Bragg gratings in a new photosensitive material - photo-thermo-refractive glass

摘要

A new material for optics is being developed that promises to be far more robust than alternative materials. It is a photo-thermo-refractive (PTR) glass in which Bragg gratings can be written in the interior of the glass. The gratings are permanent as they are not removed by illuminating them with light at other wavelengths or by heating unless the temperature exceeds 400 C. This technology can be used to make diffractive elements such as spatial filters, attenuators, switches, modulators, beam splitters, beam samplers, beam deflectors, selectors of particular wavelengths (notch filters, add/drop elements), spectral shape formers (gain equalizers), spectral sensors, angular sensors, Bragg spectrometers, and transverse and longitudinal mode selectors in a laser resonator. The useful spectral range of this glass is from 350 nm to 2.8 microns.