped power and output coupling coefficient of the CH₃OH cavity laser were systematically studied. Experimental, a series of FIR emissions of the CH₃OH cavity laser pumped by TEA-CO₂ laser with 9P(16) line were measured. The experimental results were in good agreement with theoretical calculations.     

Characterization of new FIR laser lines from CHD/sub 2/OH

In this work, we report new optically pumped far-infrared (FIR) laser lines from CHD/sub 2/OH. A waveguide CO/sub 2/ laser of wide tunability (290 MHz) was used as pump source, and a Fabry-Pe/spl acute/rot open cavity was used as a FIR laser resonator. Optoacoustic absorption spectra were used as a guide to search for new FIR laser lines. We could observe 15 new laser lines in the range from 116.4 to 401.4 /spl mu/m. The lines were characterized according to wavelength, relative polarization, relative intensity, and optimum working pressure. The transferred Lamb-dip technique was used to measure the frequency absorption transition both for the new and previously reported laser lines.     

Methanol and the optically pumped far-infrared laser

New results on the generation and spectroscopic analysis of optically pumped far-infrared (FIR) laser emission from CH₃OH have been obtained as part of a systematic study of methanol isotopomers as FIR laser sources utilizing the extended line coverage available from a recently developed high-resolution CO₂ laser of high efficiency. For normal CH₃OH, six new short-wavelength lines have been found using a 2 m long Fabry-Perot FIR laser cavity. Accurate heterodyne frequency measurements are reported for 14 CH₃OH FIR laser lines, nearly all above 100 cm^-1, as well as accurate frequency offsets for most of the corresponding CO₂ pump lines. Spectroscopic assignments are presented for nine high-frequency FIR laser lines in four pump systems     

Frequency measurements of optically pumped far-infrared laser lines

In this work, we report the frequency measurements of optically pumped far-infrared (FIR) laser lines. We use the heterodyne technique of mixing FIR laser radiation and microwave radiation on a metal-insulator-metal (MIM) point contact tunnel diode, to determine the FIR laser frequencies. The two FIR laser systems, consisting of CO₂ waveguide pump lasers and Fabry-Perot FIR laser cavities, and MIM diode were developed by us. To check the system, we have measured some FIR laser line frequencies previously reported in the literature. An average fractional frequency reproducibility of ±7×10^-7, between our measurements and the previous ones, permit us to use our system to measure five new FIR laser frequencies     

Optical pumping of CHD/sub 2/OH and CH/sub 2/DOH methanol isotopomers by means of a new pulsed CO/sub 2/ laser: characterization of new far-infrared laser emissions

We have reinvestigated CHD/sub 2/OH and CH/sub 2/DOH methanol isotopomers as sources of far-infrared laser radiation using the optical pumping technique. A new waveguide pulsed CO/sub 2/ laser was used, that delivers high peak powers also in the 10-HP CO/sub 2/ band and has allowed us to observe 19 new far-infrared emissions from CHD/sub 2/OH and 8 new far-infrared emissions from CH/sub 2/DOH. Each of them is characterized in wavelength, pump offset from the center of the exciting CO/sub 2/ line, relative polarization, optimum operating pressure and intensity.     

Stark effect applicable to optically pumped far-infrared laser

The effect of low electric field Stark tuning on the absorption of CH3OH gas at theP(12) 9.4-muCO2laser line has been studied. At the 220-mtorr CH3OH pressure optimal for CH3OH far-infrared (FIR) laser operation, the line center absorption coefficient increases by a factor of 5 with a Stark field of 2.3 kV/cm.     

A review of optically pumped far-infrared laser lines from methanol isotopes

The technique of optical pumping in polar molecules is the most efficient for Far-Infrared (FIR) laser generation, providing also a versatile and powerful tool for molecular spectroscopy in this spectral region. Methanol (CH₃OH) and its isotopic varieties are the best media for optically pumped FIR laser, with over thousand lines observed, and the most widely used for investigations and applications. In this sense, it is important organize and make available catalogues of FIR laser lines as complete as possible. Since the last critical reviews of 1984 [1] on methanol and its isotopic varieties [2,3,4], over hundred papers have been published dealing with hundreds of new FIR laser lines. In 1992 a review of FIR laser lines from CH₃OH was presented [5]. In this communication we extend this work to the other methanol isotopes, namely CH₃OD, CD₃OH, CD₃OD,¹³CH₃OH,¹³CD₃OH,¹³CD₃OD, CH₃ ¹⁸OH, CH₂DOH, CHD₂OH and CH₂DOD.     

光泵浦远红外气体激光器的研究发展

远红外激光具有穿透性强、光子能量低、带宽宽、通信传输容量大等优点,在公共安全、环境探测、生物医学、天文观测、军事以及通信等方面得到了广泛应用。在介绍了远红外波段激光器发展的基础之上,对产生远红外激光的各种方式进行了对比分析和总结,讨论了光泵浦远红外气体激光器的技术优势,并针对近年来远红外激光工作介质及其新谱线进行了归纳。通过对连续和脉冲光泵浦远红外气体激光器发展的回顾,结合该领域的一些重点研究方向,给出了未来光泵浦远红外气体激光器的研究趋势。     

Characteristics of a far-infrared molecular laser optically pumped by a high-power CO2 laser

A molecular far-infrared (FIR) laser optically pumped by a high-power CO₂ laser, which is a powerful source for testing detectors and mixers and for FIR spectroscopy, is constructed and the performance is examined through experiments. At frequencies between 580GHz and 4.25THz, FIR output power is more than 20～30m W by pumping power of 35～81W. Amplitude stability of ±3% is obtained at 100m W output at 2.52THz for over 30 minutes when the FIR tube is cooled at 5°C by a chiller. As an application to testing mixers, FIR laser lines up to 4.25 THz are detected by Schottky barrier diodes (SBD). Further, using a SBD, performance of absolute frequency stability at 693GHz of HCOOH oscillation is measured by harmonic mixing with a 115.5GHz millimeter wave from a phase-locked Gunn oscillator. The resultant center-frequency stability is 100kHz per 10 minutes.     

