Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Saturation effects in gas-phase degenerate four-wave mixing spectroscopy: nonperturbative calculations

Not Accessible

Your library or personal account may give you access

Abstract

Saturation effects in gas-phase degenerate four-wave mixing (DFWM) are investigated for conditions of interest for diagnostic applications in flames and plasmas. In particular, the case in which Doppler and collisional broadening are comparable, as is often the case for flame species such as NO and OH, is investigated. DFWM line shapes and signal intensities are calculated nonperturbatively and compared with high-resolution laser measurements. In the nonperturbative calculations the time-dependent density-matrix equations for a two-level system interacting with three laser fields are integrated directly on a grid of spatial locations along the phase-matching axis. The electric-field amplitude for the DFWM signal is determined by multiplying the time-varying, laser-induced polarization at each grid point by the appropriate phase factor and then by summing over all grid points. The calculations are in excellent agreement with measurements of DFWM line shapes and signal intensities for NO in a buffer gas of He over a wide range of He pressure. Under saturation conditions the pressure dependence of the DFWM signal is reduced greatly compared with the unsaturated case. The signal level is still dependent on the ratio of pure dephasing to quenching collisions, even for saturation conditions. From the standpoint of minimal dependence on collisional processes it appears that operation with pump-laser intensities approximately equal to the saturation intensity is optimal. The dependence of the DFWM line shape and signal intensity on the ratio of probe to pump-laser intensity is also investigated.

© 1993 Optical Society of America

Full Article  |  PDF Article
More Like This
Effect of Doppler broadening on quantitative concentration measurements with degenerate four-wave mixing spectroscopy

Thomas A. Reichardt and Robert P. Lucht
J. Opt. Soc. Am. B 13(6) 1107-1119 (1996)

Degenerate four-wave mixing spectroscopy with short-pulse lasers: theoretical analysis

Thomas A. Reichardt and Robert P. Lucht
J. Opt. Soc. Am. B 13(12) 2807-2817 (1996)

Experimental investigation of saturated degenerate four-wave mixing for quantitative concentration measurements

Thomas A. Reichardt, William C. Giancola, Christopher M. Shappert, and Robert P. Lucht
Appl. Opt. 38(33) 6951-6961 (1999)

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Figures (20)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Equations (24)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved