Accession Number:

ADA230183

Title:

Degenerate Four-Wave Mixing of CW HF Laser Beams in HF Absorption Cell

Descriptive Note:

Technical rept.

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS

Report Date:

1990-08-06

Pagination or Media Count:

48.0

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 P18, P19,or P110 transitions, provided total forward plus backward pump beam intensities of 130, 600, and 400 Wsq. cm., respectively, in the HF absorption cell. A probe beam intensity of the order of 10 Wsq. 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.

Subject Categories:

  • Lasers and Masers
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE