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Isotropic Liquid Crystal Fiber Structures for Passive Optical Limiting of Short Laser Pulses

I. C. Khoo, Pennsylvania State University, University Park, Pa.

Ever since the invention of the laser, there has been a need to protect the eye or sensitive optical sensors from damage by overexposure. The problem has become increasingly difficult with the advent of frequency agile high power pulsed lasers, which negate fixed line filters or optoelectronics/mechanical devices; all-optical or nonlinear optical means have to be used. In this context, various device concepts and nonlinear optical materials are being investigated. To satisfy such stringent requirements, it has become necessary to optimize both the device function and the material responses by specialized optical configurations. One means of achieving this is to use fiber or waveguide geometry in which highly intensity dependent (optical limiting) processes occur more efficiently due to the spatial confinement over distances much longer than the Rayleigh range of tightly focused lasers.