Degenerate Four-Wave Mixing of CW HF Laser Beams in HF Absorption Cell
Abstract
Phase conjugation of a cw hydrogen fluoride (HF) laser beam has been investigated experimentally and theoretically using resonant degenerate four- wave mixing (DFWM) in an HF gas absorption cell. A single-line single-mode HF laser, operating on P1(8), P1(9),or P1(10) transitions, provided total (forward plus backward) pump beam intensities of 130, 600, and 400 W/sq. cm., respectively, in the HF absorption cell. A probe beam intensity of the order of 10 W/sq. cm. was also provided. Conjugate reflection of the probe beam was investigated as a function of gas cell pressure and as a function of frequency detuning from line center. The variation of reflectivity with gas cell pressure at fixed laser beam intensity indicated a peak reflectivity of the order of . 0001 at pressures from 2 to 4 Torr. Measurement of conjugate beam intensity, as a function of frequency detuning from the line center,provided a signal with a full width at half maximum (FWHM) of about 30 MHz. The latter is of the order of the homogeneous width, for HF at the test pressure, and may be compared to the Doppler width delta nu sub d = 300 MHz for the medium. An Analytical model is presented which provides theoretical estimates for the variation of reflectivity with pressure. Effects of diffusion, thermal conduction, pump depletion, and a nonuniform (Gaussian) profile are considered. Theoretical estimates for peak reflectivity agree with experiments to within a factor of about 2.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 06, 1990
- Accession Number
- ADA230183
Entities
People
- Harold Mirels
- Jay M. Bernard
- John G. Coffer
- Richard A. Chodzko
Organizations
- The Aerospace Corporation