A common experimental problem with rotational coherent anti-Stokes Raman spectroscopy (CARS) is undesired spectral interference that is due to stray light from the primary laser beams. Also, for the most developed approach, dual-broadband rotational CARS, practical measurements often suffer from stray light interference from the narrow-band laser, inasmuch as the CARS signal is produced inherently in the spectral vicinity of the narrow-band laser beam. An optical filter does not provide a sufficiently sharp transmission profile, thus leading to signal loss and spectral distortion of the rotational CARS signal. An atomic filter consisting of a sodium-seeded flame is presented here as a solution to the problem, and its usefulness was demonstrated in dual-broadband rotational CARS experiments.
© 1998 Optical Society of America
(190.1900) Nonlinear optics : Diagnostic applications of nonlinear optics
(280.1740) Remote sensing and sensors : Combustion diagnostics
(300.6230) Spectroscopy : Spectroscopy, coherent anti-Stokes Raman scattering
(350.2450) Other areas of optics : Filters, absorption
Joakim Bood, Per-Erik Bengtsson, and Marcus Aldén, "Stray Light Rejection in Rotational Coherent Anti-Stokes Raman Spectroscopy by use of a Sodium-Seeded Flame," Appl. Opt. 37, 8392-8396 (1998)