Factors which affect the design of passive optical power limiters utilizing nonlinear refraction and absorption are discussed. Recent theoretical modelling and experimental studies of the effects produced by varying the thickness and position of the nonlinear medium are reported. Excessive thickness can produce large insertion loss for the limiter in the event of linear absorption or scattering, and also makes retrofitting to existing equipment difficult. Insufficient thickness results in less than optimal limiting. We show that for a third-order refractive nonlinearity a suitable medium thickness is six times the Rayleigh length of the beam inside the medium. Nonlinear absorption can enhance the limiting, allowing for the use of larger apertures or no apertures, and hence greater fields of view. We also show how the optimal position of the medium depends upon the ratio of nonlinear refraction to nonlinear absorption.

Date Published: 6 July 1994
PDF: 12 pages
Proc. SPIE 2229, Nonlinear Optical Materials for Switching and Limiting, (6 July 1994); doi: 10.1117/12.179582

Published in SPIE Proceedings Vol. 2229:
Nonlinear Optical Materials for Switching and Limiting
M. J. Soileau, Editor(s)