We report results of a systematic study examining the relationship of bond
type and concentration to the linear and non-linear optical properties of A
s-S-Se glasses. The effects of iso-structural substitution of Se for S and
the resulting impact on structure and the non-linear refractive index, n(2)
, are discussed. Non-linear optical properties of As-S-Se chalcogenide glas
ses were measured by the Z-scan technique at 1.6 mu m, and measured n(2) up
to 400 times the n(2) for silica were observed. Such large n(2) for glasse
s with small As/(S + Se) molar ratios is correlated with the presence of co
valent, homopolar Se-Se bonds in the glass structure as identified by Raman
spectroscopy, and can not be attributed to any red shift in the absorption
edge or to a resonant effect. The suitability of these glasses for planar
waveguides based on such nonlinear properties is thus confirmed, and recent
fabrication results are described. (C) 1999 Published by Elsevier Science
B.V. All rights reserved.