Quality of the Stokes beam in stimulated Raman scattering

• Published in: IEEE journal of quantum electronics 1994-09, Vol.30 (9), p.2211-2219
• Main Authors: van den Heuvel, J.C., van Putten, F.J.M., Lerou, R.J.L.
• Format: Article
• Language: English
• Subjects: 426002 - Engineering- Lasers & Masers- (1990-); BEAM PROFILES; Coherence; Diffraction; ELECTROMAGNETIC RADIATION; ENGINEERING; Exact sciences and technology; FREQUENCY CONVERTERS; Fundamental areas of phenomenology (including applications); Gaussian processes; GSM; Laser beams; Laser excitation; LASER RADIATION; LASERS; MATHEMATICS; NEODYMIUM LASERS; Nonlinear optics; NUMERICAL ANALYSIS; Optics; Phase distortion; Physics; Pump lasers; RADIATIONS; RAMAN EFFECT; Raman scattering; SOLID STATE LASERS; Stimulated emission; Stimulated raman scattering; cars; WAVELENGTHS
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/3.309885

Stokes beam quality as obtained by stimulated Raman scattering is investigated numerically using various pump-beam profiles. It is found that the quality of the Stokes beam, expressed by M/sup 2/, is often roughly the same as the pump beam. For pump beams with Gaussian-Hermite modes, TEM/sub 00/ and TEM/sub 01/, the Stokes beam has the same-phase relation and M/sup 2/ as the pump beam. However, the TEM/sub 11/ pump beam, which has an M/sup 2/ of 3.0, gives a Stokes beam with a higher M/sup 2/, namely 3.7, and a distorted phase relation. For a Gaussian-Schell model beam, the M/sup 2/ of the Stokes beam is equal to that of the pump if the Stokes has the same wavelength as the pump; if the ratio of the Stokes and the pump wavelength increases, then the M/sup 2/ of the Stokes beam decreases. Experimental verification was obtained using a pump beam with an M/sup 2/ of 8.7 and a wavelength of 1.06 /spl mu/m. The generated Stokes beam at 1.54 /spl mu/m had an M/sup 2/ of 5.8, which agrees well with the numerical M/sup 2/ of 6.1.< >