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     

Observation of a large number of new laser lines from12CD3F gas optically pumped with a continuouslytunable high-pressure pulsed CO2 laser

An observation is reported of a large number of new laser lines from ¹²CD₃F gas optically pumped with a continuously tunable high-pressure pulsed CO₂ laser. Making use of the coincidence of the 10 μm P and R branches of CO₂ with the v₃ and v₆ vibrational-rotational absorption bands of ¹²CD₃F, 180 laser lines were found in the wavenumber range between 8 and 55 cm^-1, all of them yet unknown; these lines are studied for characteristic properties of laser action. All laser lines are assigned as pure rotational transitions in the vibrational excited or ground states     

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     

High vibrational temperatures in optically-pumped CO2

A pulsed 4.3-μm CO₂ laser was used to optically pump mixtures of CO₂ and He, and create transient gain at 9 and 10 μm. A conventional continuous-wave CO₂ laser operating on both regular and sequence bands measures this transient gain, and determined the ν₃ (asymmetric stretching)-mode vibrational temperature T₃. The measured values of T ₃ are generally much higher than those attained in discharge-excited CO₂. It is shown that a Treanor distribution must be used to describe the populations in the ν₃ -mode when dilute mixtures of CO₂ in He are optically pumped to ν₃-mode temperatures of 3000 to 4000 K. Under these conditions the sequence-band gain coefficients are almost equal to those on the regular bands. The collisional relaxation of energy from the ν₃ mode shows evidence of fast V-T relaxation at high values of T₃, followed by a slower relaxation rate characteristic of the 00⁰1 population lifetime     

Observation and characterization of new FIR laser lines from formicacid

We report the observation and characterization of seven new far-infrared (FIR) laser lines from H¹²COOH and H¹³COOH in the range 232.2 to 746.6 μm optically pumped by a wide-tunability waveguide CO₂ laser. Their absorption frequency is outside of the tuning range of a conventional CO₂ pump laser     

Laser action in hydrazine: observation and characterization of newlarge offset FIR laser lines

Using for the first time a waveguide CO₂ laser with a tunability of 300 MHz, in order to pump large offset infrared absorptions, we obtained 34 new far-infrared laser lines from the hydrazine molecule; their wavelengths range from 155.2 to 669.3 μm. All of the new lines and some other already known laser emissions are characterized in the wavelength, the polarization relative to that of the pumping CO₂ laser, the optimum pressure of operation, relative intensity, and the offset relative to the CO₂ center frequency     

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 FIR laser lines from fully deuterated dichloromethane:completion of perpendicular/parallel emission pairs

We report 16 new far-infrared (FIR) laser emissions of CD₂ Cl₂. These lines are obtained by optically pumping the active molecule by means of a large-tunability waveguide CO₂ laser. Our tunability of 290 MHz around each CO₂ laser emission allows for the excitation of large-offset absorption transitions of CD₂Cl₂, not reachable by conventional CO₂ Lasers. While the overwhelming majority of the known FIR laser emissions of CD₂Cl₂ are polarized parallel to the polarization of the pump CO₂ line, 13 of the 16 new lines reported in this paper are polarized perpendicularly to the corresponding CO₂ pump line. The presence of both perpendicular and parallel lines is extremely important for the assignment of laser transitions     

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     

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.     

Pulse CO2 laser drilling of green alumina ceramic

Ceramics are used as thermal conductors and electrical insulators in integrated circuit packaging. We have investigated TEA CO₂ laser drilling of green alumina ceramic sheets consisting predominantly of alumina with approximately 10% PVB (polyvinyl butyral) as the polymer binder. Experiments with 9.5 and 10.6 μm wavelengths show that the holes made with a 9.5 μm CO₂ laser beam, where a larger percentage of the total laser energy is deposited directly into the polymer binder, are smaller, more straight-sided and cleaner     

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     

Tunable UV generation to 0.185 μm inCsB3O5

CsB₃O₅ has been found to be phase matchable for SFG down to 0.185 μm by mixing the fifth harmonic of a Nd:YAG laser at 1.0642 μm and the output of a KTP parametric oscillator pumped by the second harmonic of the same Nd:YAG laser at 20.0°C. Improved Sellmeier's equations and nonlinear optical constant of this crystal are reported     

An EMQ-switched CO2 laser as a pump source for afar-infrared laser with a high peak power and a high repetitionrate

A modified current pulsed Q (EMQ)-switched CO₂ laser which is Q-switched by a mechanical beam chopper in combination with a pulsed discharge current is discussed. The laser produces a very stable output with a peak power greater than 1 kW at a repetition rate of 1000 p.p.s. for all transitions in the P and R branches of the CO₂ spectrum. A CH₃F laser pumped by the EMQ-switched laser produces 496 μm radiation in a 6.5 W peak, 100 ns pulses at 500 p.p.s. in the lowest loss EH₁₁ mode     

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     

Phasematching of infrared nonlinear laser devices using AgGaS2

Refractive indexes of AgGaS₂ are measured using a tunable CO₂ laser at 9-11 μm, Nd:YAG, and He-Ne laser lines and compared with previous values. The phasematching angles calculated for difference-frequency mixing, upconversion, and parametric oscillation are found to agree better with the experimental values     

Narrow gain spikes and frequency pulling in the midinfrared ammonialaser

The gain of a 12-μm NH₃ laser transition, optically pumped by CO₂ laser radiation, has been measured under well-characterized conditions. Good agreement is found between the measured gain and theoretical calculations based on a three-level density matrix formalism. The theory was also employed to explain the stable frequency behavior of the NH₃ laser     

Er3+-Yb3+ and Er3+ doped fiberlasers

Single-mode fiber lasers operating at ~1.57 μm are described. Output powers of >2 mW are reported for laser diode pumped operation. Direct comparison is made between fiber lasers using sensitized erbium (Er³⁺ and Yb³⁺) and erbium on its own. The performance of Er³⁺-Yb³⁺ fiber lasers is analyzed in more detail as a function of fiber length. Both CW and Q-switched operations are studied and the results obtained demonstrate that practical sources at 1.5 μm are available from diode pumped Er³⁺ -Yb³⁺ systems     

Tunable UV generation to 0.2325 μm in LiB3O5

LiB₃O₅ has been found to be phase matchable for sum-frequency generation down to 0.2325 μm at 20.0°C by mixing the Nd:YAG laser wavelength at 1.0642 μm with the second harmonic of a visible dye laser. Sellmeier's equations, which are highly accurate from 0.22 to 1.32 μm, are reported. It is demonstrated that a much shorter wavelength of 0.218 μm could be generated in this compound by mixing the fourth harmonic of a Nd:YAG laser with the idler of the KNbO₃ parametric oscillator tuned to 1.208 μm     

Tunable laser pumped 3 μm Ho:YAlO3 laser

The tuning characteristics of the ⁵I₆ -⁵I₇ transition in a Ho:YAlO₃ laser, intracavity pumped by a 1.079 μm Nd:YalO₃ laser, were studied. Operation on seven distinct lines between 2.844 and 3.017 μm was found, and the threshold and relative slope efficiency of each line was measured. Several of these lines were previously unreported