Effect On Beam Quality Of Lransient Refractive-Index Changes In Stimulated Raman Scattering

A. Flusberg; D. Korff

doi:10.1117/12.975491

25 November 1986 Effect On Beam Quality Of Lransient Refractive-Index Changes In Stimulated Raman Scattering

A. Flusberg, D. Korff

Proceedings Volume 0642, Modeling and Simulation of Optoelectronic Systems; (1986) https://doi.org/10.1117/12.975491
Event: 1986 Technical Symposium Southeast, 1986, Orlando, United States

Abstract

Two sources of phase aberrations during amplification by stimulated Raman scattering have been studied. Both are caused by intensity nonuniformity in the incident pump laser beam. First, nonuniform population transfer of molecules undergoing the Raman transition results in a cumulative refractivity nonuniformity associated with the difference between the polarizabilities of the two molecular states. As shown experimentally by Butylkin et al. and Baklushina et al., the fractional polarizability difference for the Q(l) vibrational transition of H₂ is ≈0.15-0.20. As a result, this effect becomes large at a fluence nonuniformity level >33/cm². The dependence on fluence, rather than intensity, arises from the cumulative population transfer that takes place when the relaxation of the upper level during the laser pulse only weakly affects the population difference. Second, collisional relaxation of the excited population during the pulse causes heating and a nonuniform density distribution; this effect becomes more important as the pulselength is increased or the spatial scale size of the intensity gradients is decreased. The equations coupling the pump and Stokes fields to the refractivity and density changes are solved in the ray-optics limit of collimated beams and the effect on beam quality is determined. It is shown that in the limit of weak refractivity effects and negligible heating the beam-quality loss varies as the square of the rms fluence modulation.

Citation Download Citation

A. Flusberg and D. Korff "Effect On Beam Quality Of Lransient Refractive-Index Changes In Stimulated Raman Scattering", Proc. SPIE 0642, Modeling and Simulation of Optoelectronic Systems, (25 November 1986); https://doi.org/10.1117/12.975491

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available