Measurement of the induced refractive index in a photothermorefractive glass by a liquid-cell shearing interferometer

Abstract

A liquid-cell shearing interferometer was developed to measure refractive-index variations (delta n) in transparent materials. The cell was filled with a liquid having a matched refractive index. The achieved resolution was better than 1/1000 of a fringe shift and resulted in a delta n measurement sensitivity down to 10(-7) for 1-mm-thick samples. A refractive-index increment in photothermorefractive glass of up to 5 x 10(-6) was observed after UV exposure at 325 nm. A refractive-index decrement of up to 1 x 10(-3) was observed after thermal development of the exposed sample. It was proved that photothermorefractive glass obeys the reciprocity law; i.e., delta n depends on the UV dosage but does not depend on the irradiance.

Nonlinear photosensitivity of photo-thermo-refractive glass by high intensity laser irradiation

“…At wavelengths longer than 350 nm cerium ions are no longer absorbing and therefore PTR glass shows no linear photosensitivity. Photosensitivity characterization of PTR glass for CW laser exposure has been reported previously [9]. The classical method consists in determining the evolution of induced refractive index change Dn (in ppm) vs. exposing energy dosage D (J/cm 2 ) at constant intensity.…”

“…Samples of PTR glasses of composition 15Na 2 O-5ZnO-4Al 2 O 3 -70SiO 2 -5NaF-1KBr-0.01Ag 2 O-0.01CeO 2 (mol%) were studied in this work as in previous works [6][7][8][9]. Technology of glass preparation is described in Ref.…”

“…[9]. Glass samples are fixed to a computer controlled translation stage and moved across the excitation laser beam at constant velocity.…”

“…After laser pulse exposure the glass was heat treated for about 2 h at 515°C to generate the induced refractive index change. The refractive index change was measured using a shearing interferometer setup [9]. Its basic principle is to create an interferogram that relates the index change to a fringe shift.…”

An all-optical scheme of signed digit binary addition based on optical non-linear material

“…Recent researches establish that materials such as photothermo-refractive (PTR) glass, Chalcogenide glass, polymers like polydiacetylenes (a highly conjugated polymer with very large optical nonlinearities) can have good promising aspects in contemplation [6][7][8] . PTR glass can show high nonlinearities and tolerate at least 100 kW/m 2 of CW irradiation by Ybfiber laser at 1085 nm, which is ideal for high power nonlinear devices.…”