A STUDY OF THE NONLINEAR-OPTICAL TRANSMITTANCE IN A VARIETY OF TCNQ-BASED ORGANOMETALLIC COLLOIDAL SUSPENSIONS

Optical limiting in a series of novel aqueous colloidal suspensions is investigated. The suspensions consist of an organometallic charge-tra nsfer complex based on the organic acceptor 7,7,8,8-tetracyanoquinodim ethane (TCNQ). We report on the synthesis of the organometallic comple xes and their effectiveness at limiting nanosecond pulses at 532 nm. I t is shown that some of the charge-transfer systems can effectively at tenuate pulses at rates up to 10 Hz while other systems require contin uous agitation in order to most efficiently limit the laser radiation. Finally we discuss the reversible field-induced phase transition that produces the observed nonlinear absorption.