Molecular photonics of a highly nonlinear organic fiber core liquid for picosecond–nanosecond optical limiting application

Abstract

Recently obtained results of optical limiting studies with picosecond and nanosecond laser pulses in a nonlinear organic fiber core liquid L34 are analyzed with a model that accounts for linear, two-photon, intermediate, and excited-state absorptions. Explicit expressions for the laser induced molecular level density changes, and the nonlinear transmission and optical limiting of picosecond laser pulses are obtained. These theoretical considerations and experimental results enable us to characterize the limiting effectiveness of L34 and several nonlinear fiber core liquids. In particular, the roles played by two-photon, intermediate and excited-state absorptions of picosecond and nanosecond laser pulse pulses through ILC cored fibers and bulk films are thoroughly examined. In the nanosecond time scale, significant contributions from thermal/density effects are detected. Together with new insights into the complex intensity-dependent nonlinear transmission in the liquid fiber cores, we have also demonstrated the feasibility of using such fiber arrays for limiting picosecond and nanosecond laser pulses to below the eye/sensor damage level.