Beam Fanning in Coupled-Wave Theory of 2-Beam Coupling

Abstract

Simple coupled-wave theory1,2 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 as1 where I1(0) is the incident probe intensity, Γ is the two-beam-coupling coefficient and rpp is the incident pump-to-probe beam ratio given by (2) with I2(0) being the incident pump intensity.