C.R. Pidgeon

An optically pumped waveguide laser with mesh reflectors

Abstract An optically pumped far infrared waveguide laser has been operated using metallic meshes as laser reflectors. The radiation modes sustained in the waveguide laser have been examined, and the use of the laser for magneto-optical measurements demonstrated.

Stimulated spin-flip Raman scattering: a magnetically tunable infrared laser. I

A microscopic theory of spin-flip Raman scattering from conduction electrons in semiconductors has been set out both in terms of appropriate general scattering theory and of detailed calculation of the electron band states of a solid in a magnetic field. From the latter, matrix elements determining the scattering cross-section have been evaluated as a function of frequency and magnetic field for the various ‘anharmonic’ processes involved in indium antimonide. New experimental results on magnetic field dependence of gain and loss, of direct relevance to comparison with microscopic theory, are presented and discussed. These results, together with earlier work, confirm the basic theoretical model and clearly demonstrate the potential of this continuously tunable infrared laser.

New FIR laser lines from an optically pumped far-infrared laser with isotopic 13C16O2 pumping

Abstract A 13 C 16 O 2 laser optically pumping a FIR laser has resulted in 17 new FIR cw emissions from 78.5 μm to 917 μm. The FIR media were: CD 3 OD, CH 3 OD, CD 3 OH, NH 3 and 15 NH 3 . Interesting effects have been observed with a combination of NH 3 and CD 3 OD resulting in a new FIR emission. Two new FIR emissions at 181.5 μm and 355.5 μm have been observed with a 12 C 16 O 2 laser optically pumping CD 3 OD.

Relaxation oscillations in cw optically pumped CD3OD and15NH3 lasers

We report the results of heterodyne measurements of the mode quality and tuning range of a cw CO2 laser designed for optically pumping a far-infrared (FIR) molecular laser, and describe the implications of multi-mode operation. In particular we report the observation of relaxation oscillations in the output of a FIR waveguide laser.

Dispersion in a cw optically pumped FIR laser

Direct frequency measurements of a13CO2/15NH3 OPFIRL output show that laser pulling effects give shifts of a few MHz, which agree well with a density matrix calculation.

Mode properties of optically pumped infrared waveguide lasers

Abstract An optically pumped CF3OH far i.r. waveguide laser has been operated using metallic meshes as laser reflectors. The radiation modes sustained in metal and glass waveguides have been examined, and the use of the laser for magneto-optical measurements demonstrated.

Tunable far-infrared generation by difference frequency mixing in InSb

Abstract Far-infrared radiation tunable over the range 85–105 cm -1 and at power levels of up to 10 μW has been generated by difference frequency mixing in InSb. The infra-red radiations which are mixed are a 10.6 μm TEA-CO 2 laser line and the tunable Stokes radiation produced from it by spin-flip Raman-laser action, again in an InSb sample. It is argued that careful choice of the free-carrier concentrations in the crystals used for (a) the Stokes generation and (b) the mixing, or the application of an electric field across the mixing sample, should considerably improve the far-infrared power levels.

Operating characterics of an optically pumped waveguide fir laser

Abstract We report measurements of the effect of resonator length changes, 13 CO 2 laser frequency and 13 CO 2 laser intensity on the FIR power emitted by an optically pumped waveguide FIR laser operating on the exceptionally strong 15 NH 3 laser line at 152.9 μm. The Doppler-splitting of the FIR output frequency shows a CO 2 power-dependent deviation from the linear dependence on 13 CO 2 laser frequency expected from rate equation theory. Similar, but weaker, effects are also reported using the less strong CH 3 OH FIR line at 118.8 μm.

Experimental characteristics of a high-power ammonia laser

Optically pumped NH3 laser emission at 12.8 mu m with signal strengths approximately 775 kW and efficiencies of 10% are reported. The fine temporal structure of the emission is shown to be fast (<5 ns) and output powers are shown to scale with pressure and pump power.

High power pulsed operation of a tunable spin-flip raman laser at low magnetic field

Abstract We report high power (kW), high efficiency (40%) operation of a pulsed tunable spin-flip Raman laser near 5.3 μm, with magnetic fields as low as 0.9 kG. Continuous tuning over a range of 52 cm -1 with radiation linewidths of 2 X 10 -2 cm -1 has been obtained using a low field (7kG) electromagnet.