Author_Institution :
Liquid Crystal Inst., Kent State Univ., OH, USA
Abstract :
Summary form only given. It is very important to create photonic devices (e.g., optical power limiters, switches) for green, Nd:YAG pulsed laser radiation. Previously, it was shown that 25-100-/spl mu/m path-length liquid-crystal (LC) layers may have, for nanosecond, 532-nm irradiation, extraordinarily high values of nonlinear absorption coefficient /spl beta/, and refractive coefficient n/sub 2/ even in the transient regime, which is of considerable practical interest. Two competing mechanisms drive the value of n/sub 2/ in LC media in the nanosecond regime: (1) the orientational nonlinearity (with relaxation time of the order of tens to hundreds of nanoseconds) and (2) thermal and density ones. Which of the mechanisms dominates, depends on the preparation of the LC layer, laser pulse duration, /spl beta/, and the incident-beam spot size. For this reason the work aims at understanding how preparation of LC layers influence this nonlinear response.
Keywords :
absorption coefficients; dichroism; liquid crystals; liquid films; molecular orientation; nematic liquid crystals; nonlinear optics; optical films; optical materials; refractive index; two-photon processes; 2 to 10 Hz; 25 to 100 mum; 532 nm; Nd:YAG pulsed laser radiation; YAG:Nd; YAl5O12:Nd; competing mechanisms; density nonlinearity; green; incident-beam spot size; laser pulse duration; linearly polarized nanosecond laser radiation; liquid crystals; liquid-crystal layers; nanosecond regime; nonlinear absorption; nonlinear absorption coefficient; nonlinear refraction; nonlinear response; optical power limiters; orientational nonlinearity; photonic devices; refractive coefficient; relaxation time; switches; thermal nonlinearity; transient regime; Absorption; Apertures; Chemical lasers; Laser modes; Liquid crystal devices; Liquid crystals; Optical devices; Optical refraction; Photonic crystals; Polarization;
