A new pulsed CO₂laser yielding new FIR laser lines from CH₃OD pumped by the 10P and 10HP lines

Abstract

Using a novel CO 2 pulsed laser that presents high peak power (several hundreds of watts) together with high spectral purity, we have reinvestigated the CH 3 OD isotopomer of methanol as a source of far infrared laser emissions pumped by the 10P and 10HP CO 2 laser lines. Thirty-five new lines have been observed and characterized for wavelength, offset, relative polarization, optimum operation pressure and relative intensity.

IR and FIR Spectroscopy of 13CH3I

“…The emission lines are selected by means of a diffraction grating of 150 lines/mm, while the fine laser frequency tuning is performed by a piezoelectric transducer (PZT) supporting the ZnSe output mirror. The laser operates in a pulse regime with the discharge splitted into two symmetric branches with two central anodes and two cathodes, in order to avoid too large voltages near the laser frame; each discharge is driven by a home made solid state power supply based on the discharge of two capacitors driven by Toshiba IGBT transistors [4,5]. The two capacitors are charged to about 1 kV, then the peak voltage is enhanced by means of a step-up transformer to the 20-30 kV needed for the laser operation.…”

“…The working conditions to operate in the 10HP band are quite different from those of the regular bands: the optimum gas pressures for the 10HP band are 1.9 kPa of CO 2 , 1.3 kPa of N 2 and 2.1 kPa of He and also the charging voltage on the capacitors of the power supply must be adjusted for this band. A detailed description of our pump laser and its best working conditions for each emission band can be found in De Michele et al [5].…”

“…We have re-investigated the 13 CH 3 I molecule with our new pulsed waveguided CO 2 pump laser [4,5]. We have discovered two new FIR laser emissions and we give further spectroscopic information about polarization and pump frequency offset for five already known lines.…”

Infrared and far-infrared spectroscopy of 13CH3OH: TeraHertz laser lines and assignments

“…The accidental coincidence between CO 2 laser lines and a molecular absorption is the rather stringent condition for THz laser emission. To minimize this limitation, several auxiliary techniques were used to increase the possibility of accidental coincidences which can potentially lead to new laser emissions: the use of waveguide CO 2 laser of wide tunability [6], of acoustooptic modulators and hybrid metal-dielectric waveguide cavity [7], the use of hot and sequential CO 2 laser lines [8] and the use of isotopic CO 2 lasers [9,10]. The renewed interest on powerful sources of electromagnetic radiation in the TeraHertz region for use in imaging and medicine [11,12] is a strong motivation to reinvestigate the 13 CH 3 OH molecule using now for the first time a 13 CO 2 laser as optical pump source.…”