The refractive index of evaporated PbI2 films, in the red region of the visible spectrum, can be reduced up to 18% by exposure to 488 nm light at film temperatures of 150–180 °C. Absorption in the same region remains very small throughout the process, until a temperature-dependent exposure threshold is reached, then rises rapidly due to scattering by photolysis-produced Pb agglomerates. For exposures below this threshold, localized band-gap states and/or bounded-plasma effects in the small Pb agglomerates give rise to an absorption band at 520 < λ < 580 nm, which causes the large refractive-index change. The photolysis in the polycrystalline films is uniform through the film rather than concentrated near the free surface, as in single crystals.
© 1975 Optical Society of AmericaFull Article | PDF Article
U. Eicker and J. I. B. Wilson
J. Opt. Soc. Am. B 8(3) 614-617 (1991)
John S. Hartman
Appl. Opt. 20(23) 4062-4072 (1981)
Karl H. Guenther
Appl. Opt. 23(20) 3612-3632 (1984)