Accession Number : ADP006705
Title : Beam Fanning in Coupled-Wave Theory of 2-Beam Coupling,
Corporate Author : ROCKWELL INTERNATIONAL THOUSAND OAKS CA
Personal Author(s) : Ewbank, M. D. ; Vachss, F. R. ; Vazquez, R. A
Report Date : 22 MAY 1992
Pagination or Media Count : 4
Abstract : Simple coupled-wave theory accounts for depletion of the pump beam due to energy transfer (i.e., amplification) to the probe beam. Ignoring absorption, the probe gain g can be expressed as g = I sub 1(z) divided by I sub 1(O) = 1+r sub pp divided by 1+r sub pp e to the -Gamma z where I sub 1(O) is the incident probe intensity, Gamma is the two-beam-coupling coefficient and r sub pp is the incident pump-to-probe beam ratio given by r sub pp = I sub 2(O) divided by I sub 1(O) with I sub 2(O) being the incident pump intensity. Equation (1) remains valid even when the pump-to-probe ratio r sub pp is not sufficiently large (only the approximation for the probe gain g approximates e to the gamma L becomes invalid when r sub pp is not much greater than e to the gamma l). Similarly, the pump depletion d can be expressed as d = I sub 2(z) divided by I sub 2sO) = 1+r sub pp divided by r sub pp + e to the gamma z. These expressions for the probe gain and pump depletion have proven inadequate in describing the two-beam-coupling process, particularly when the coupling coefficient IF is very large (recently, r's exceeding 60/cm have been reported.
Descriptors : *OPTICAL PUMPING, ABSORPTION, COUPLINGS, DEPLETION, ENERGY, EQUATIONS, GAIN, INTENSITY, PROBES, PUMPS, RATIOS, THEORY, REFRACTION, SYMPOSIA.
Subject Categories : Optics
Distribution Statement : APPROVED FOR PUBLIC RELEASE