Concentration and medium dependencies in optical limiting of organic dyes

Abstract

A series of organic dyes in solutions of different concentrations were measured systematically for optical limiting responses toward collimated nanosecond pulsed laser light at 532 nm. The results show that for most of the dyes the optical limiting is solution concentration dependent when measured in optical cuvettes of different path lengths to maintain the same linear transmittance at the laser wavelength. A more concentrated solution in a cuvette of a shorter optical path length has a better optical limiting performance. The optical limiting responses of the dyes in a solid state matrix are significantly weaker than those in the concentrated solution (thus of a comparable optical path length) but similar to those in a very dilute solution. The metallophthalocyanines are noticeable exceptions, exhibiting optical limiting properties that are neither solution concentration dependent nor medium dependent. The results are discussed in terms of the reverse saturable absorption model and a recent modification already available in the literature. In addition, the consistent correlation between the two dependencies in the optical limiting of the same dye may allow the measurement at different solution concentrations to serve as a convenient experimental tool to screen candidate limiters for solid-state devices.