Optical pumping by CO2and N2O lasers: New CW FIR emissions in 1,1-difluoroethane

53 new CW FIR laser lines are reported in 1,1-difluoroethane optically pumped near 10 μm by CO2and N2O lasers. The emission spectrum initially reported in the literature consisted of four lines between 770 and 458 μm and has now been extended to the 2.39 mm- 319 μm region. The reason for this extension, especially to the long wavelengths, is analyzed.     

Observation of new FIR superradiant lines from optically pumped D2O

Four new laser lines from optically pumped D2O vapor are reported at wavelengths of 235 μm, 280 μm, 97 μm, and 98 μm, the latter having a quantum conversion efficiency of 38 percent.     

New frequency measurements and laser lines of optically pumped12CH3OH

The frequencies of 70 optically pumped CW FIR¹²CH3OH laser lines have been measured relative to stabilized CO2lasers. Fifteen new laser lines together with the relative output powers and polarizations for most of the 104 known lines pumped by laser lines in the normal 9 and 10 μm bands of¹²C¹⁶O2are also reported.     

Pressure dependence of the infrared laser lines in barium vapor

We have studied nine laser transitions in Ba vapor at wavelengths between 1.13 and 3.05 μm. Three of these laser lines have not been reported previously. The relative intensities of the four strongest transitions (1.13, 1.50, 2.55, and 2.92 μm) vary with buffer gas pressure, suggesting that collisional deexcitation of the 6p¹P1state occurs at higher pressure and is the main mechanism populating the upper states of the 2.55 and 2.33 μm lines.     

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.     

Far infrared frequency synthesis with stabilized CO2lasers: Accurate measurements of the water vapor and methyl alcohol laser frequencies

A far infrared (FIR) frequency synthesis technique using saturated-absorption stabilized CO2lasers and a point-contact diode has been used to measure frequencies of a number of strong CW H2O, D2O, and CH3OH laser lines. The first frequency measurements of the 79-μm H2O, the 73- and 108-μm D2O, and 11 CO2-pumped CW¹²CH2¹⁶OH laser lines are reported. This measurement is the first demonstration of the general usefulness of CO2lasers for accurate synthesis of FIR frequencies.     

Investigation of D2O-laser emission at 50, 66, 83, 111, and 116 µm

A D2O laser oscillator axially pumped by a TEA CO2laser operating on the9P(32)line has been investigated. The laser emits five FIR lines whose emission characteristics are presented. For the three strongest lines (66, 111, and 116 μm) and an oscillator of length 45 cm, a single axial mode can be made to dominate. Special attention is drawn to the newly discovered and identified 111 μm line.     

Observation and assignment of large offset farinfrared laser lines in CH3OH optically pumped by a CO2waveguide laser

Four new FIR laser lines at 62.98, 48.77, 224.53, and 190.65 μm are reported from CH3OH, optically pumped by the 10R34 and 9R10 lines of a waveguide CO2laser. Measurements performed by several techniques confirm that the pump offsets are outside the tuning range of conventional CO2lasers. Two of the lines are assigned as highJtransitions within the torsional ground state of the CO stretch.     

Observations of anomalous gain coefficients in TEA double-discharge CO2lasers

Direct measurements of the gain coefficient of a TEA double-discharge CO2laser versus wavelength show that while the overall wavelength dependence is in good agreement with that predicted from the model wherein the rotational levels are in thermal equilibrium,P(20)in the 10.4-μm band andP(22)in the 9.4-μm band have a gain coefficient that is ∼10-percent high. These results are interpreted as evidence for stimulated emission from "hot bands" by these laser lines. Other transitions in these two bands should also exhibit gain coefficients that have been enhanced to a lesser degree.     

Line competition in the neutral argon laser

Uncertainties in transition assignments for the neutral argon laser lines at 1.792 and 2.208 μm have been resolved by operation of a CW neutral argon laser with several simultaneous output wavelengths. The observed competition effects have established the correct transition for the 1.792-μm line to be3d(1/2)_{1}deg -4p(3/2)_{2}and for the 2.208-μm line to be3d(1/2)_{1}deg -4p'(3/2)_{2}.     

Submillimeter laser action of CW optically pumped CF3Br

Far infrared laser action at 823 and 883 μm is reported for the first time from the optically pumped CF3Br molecule. This molecule exhibits strong absorptions in thePandRbranches of the 9 μm band of the CW CO2laser. Tentative assignments are proposed for the first two transitions observed.     

