Far infrared laser frequencies of 13CD3OH

We have measured 30 far-infrared laser frequencies of optically pumped ¹³CD₃OH, 13 of which are new lines. The frequencies range from 0.5 to 4.9 THz with the majority between 0.75 and 1.5 THz. Two frequency stabilized CO₂ lasers were used as standards for the heterodyne measurements     

New short-wavelength laser emissions from optically pumped 13CD3OD

We report the discovery of 15 new laser emissions from ¹³ CD₃OD when optically pumped with a CW CO₂ laser. The wavelengths of these lines, ranging from 57.5 to 135.2 μm, are reported along with their polarization relative to the CO₂ pump laser, operating pressure and relative intensity. A three-laser heterodyne system was then used to measure the frequencies of 12 optically pumped laser emissions from this methanol isotope. These emissions range from 65.7 to 151.8 μm and are reported with fractional uncertainties up to 2·10^-7     

The 13CH3OH optically pumped far-infraredlaser: new lines and frequency measurements

We report 18 new laser lines from ¹³CH₃OH generated in an optically pumped far-infrared laser; the laser lines are in the range of 54.2-420 μm and are all characterized in wavelength, polarization relative to the pumping CO₂ radiation, and pump offset relative to the CO₂ center frequency. The frequencies of seven of these new lines along with 10 previously reported lines were measured by an accurate heterodyne technique, mixing them in a metal-insulator-metal (MIM) point contact diode, with another laser line of known frequency     

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。     

13CD3OD optically pumped by a waveguide CO2 laser: new FIR laser lines

A waveguide CO₂ laser of wide tunability was used to pump infrared transitions of the ¹³CD₃OD C-O stretching vibrational mode. The optoacoustic signal associated with the absorbing transitions served as a guide to search for new laser lines. We could observe 36 new far-infrared laser lines ranging from 57 to 1192 μm. All lines were characterized in wavelength, relative polarization, intensity, optimum pressure of operation, and precise offset measurements     

Narrow bandwidth emission from a mirrorless, far infrared, 13CH3F laser

Frequency tuning and linewidth measurements are reported for a pulsed, mirrorless, kilowatt-power-level, far-infrared (FIR) ¹³ CH₃F laser operating at 245 GHz. The pump laser is an etalon tunable, single-mode CO₂ TEA laser. The FIR frequency spectrum was measured with 2.5-MHz resolution on individual 100-ns laser output pulses using harmonic mixing techniques. The linewidth of the amplified spontaneous emission was found to be surprisingly narrow, about 15 MHz. Frequency tuning of the FIR laser, as the pump laser frequency is tuned, is nonlinear, possibly due to inhomogeneous broadening of the gain by the K-level substructure of the rotational states. These results indicate that heterodyne receivers capable of single-shot frequency measurements can be important tools for investigating the properties of Raman FIR lasers     

Observation and assignment of D218O FIR laserlines optically pumped by a waveguide CO2 laser

By means of a detailed analysis of the v₂ infrared band of D₂¹⁸O, it has been possible to assign most of the FIR emissions reported in the literature. Moreover, two FIR laser lines which fall in the range of tunability of the CW waveguide CO₂ laser have been predicted and observed. The frequency of the stronger line was measured and found to be 2611.4185(10) GHz, thus filling a gap in the presently available comb of FIR laser lines whose frequencies have been measured. The wavelength precision of the assigned lines was improved by about two orders of magnitude     

Characterization of new FIR laser lines from CD3-rockingand asymmetric CD3 deformation modes of 13CD3OD

In this paper, we report new optically pumped far-infrared (FIR) laser lines from the in-plane CD₃-rocking and asymmetric CD ₃ deformation absorption vibrational bands of ¹³CD ₃OD. A waveguide CO₂ laser of wide tunability (290 MHz) was used as the pump source, and a Fabry-Perot open cavity as the FIR laser resonator. Optoacoustic absorption spectrum was used as a guide to search for new FIR laser lines. We could observe 13 new laser lines in the range 103-491 μm. 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 for both new and previously reported laser lines     

New far infrared CW optically pumped cis-C2H2F2laser

Lasing on 6 FIR lines is reported for the new laser molecule cis-C2H2F2with high conversion efficiencies up to 7 percent of the maximum theoretical limit. A set of molecular selection criteria was used to predict efficient FIR lasing from this molecule, and analysis of the laser performance has increased the basic understanding of the molecular parameter contribution to high conversion efficiency. From this work a refined set of selection criteria has evolved that may be used to predict additional efficient laser molecules.     

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.     

可调谐光泵CF_4激光器

图1是简化的实验装置。泵浦源采用100线/毫米的不锈钢基底原刻光栅调谐紫外预电离TEACO_2激光器,可以在80根谱线中选择振荡。输出光斑约4厘米×4厘米,光束角2毫弧度,通过二面凹凸镜R_1和R_2(10米曲率半径)注入CF_4管。CF_4管有效通光孔φ16毫米,两端用NaCl布氏角密封。HR_(1,2,3)为半反射镜,DR为双色片,对CO_2激光透过率为90％,对16微米反射率约85％。D_1、D_2、D_3分别为激光能量计和微能量计,前者可测焦耳级光能,后者可测微焦耳级光能。SP_1和SP_2分别为CO_2谱线分析仪和80线/毫米、定向16微米的0.5米平面光栅单色仪。LiF晶片用作选择性反射16微米的分光片。     

The identification of candidate transitions for optically pumped far infrared lasers: Methyl halides and D2O

Two hundred and forty-four candidate transitions for optically pumped far infrared lasers have been identified in C¹²H3F, C¹³H3F, C¹²D3F, C¹²H3Cl³⁵, C¹²H3Cl³⁷, C¹²H3Br⁷⁹, C¹²H3Br⁸¹, and D2O using as candidate pump lines, 781 in number, the isotopic forms of CO2, the sequence and hot bands of C¹²O2¹⁶, and the N2O bands. The dominant transition parameters responsible for strong emission from TEA, CW, and long pulse modes of operation were identified by a correlation between known experimental behavior and the pertinent transition parameters, the results being that strong TEA laser emission correlates with ground state population while strong CW and long pulse emission correlate with absorption coefficient. The candidate transitions were subsequently selected on the basis of these parameters using calculated transitions and assignments based on band data from high resolution laser-Stark spectroscopy and measured candidate pump frequencies.     

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.     

Optically pumped CW submillimeter emission lines from methyl mercaptan CH3SH

Twenty-three new emission lines of CH3SH have been observed and their polarization with respect to the pumping radiation determined, but no assignments have yet been made.     

Optically pumped NH3 as a high-gain amplifier forCO2 laser radiation

Optically pumped high-pressure mixtures of NH₃ in N₂ are shown to be efficient broadband amplifiers of pulsed CO₂ radiation. In a dilute NH₃ mixture at 6 atm a single-pass gain of 150 (21.8 dB) was measured for the 10P(34) CO₂ transition. Gain was observed in NH₃ at pressures as high as 10 atm. Experimental measurements were made for a range of wavelengths in the 10.7 μm region, and the results compared with calculations based on a rate-equation model     

Additional CW far infrared laser lines from CO2laser pumped cis 1,2 C2H2F2

Six new CW far infrared laser lines are reported for the cis 1, 2 C2H2F2molecule optically pumped by a CO2laser. Of these, two have high conversion efficiencies in the 1-2 percent range.     

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.