Mid infrared and far infrared studies of the propyne optically pumped laser

An extensive study of the propyne optically pumped laser is presented. 32 new far infrared and 8 new mid infrared outputs are reported, together with pump frequency offset data. Complete assignments of some far infrared transitions and partial assignments of the mid infrared outputs are given. Very strong interactions occur between the mid and far infrared laser transitions. These interactions are of vital importance in obtaining high output energies.     

Nonlinear level crossing in the infrared transitions of optically pumped far infrared laser media

In conjunction with the Stark field induced power enhancement in optically pumped far infrared lasers, absorption transitions in a degenerate two level system under the influence of an weak static Stark field have been analyed. A third order theory to the density matrix formalism leads to zero field level crossing signals for absorption in rate equation approximation and in Doppler limit. For fast relaxation among Zeeman sublevels, the zero field level crossing signal arises from population effect. Optoacoustic measurements have been carried out on the ν₅,^qQ(16,8) absorption line of CH₃OH which produces the familiar 119-μm laser with the CO₂ 9P(36) pump line. The optoacoustic absorption signals observed are well reproduced by the theoretical expression.     

The vinyl bromide optically pumped far infrared laser: new largeoffset emissions

We present the results of a study on vinyl bromide in the search for new far infrared (FIR) laser lines. As the pump source, we use a CW waveguide CO₂ laser with a tunability of 290 MHz around each line in order to pump large offset vibrational transitions. As a consequence, we obtained 28 new FIR laser emissions; 24 of them have wavelengths greater than 500 μm and are, therefore, suitable to be used in high-field EPR spectroscopy. For each of the new lines, we give the wavelength, the offset of the pumping transition with respect to the center frequency of the CO₂ emission, the polarization relative to that of the pumping laser line, the operating pressure, and the relative intensity. We also present a catalog including data of all of the FIR laser lines observed from this molecule up to now     

光抽运甲基氟远红外激光器

一、引言 用CO_2激光抽运的远红外激光器诞生在1970年,至今已在30多种分子中获得了1000多条远红外激光谱线,波长范围从40微米到2毫米,复盖了整个远红外区。与电激励远红外激光器相比,光抽运的远红外激光器不存在放电起伏、热漂移和分子分解等现象。因此,具有单色性好,噪声低等优点,特别适用于通讯、雷达、等离子体诊断、光频标与光频测量、光谱学、天文学等领域。     

A variable reflectivity output coupler for optically pumped far infrared lasers

In this paper we describe the design and performance of a variable reflectivity output coupler for optically pumped far infrared (FIR) lasers. The output coupler is a compact, tunable Michelson interferometer. The output coupling ratio (i.e. the Michelson transmission) is adjustable between 0 and ≥60% for laser line wavelengths between 110 and 500 μm. This output coupler provides increased output power and flexibility, since it can be tuned to optimum coupling ratio for different laser lines. Beam profile measurements show that the Michelson output coupler produces a well collimated Gaussian laser beam. Design features are a) the use of 10 μm reflection coated quartz vacuum window which acts as a dichroic mirror for the pump radiation and b) the high mechanical stability obtained by a leaf spring flexure mount of the movable Michelson mirror and by restricted alignment devices.     

A new stabilization system for optically pumped cw far infrared lasers

A new type of stabilization system for optically pumped far infrared (FIR) lasers based on a dual modulation technique is described, which enables to control the laser output power both as a function of the CO₂-laser pumping frequency and the FIR laser cavity length. The system greatly improves the laser output stability and causes only a negligible modulation (<1 %) of the output power. An additional feature, an electronic search circuit for emission lines, simplifies working at the laser even by ineperienced people.     

Buffer gases to increase the efficiency of an optically pumped far infrared D2O laser

The effects of buffer gas additives on the performance of an optically pumped D2O laser operating at 385 μm have been investigated both experimentally and by numerical simulation. Three gases, sulphur hexafluoride, carbon tetrafluoride, andn-hexane, were found to produce an increase of up to 40 percent in the pumping efficiency, as well as significant lengthening of the far infrared pulse. Under optimum conditions, 2.6 J in a 1 μs long pulse have been obtained. The buffer gases are shown to eliminate the vibrational deexcitation bottleneck, which in pure D2O leads to an accumulation of population in the upper vibrational leve and, hence, a reduction in the efficiency of absorption of the pump beam. Comparison of the observed buffer gas effects with the predictions of a numerical simulation code based on a rate equation model gives information about the constants for vibrational and rotational relaxation rates due to D2O-D2O and D2O-buffer gas collisions.     