Fluorescence and oscillation characteristics of LiNdP4O12lasers at 1.317 µm

Spectroscopic data and laser oscillation characteristics of the 1.317 μ line in lithium neodymium tetraphosphate (LNP) are reported. A stimulated emission cross section of this transition was spectroscopically determined as7.1 times 10^{-20}cm², which corresponds to 1/4.5 of that at the 1.047-μm transition. Cross-section temperature dependence, laser cavity loss, threshold versus crystal length, and threshold temperature dependence were measured experimentally. Since resonant loss was negligible at the 1.317 μm line, room temperature threshold is lower than that at 1.047-μm in the case of long crystal, and threshold temperature dependence is weaker than that at 1.047 μm. A miniaturized LNP laser, using a graded index fiber as a focusing medium, is also shown. LED pump intensity required to obtain a constant output is compared for 1.047- and 1.317-μm wavelengths. The 1.317-μm line seems to be useful as miniaturized optical sources in optical communication systems, since required intensity is around several W/cm²for the side pump, and the wavelength corresponds to the most transparent band of ultra low-loss optical fibers.     

New CW far-infrared laser lines from CO2laser-pumped CD3OH

Twenty-one new CW far-infrared laser lines have been observed from the CD3OH molecule pumped by a CO2laser. The wavelengths of these new lines fall in the short wavelength range from 34.5 to 287 μm.     

Millimeter and submillimeter-wave laser action in symmetric top molecules optically pumped via perpendicular absorption bands

Ninety-nine new far infrared (FIR) laser lines from 227 μm to 1.965 mm have been observed in CH3CN, CH3CCH, CH3Cl, CH3Br,and CH3I by optically pumping these gases with CO2-laser pulses of 150-μs duration.     

New far-infrared laser lines from CO2-laser-pumped CH3OH gas by using a copper waveguide cavity

Eleven new far-infrared (FIR) laser lines have been observed from CH3OH pumped by a CO2laser. These lines are ranged from 78 to 694 μm and are obtained by using a copper waveguide cavity.     

Broadband emission and laser action of Cr3+doped zinc tungstate at 1 µm wavelength

We report on the spectroscopic properties of Cr : ZnWO4, which channels all the fluorescence into the broadband⁴T2-⁴A2transition at about 1 μm wavelength. Two different Cr³⁺centers with lifetimes of 0.5 and 5.4 μs at 300 K are analyzed. Both centers emit broad-band fluorescence with zero-phonon lines located at 834 and 877 nm wavelength. The effect of intrinsic and extrinsic charge compensation on the Cr³⁺centers is explained by a local and nonlocal compensation mechanism. With intrinsically compensated crystals we obtained CW laser action at 77 K and pulsed laser action at 300 K.     

New laser lines with wavelengths from λ = 61.7 µm down to λ = 27.7 µm in optically pumped CH3OH and CD3OH

25 new CW far infrared laser lines have been observed with wavelengths fromlambda = 61.7 mum down tolambda = 27.7 mum. We have significantly increased the number of known short wavelength laser lines and extended the laser line spectrum to the 30 μm region by using a BaF2outcoupling system.     

Far infrared laser emission from15NH3optically pumped by a CW sequence band CO2laser

Two new coincidences between theP(31) andP(35) CO210.6 μm sequence band emission lines and the¹⁵NH3absorption lines have been found to produce far infrared (FIR) emission lines atlambda = 111.9and 218 μm. In addition, the known coincidence between the regularR(42) 10.6 μm band CO2emission line and theasR     

CO(v = 2:1) laser transitions from He-air-CH4

A flowing electrochemically excited liquid-nitrogen-cooled He-air-CH4-(CO) laser was operated inQ-switched fashion yielding 20 CO laser lines below 5.0 μ. These laser lines were measured to occur from 4.7848 to 4.9880 μ. The lines were all identified to result fromP(J)_{upsilon,upsilon'}CO vibrational-rotational transitions as low asupsilon = 2:1. Nine suchupsilon = 2:1transitions were measured.     

Stark cell noise reduction of a CO2laser beam

A technique is demonstrated for reducing the rapid intensity fluctuations in the beam of a single frequency, polarized CO2laser tuned to theP(20)transition at 10.6 μm. The method uses a Stark-tunable absorption line in NH2D to compensate for the fluctuations of the laser output. Substantial reductions in laser beam intensity noise have been obtained. The method may be applied to other lines of the CO2laser and indeed to other types of lasers.