Abstract

5-(2-methylthio-4-methyl-5-pyrimidinyl)2,4-pentadiyne-l-oltosylate (PDATS) is a novel organic semiconductor material that may have large optical nonlinearity because of its one-dimensional π-electron conjugation. The laser employed in the optical nonlinear measurements is a Q-switched Nd:YAG laser with a pulse width of 8 ns, a wavelength of 532 nm, and a repetition rate of 10 Hz. The sample of PDATS, chloroform, is contained in a glass cell with a path-length of 0.5 cm. Linear transmittances of sample are selected to be 90%, 56%, and 26%, respectively. Experimental limiting characteristics of PDATS in chloroform with different transmittances are shown in Fig. 1. The symbols A, O, and x denote optical-limiting characteristics with linear transmittances of 90%, 56%, and 26%, respectively. The curve of transmittance versus input fluence (T = 90%) is shown in Fig. 2. When the input fluence reaches 400 mJ/cm², the transmittance decreases to 45%. The limiting threshold is 400 mJ / cm², and the clamped output is 300 mJ/cm². The results show that this material has a good optical- limiting behavior at high linear transmittance. PDATS is a potential candidate for the first stage of a cascaded limiter.

© 1995 Optical Society of America