A method has been developed for experimentally measuring the irradiance (energy per unit area) of optical radiation required to stimulate nonlinear processes. The method involves examining the spatial dependence of the process in the vicinity of a laser beam focus. A laser operating in the lowest order transverse mode is required. The treatment is exact for multiphoton processes in the absence of relaxation of recombination and is approximate for other nonlinear processes.
© 1978 Optical Society of America
V. E. Merchant, "Determination of optical irradiance in nonlinear processes," Appl. Opt. 17, 3604-3607 (1978)