Leverson F. L. Costa

New far-infrared laser lines from CH/sub 3/OD methanol deuterated isotope

We report on a study of the CH/sub 3/OD molecule in a search for new far-infrared (FIR) laser lines. For optical pumping of large offset vibrational absorption transitions, a continuous-wave waveguide CO/sub 2/ laser with 300 MHz tunability around each line was used for the first time. As a consequence, 17 new far-infrared laser emissions were observed. For these lines, we also present data on wavelength, intensity, offset, relative polarization, and optimum operation pressure.

DCOOD Optically Pumped by a 13CO2 Laser: New Terahertz Laser Lines

In this work, we report new optically pumped terahertz laser lines from DCOOD. An isotopic 13CO2 laser was used for first time as pump source, and a Fabry–Perot open cavity was used as a terahertz laser resonator. Optoacoustic absorption spectra were used as a guide to search for new terahertz laser lines. We could observe six new laser lines in the range from 303.8 μm (0.987 THz) to 725.l μm (0.413 THz). 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 both for this laser lines.

Continuous and Pulsed THz generation with molecular gas lasers and photoconductive antennas gated by femtosecond pulses

TeraHertz waves, associated with the far-infrared region of the electromagnetic spectrum, are gaining increasing interest in the past years due to promising applications in imaging, spectroscopy, and even communications. Here we report THz generation based on two systems: 1) continuous-wave (cw) laser generation in molecular gas lasers, and 2) short pulse generation in photoconductive antennas, gated by femtosecond near-infrared Ti:sapphire lasers. With the first system, we have generated tens of monochromatic CW laser lines over the last years, extending roughly from 40 microns to several hundred microns. This is done by optical pumping of gas lasers based on polar molecules such as methanol and its isotopes. In the second system, under development, pulsed THz radiation is generated by a photoconductive antenna built in a semi-insulating GaAs substrate excited by femtosecond pulses from a near-infrared (800 nm) Ti:sapphire laser.

TeraHertz Laser Generation by Optically Pumped Polar Molecules

Twelve new optically pumped far-infrared (FIR) laser lines is reported from CH3OH and 19 from 13CH3OH. A 13CO2 laser was used as pump source, and a Fabry-Perot cavity was used as a FIR laser resonator.

FIR laser lines from CH3OD: A review

The methanol isotopic species CH3OD has also proved to be an efficient and powerful medium to generate radiation in the far infrared (FIR) region. After the critical review of 1994, six papers have been published dealing with new FIR laser lines from this molecule. As a consequence of the use of wide tunability waveguide CO2 lasers as well as a new pulsed CO2 laser operating at hot and sequential bands, as of optical pumping sources, the total number of the FIR laser lines increased from 122 in 1994 to 227 today. In this communication we present an updated and complete catalogue of FIR laser lines generated from CH3OD. Information on wavelength, offset, relative polarization, intensity, and optimum operation pressure is generally available.