Frequency measurements of far infrared cw lasing lines in optically pumped CHCl2F

The wavelengths, frequencies, and relative polarizations of 15 FIR cw lasing lines obtained by optically pumping CHCl₂F with a cw CO₂ laser have been measured. The lines are in the wavelength range from 340.3 to 905.4 μm and were pumped by P- and R-branch laser lines in the 9 μm band of CO₂.     

Instabilities in optically pumped infrared lasers

The unstable emission of an optically pumped FIR gas laser is theoretically analysed through numerical resolution of the associated Maxwell-Bloch equations. The instability domain in the main control parameters space is determined and an example of chaotic behaviour is examined.     

The optically pumped ozone laser

We report here the CW observation and the assignment of 7 lines of¹⁶O₃ pumped by a CO₂ laser. The frequency measurement of one line of¹⁸O₃ has also been obtained.     

High power mid-infrared optically pumped PbSe/PbSrSe multiple-quantum-well vertical-cavity surface-emitting laser operation at 325 K

A high power, mid-infrared (/spl lambda/=3.8 /spl mu/m) lead-salt vertical-cavity surface-emitting laser (VCSEL) operating at 325 K is demonstrated. The laser emission is generated in a half-wavelength microcavity consisting of seven pairs of PbSe/PbSrSe multiple-quantum-wells embedded in two mirrors and optically pumped with 5 ns laser pulses.     

Frequency-tunable optically pumped carbon monoxide laser

Single-line frequency-tunable lasing was observed in an optically pumped, repetitively pulsed, room-temperature CO laser for the first time. The R(0) and R(7) ro-vibrational transitions in the (2,0) overtone of CO at 2.3 μm were optically pumped with a high-energy optical parametric oscillator. Single-line lasing was observed on (2,1) P(2)-P(17) transitions and R(0)-R(11) transitions (covering wavelengths within the range 4.6-4.9 μm) when using a diffraction grating as the spectrally selective reflector of the laser resonator. The observed CO laser pulse lengths were ~10^-7 s with peak power up to 10⁴ W. The influence of CO pressure, the addition of buffer gas (He, Ar), Q-factor of the laser resonator, and the pump pulse energy on CO laser pulse temporal characteristics and output energy spectral distribution was studied experimentally     

Analysis of CH3OH far infrared laser lines optically pumped by sequence band and isotopic CO2lasers

Assignments are presented for seven far infrared (FIR) laser lines of CH3OH pumped by theS-9P(31),18-10R(24),13-9R(26), and13-9P(16)CO2laser lines, plus an interesting speculation for the FIR line pumped by the18-9P(12)CO2line. Frequencies have been deduced to a substantially improved accuracy of ±0.001 cm^-1from IR and FIR spectroscopic combination differences for most of the assigned lines as well as three other predicted transitions. In addition, accurate frequencies are given for 13 predicted FIR laser transitions which are expected from the IR spectrum to be pumped by three¹⁶O¹²C¹⁸O laser lines.     

Study of the saturation effect and output power of optically pumped FIR laser

In this paper, the density matrix equation of a six-level system has been solved, in case of the FIR wave signals in the system were not small enough to be neglected. The output power density of the laser system has been calculated by means of the iteration method. The saturation effect of the system has been revenled by the numerical calculation. Several sets of curves of laser output power vs, the length of laser with defferent pumping detuning and the optimum operating pressure under certain condition have been obtained. These calculated values were in good agresment with the data provided in the literatures.     

A tunable far infrared laser

A continuously tunable far infrared (FIR) laser has been demonstrated; experimental results are presented. A high-pressure (10-12 atm) continuously tunable CO2TE laser is used to pump Raman transitions in CH3F; the generation of continuously tunable radiation in the250-300 mum wavelength range is reported. Accurate frequency and bandwidth measurements have been made and the FIR bandwidth in superradiant emission isapprox4-5GHz. Consequently, the generation of frequency tunable, subnanosecond pulses in the FIR appears feasible. The generation of tunable laser radiation from 150 to 1000 μm by stimulated Raman scattering should be possible using higher pump intensity and/or other gases.     

Near ultraviolet optically pumped vertical cavity laser

Optically pumped near ultraviolet vertical cavity laser operation (VCSEL) has been obtained under quasi-continuous wave conditions at room temperature near 383 nm from shallow InGaN/GaN multiple quantum wells (MQWs). Low loss optical resonators were fabricated by using in-situ grown (Al,Ga)N distributed Bragg reflectors that featured strain engineering design for high optical morphology, in combination with low-loss dielectric multilayer mirrors     

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     

Single-mode semiconductor laser optically pumped by an injection laser

Nanosecond pulses from an AlGaAs injection laser have been used to optically pump an ultrashort-cavity InP laser. Subnanosecond pulses from the InP laser exhibit a single longitudinal mode at 0.92?0.93 ?m.