Measurement of refractive-index change at a liquid-solid interface close to the critical angle.
We measured the refractive-index change on a liquid sample, using the reflection of a polarized Gaussian laser beam close to the angle of total reflection. We applied this technique to a solution of nickel (ii) phthalocyanine tetrasulfonated (NiPTS) in water-ethanol (1/1 v/v), in which the nonlinearity of the refractive index is due to optically induced thermal effects. We show that close to the angle of total reflection the sensitivity of this technique is four times bigger than at normal incidence.
Martinelli
M
M
Laboratório de Optica Quântica, Instituto de Física da Universidade de São Paulo, PO Box 66318, São Paulo 05389-970, Brazil. mmartine@usp.br
Gugliotti
M
M
Horowicz
R J
RJ