A. Vass

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.

Investigation into simultaneous fir laser emissions in CH2F2 using a homodyne detection system

Simultaneous FIR laser emissions in CH2F2 have been investigated using a Homodyne Transmit and Receive System. A new FIR cascade line at 196. 1um has been observed and assigned. The investigation has shown that the normal techniques for determining FIR laser efficiencies may not be completely adequate.

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.

Power broadening and nonlinear FIR magneto-photoconductivity in n-GaAs

The saturation of the photoconductivity due to 1s-2p+ shallow donor transitions in n-GaAs has been investigated using a high power cw-FIR-laser. Magnetic field strengths were chosen in such a way that 2p+ energy levels were either below or above the N=0 conduction band Landau level. In the former case 1s-p+ transitions are found to be inhomogeneously broadened with a saturation intensity as low as 0.84 mW/cm2, giving an effective lifetime of the 2p+ state of 1.5 μs. Above the band edge the integrated photoconductivity does not saturate though the intensity-normalized peak photosignal decreases and the linewidth increases with raising intensity. This strange behaviour is tentatively attributed to optical excitations of 2p+ electrons to higher lying electron Landau states.

A Submillimeter Homodyne Transmit and Receive System (HTRS) for detecting weak signals from reflectors

A Submillimetre Homodyne Transmit and Receive System has been developed to operate in the 500–2000 GHz region. The system is based around an Optically Pumped Submillimetre laser system and an optical processing system. The system will be described along with our test results which show detectivities of better than −130dBm at 693GHz.

Two-Photon Light Shift in Optically Pumped FIR Lasers

We have made the first observation of a far-infrared two-photon light shift (2PLS). The 2PLS — an excess splitting of the gain peaks due to bidirectional pumping — is monitored by beating the output of two 15NH3 OPFIRL’s [1]. The effect is related to, but distinct from that observed by BIALAS, FIRTH and TOSCHEK [2], and is described by the three-level system model of FELDMAN and FELD [3].

A High Power, High Efficiency, Isotopically CO2 Optically Pumped, 15NH3 Far-Infrared (FIR) Laser System

We report the generation of 180mW of FIR power at i53μm (15NH3 pumped by the isotopic 13C16O2 u laser) from a commercially available laser system. The fine tuning characteristics of the FIR laser are also discussed.