光泵远红外激光的缓冲气体的选择因素

在半经典密度矩阵理论和SSH理论的基础上,理论研究了光泵远红外激光的缓冲气体作用,分析了势阱深度和碰撞半径两个参数对光泵远红外激光系统中缓冲气体作用的影响,从而得到选择缓冲气体的规律。研究成果对寻找小型光泵远红外气体激光器的高效缓冲气体,并推动其实际应用起一定的指导作用。     

Applications of high resolution spectroscopy to the identification of far-infrared laser emission from optically pumped13CH3OH

High-resolution infrared (IR) and far infrared (FIR) Fourier transform absorption spectra have been employed to investigate assignments of FIR laser lines reported from optically-pumped¹³CH₃OH. The spectroscopic measurements are used in conjunction with the reported IR pump and FIR laser frequencies to form closed combination loops for several systems, serving to confirm the assignments and in some cases to improve the accuracy of the FIR laser frequencies. Frequency predictions from combination differences are also presented for a number of potential new FIR laser lines.     

New optically pumped far-infrared lasers

Ninety-seven new far-infrared (FIR) laser transitions have been observed in optically pumped ethylene glycol, dimethyl ether, formic acid, and monomethyl amine, all excited by a pulsed CO2laser.     

On submillimeter laser lines from optically pumped12CH3OH

Several “new” submillimeter laser lines have been observed in a CH₃OH submillimeter laser, optically pumped by CO₂—laser radiation in a low power pulsed mode. Assignments have been suggested for a number of the lines. A few lines have wavelengths close to atmospheric water vapor absorption peaks, and can be observed only when the air path from the submillimeter resonator exit mirror to the detector is kept short or flushed with dry nitrogen.     

Spectra of optically pumped superradiant and cavity NH3 far-infrared laser

Based on the density matrix theory of quantum system, the spectra of optically pumped superradiant and cavity NH₃ far-infrared (FIR) lasers were calculated by means of iteration method. The calculation showed that, compared with the optically pumped superradiant FIR laser, the cavity laser had a wider band spectrum of FIR emission and a higher output power under certain condition, moreover, the spectra of cavity laser had multi longitudinal-mode structure.     

Gain of a CW optically pumped far-infrared laser with sandwich resonator

The FIR laser gain of CW optically pumped HCOOH was measured and compared to theoretical calculations. Since the laser has a transversely pumped parallel-plate (or “sandwich”) waveguide, the pump field is the same for oscillating and amplifying operation. Therefore, “true” FIR-gains were measured. The theory takes into account several phenomena, that are frequently simplified when considering FIR lasers, such as the pump and the FIR beam's spatial distribution, power broadening of the pump absorption, as well as heat and molecular diffusion. As a result, good quantitative agreement between theory and measurement was achieved.     

Assignments of optically pumped CD3OH laser lines

Six FIR laser lines from CD₃OH pumped by the 10R(36) and the 10R(18) CO₂ laser lines are assigned to specific rotational energy levels in the excited C?0 stretch state. It is found that their upper laser levels are shifted by a Fermi resonance between the C?0 stretch vibration and the third and forth harmonics of the torsional mode. The Fermi resonance shifts are +0.332 cm^?1 and +2.251 cm^?1 for the upper laser levels pumped by the 10R(36) and the 10R(18) CO₂ laser lines, respectively. Calculated frequencies of the pump and the laser transitions agree with those of the pump CO₂ laser lines and the observed FIR laser lines within estimated accuracy.     

The optically pumped far-infrared laser: Rate equations and diagnostic experiments

A four-level rate-equation model for an optically pumped far-infrared (FIR) laser is presented, and an expression is derived for the output power as a function of pump power and gas pressure. The theory is compared with measurements on the 570.5-μm line of CH3OH, pumped by a CO2laser. The width of the gain curve is measured and is shown to go below the Doppler width of the laser transition at low pressure. This indicates that the use of a monochromatic pump source leads to a velocity selective pumping process.     

Tunable far-infrared radiation from optically pumped potassium Rydberg transitions

We report the generation of tunable far-infrared radiation by the optical pumping of potassium metal vapor to the13p Rykberg state. Subsequent cascade by stimulated emission is measured at several wavelengths between 76 and 146 cm^?1 with a conversion quantum efficiency of greater than 10 percent. Emission observed in this region are tuned up to 18 GHz by the application of a pulsed Stark field across a parallel-plate heat pipe. Cascade branching to the 11d to 10f transition at 146 cm^?1 is observed which can be tuned up to 7 cm^?1 in our device. Similar branching following excitation up to the 18 p state is shown to provide almost complete tunability in the far-infrared region.     

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.