Dual focal plane visible optical limiter

Experiments measuring the transmission of 5 nanosecond (FWHM), 532 nm pulse s through an optical limiter using two different nonlinear materials at two separate focal planes show by far the highest dynamic-range measured to da te. This cascaded focus, f/5 optical limiter combines self focusing and con sequent nonlinear scattering in CS2, with reverse saturable absorption in l ead-phthalocyanine (PbPc). Both the AC: Kerr effect and electrostriction co ntribute to the total refractive index change in CS2. Our beam propagation code is used to model the propagation of light through the 2 cm thick CS2 c ell placed at the first focus, which protects a second 0.1 mm cell containi ng a solution of PbPc placed at the second focus. An aperture is placed in the focal plane of a final focusing lens to measure the "encircled" energy defined as the energy passing through a 1.5 mrad diameter focal-plane apert ure. Experiments and modeling show that the strong self-focusing in the CS2 keeps the energy at the second cell below its damage threshold. This combi nation of nonlinearities clamps the maximum encircled energy below 1 muJ fo r input energies up to 14.5 mJ at a 10 Hz repetition rate. This corresponds to a dynamic range of at least 7500 while it is possibly much greater sinc e no damage occurred to any device components. Here we present details of t he operation of this device.