Theoretical investigation of the forward phase-matched geometry for degenerate four-wave mixing spectroscopy

Journal Article · Thu Oct 01 04:00:00 EDT 1998 · Journal of the Optical Society of America, Part B: Optical Physics

DOI:https://doi.org/10.1364/JOSAB.15.002566· OSTI ID:662202

Reichardt, T A; Lucht, R P ^[1]; Danehy, P M ^[2]; Farrow, R L ^[3]

---

1. Laser Diagnostics Laboratory, Department of Mechanical and Industrial Engineering, University of Illinois, 1206 W. Green Street, Urbana, Illinois 61801 (United States)
2. Department of Physics, The Faculties, The Australian National University, Canberra, ACT 0200 (Australia)
3. Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969 (United States)

We examine theoretically the degenerate four-wave mixing (DFWM) signal intensities and line shapes obtained with the forward phase-matched geometry in which all beams propagate in the same direction and compare the results to those of the phase-conjugate geometry with counterpropagating pump beams. To examine the forward phase-matched geometry, we modify a theoretical approach used previously to calculate phase-conjugate DFWM signal intensities. This theoretical approach, which involves numerical integration of the time-dependent density-matrix equations, is validated for the forward phase-matched geometry by comparison of our calculated line shapes to both a perturbative solution and to experimental data. This methodology is then used to compare the signal intensities and line shapes obtained with the forward phase-matched geometry and the phase-conjugate geometry in the perturbative (low laser power) and saturated (high laser power) regimes. In the perturbative regime the forward phase-matched signal exhibits less sensitivity to the Doppler linewidth. At pump laser intensities approximately equal to the saturation intensity the signal for the forward phase-matched geometry is stronger than that for the phase-conjugate geometry for primarily Doppler-broadened resonances, assuming the same probe volume for both geometries. These advantages warrant further investigations employing the forward phase-matched configuration for DFWM measurements of gas-phase species. {copyright} 1998 Optical Society of America

• OSTI ID: 662202
• Journal Information: Journal of the Optical Society of America, Part B: Optical Physics, Journal Name: Journal of the Optical Society of America, Part B: Optical Physics Journal Issue: 10 Vol. 15; ISSN JOBPDE; ISSN 0740-3224
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DOPPLER BROADENING
DOPPLER EFFECT
FREQUENCY MIXING
LINE WIDTHS
NONLINEAR OPTICS
SPECTROSCOPY
TIME RESOLUTION