Passive optical limiting of picosecond-nanosecond laser pulses using highly nonlinear organic liquid cored fiber array

Abstract

We present a detailed account of theoretical and experimental studies of nonlinear molecular photonic processes accompanying the propagation of short intense laser pulses through an organic liquid cored fiber array. The theory takes into account two-photon absorption, excited state absorption, and dynamical evolution of the molecular energy level populations and the laser intensity. The coupled dynamical equations for the molecular energy-level populations and laser intensity are solved numerically using experimentally observed molecular and optical parameters. Experimentally obtained optical limiting results are analyzed along with nonlinear absorption and pump-probe studies of other nonlinear optical processes occurring in the fiber core. It is found that in the nanosecond time regime, besides excited state and two-photon absorption, thermal and density effects also contribute significantly to the optical limiting performance of the constituent fiber.