Multiphoton contributions to far infrared generation in optically pumped deuterium oxide

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1979

OSTI ID:6212200

Petuchowski, S J

Far Infrared (FIR) emission at 66 and 50 ..mu..m in D/sub 2/O vapor, optically pumped with a CO/sub 2/ TEA laser, is shown to constitute a stimulated Raman process associated with each wave within a system of four molecular vibrational-rotational levels. A propagation model, based on a semiclassical, quasistatic (t much greater than T/sub 2/), density matrix analysis, is constructed and applied to the system. The model is generalized to include one-, two-, and three-wave interactions among three near-reasonant waves of arbitrary intensity in a variety of four-level system configurations. Level degeneracies and relative field polarizations are treated explicitly. New insignts are obtained regarding the AC Stark shifted gain spectra of each wave in the presence of the others. Parameters for the model are derived from calculations and measurements, the latter including a survey of infrared self pressure broadening coefficients in D/sub 2/O and an analysis of FIR self-absorption. A detailed characterization of the FIR evolution in a single-pass amplifier configuration reveals distinct threshold and saturation features as well as pump absorption behavior indicative of its nonlinear conversion of FIR radiation. Measurements of the FIR absorption in D/sub 2/O establishes that the emitted wavelengths are detuned by a degree commensurate with the measured pump detuning, again substantiating a stimulated Raman process. Agreement between the model calculations and the empirical data is shown with respect both to FIR temporal behavior and to 66 ..mu..m pulse energy vs D/sub 2/O pressure and pump intensity. Explicit account is taken of inhomogeneous broadening of the pump transition at lower D/sub 2/O pressures.

• Research Organization: Illinois Univ., Urbana (USA)
• OSTI ID: 6212200
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
CARBON DIOXIDE LASERS
ELECTROMAGNETIC RADIATION
EMISSION
ENERGY ABSORPTION
ENERGY-LEVEL TRANSITIONS
FAR INFRARED RADIATION
FLUIDS
GAS LASERS
GASES
HEAVY WATER
HYDROGEN COMPOUNDS
INFRARED RADIATION
LASERS
MATHEMATICAL MODELS
OPTICAL PUMPING
OXYGEN COMPOUNDS
PUMPING
RADIATIONS
RAMAN EFFECT
STARK EFFECT
STIMULATED EMISSION
VAPORS
WATER
WATER VAPOR