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     

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.     

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.     

SMMW laser emission and frequency measurements in doubly-deuterated methyl fluoride (CHD2F)

Submillimeter wave laser action is reported in CHD2F on 17 "parent" transitions plus three cascade lines. Accurate heterodyne frequency measurements are reported for nine lines. Useful output powers of greater than 1 mW were observed for several lines. The strongest line, which is at 384.3 μm, is particularly significant because of its potential as a local oscillator for the 385 μm D2O laser.     

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.     

Submillimeter laser action of CW optically pumped CD2Cl2, CH2DOH, and CHD2OH

More than 30 laser lines, several of them with an intensity in the order of mW have been obtained in the submillimeter wavelength range from 100 to 900 μm by optically pumping the deuterated molecules of dichloromethane (CD2Cl2) and methanol (CD2HOH, CH2DOH) with a step tunable CO2laser.     

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.     

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.     

Laser4F3/2→4I9/2and4F3/2→4I13/2transitions in KY(WO4)2:Nd3+

We report the observation of lasing at 0.9137 μm and 1.3545 μm in neodymium-doped KY(WO4)2at 77 K. Transition cross sections, fluorescent line width, and branching ratios are given.     

Near single-line operation of a free-burning CS2/O2/N2O flame laser with a nondispersive optical cavity

The CS2/O2/N2O flame laser has been operated for the first time under conditions in which the spectral output is nearly single line. This transition is theP_{10-9}(17) of CO at 5.4265 μm, the same transition which was observed to oscillate in single-line fashion by Hirose et al. in an electrically initiated CO chemical laser. It is suggested that the unique behavior of this line may be due to its close proximity to aPbranch transition in an adjacent band, namely theP_{9-8}(23) line, such that the gain profiles of the two lines overlap. Calculations suggest that at the conditions of these experiments, the separation of the line centers for this pair is about 0.3 Å or less. TheP_{10-9}(17) transition was also found to be totally absent under certain conditions of high multiline power, particulary at low O2and N2O flows. This may be due to absorption by a high-bandRbranch transition at 5.4266 μm, namely theR_{15-16}(32) line.     

Beat-frequency between measurements between C12O216and C12O218lasers

Several beat frequencies in the range below 6 GHz have been measured using a C¹²O2¹⁶laser and a C¹²O2¹⁸laser operating on several pairs of closely spaced lines in the 9.3-μm region.     

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.     

Electronic- and phonon-terminated laser emission from Ho3+in BaY2F8

Infrared spontaneous and stimulated emission from Ho³⁺in BaY2F8is reported. In addition to the familiar⁵I_{7} rightarrow⁵I8transition at 2 μ,⁵F_{5} rightarrow⁵I5emission at 2.4μ and⁵I_{6} rightarrow⁵I7emission at 2.9μ are discussed. There are several unusual features of the 2-μ laser emission. At room temperature, phonon-terminated laser emission is observed at 2.171 μ. At 77 K a complex CW laser output is observed in a wavelength interval lying on the shoulder of a fluorescence line. The complex output is attributed to oscillation in transverse modes of the resonator. Oscillation is not observed in the strongest emission line, despite a large terminal state splitting of 310 cm^-1. These results are explained on the basis of a theory developed earlier for transition metal ion lasers. The validity of the model is supported by demonstrating the tunability through loss modulation predicted by theory. The observation of these effects is made possible by the very low internal scattering loss in the crystals. The⁵F_{5} rightarrow⁵I5laser lines near 2.4 μ represent relatively low gain transitions with pulse durations limited by accumulation in a longer lived terminal state. The dynamics of laser emission indicate the possible absence of thermal equilibrium in the excited state. For the 2.9-μ transition the bottleneck posed by a longer lived terminal state may be eliminated by the addition of Eu³⁺or Pr³⁺, but laser emission could not be obtained.     

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.     

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.     

Optically pumped FIR laser action in chlorofluoromethane (CH2CIF)

Thirteen new submillimeter laser lines have been detected in chlorofluoromethane optically pumped with a CW¹²C¹⁶O2laser. Their wavelengths measured in a Fabry-Perot resonator to an accuracy better than 0.5 percent, lie between 175 and 1014 μm.     

Transmission-loss characteristics of Al2O3-doped silica fibers

Transmission-loss characteristics of Al2O3-doped silica fibers have been investigated to develop an Al2O3alternative dopant for VAD silica-based optical fibers. Optical properties of Al2O3-doped silica bulk glass and fibers were measured in the0.11-30-mum spectral region. From the experimental results, the intrinsic loss due to glass material was estimated for Al2O3-doped silica fibers. The calculated intrinsic loss minima for Al2O3-doped silica fibers with 0.2- and 1.0- percent relative refractive-index differences were 0.17 dB/km at 1.548 μm and 0.28 dB/km at 1.565 μm, respectively.     

8B9--Laser emission at 1.06 µ from Nd3+-Yb3+glass

Laser emission at 1.015 μm occurs in glass singly doped and when sensitized with Nd³⁺. For double doping in a Li Mg Al Si glass, emission at 1.015 μm from Yb³⁺and 1.06 μm from Nd³⁺was reported. By monitoring the 1.35 μm fluorescent line of Nd³⁺, it can be shown that both Nd³⁺and Yb³⁺lase at 1.06 μm at room temperature in a silicate glass with 5 weight percent Nd2O3and 5 weight percent Yb2O3. Energy transfer from Nd³⁺to Yb³⁺is a linear function of the Yb³⁺concentration. The transfer increases with Nd³⁺concentration by about a factor of three in going from 1 weight percent Nd2O3to 6 weight percent Nd2O3and thereafter remains approximately constant. This indicates that the transfer from Nd³⁺to Yb³⁺is assisted by intermediate transfer steps between Nd³⁺ions. Additional transfer above 6 weight percent Nd2O3is prevented by concentration quenching.     

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.     

Theoretical and experimental studies of a multiline TEA CO2laser with hot CO2as an intracavity absorber

The multiline behavior of a ballast resistance helical TEA CO2laser incorporating hot CO2as an intracavity absorber has been studied. Simultaneous laser oscillation onP(16), P(18), andP(20)lines of 10.6 μm has been obtained reliably. A rate equation model has been developed for the hot CO2absorber and is incorporated with the model for the multiline TEA CO2laser for calculating laser intensities onP(16), P(18), P(20), andP(22)lines of the 10.6 μm band in the presence of the absorber. The theoretical calculations agree quite well with the experimental observations. These studies show that a hot CO2column of Proper length and temperature inside a TEA CO2laser cavity can produce simultaneous laser oscillation on at least three rotational linesP(16), P(18), andP(20)of the 10.6 μm band with almost equal intensity.