Laser-induced damage studies in silicon and silicon-based photodetectors.

Laser-induced damage studies have been carried out on single-crystal silicon and silicon-based photodetectors, FND 100 P-I-N photodiodes, and C30954E avalanche photodiodes as a function of repetition frequency for a 1064-nm wavelength. It has been observed that the damage threshold decreases significantly when the samples are irradiated with a large number of pulses. However, this effect is evident only when the repetition frequency is greater than 1 Hz. The results are discussed in light of various existing theories.

Fabrication and characterization of dye doped polyester-polyurethane optical waveguides.

A systematic study of the fabrication and characterization of planar optical waveguides based on polyester-polyurethane coatings was done. Mode effective refractive index measurements were performed on a large number of these waveguides fabricated on glass substrates prepared in different conditions. The results indicate that the effect of the dye is to increase the refractive index of the waveguides. The losses in the guides, however, initially decreased from 0.9 to approximately 0.5 dB/cm when the dye concentration was approximately 0.1% but increased drastically (>30 dB/cm) for guides with greater dye concentrations.

Effect of uv exposure on optical properties of amorphous as(2)s(3) thin films.

Systematic studies of the refractive index, extinction coefficient, and optical band gap have been made of as grown and UV-exposed amorphous films of As(2)S(3) grown by thermal evaporation from resistive source. The refractive index and extinction coefficient have been found to change with different UV exposure duration. No noticeable change was observed in the optical band gap with UV exposure.

Fabrication and characterization of polyester and acrylic polyurethane optical waveguides.

Asystematic study of the fabrication and characterization of planar optical waveguides based on polyester and acrylic polyurethane coatings has been made. Mode effective refractive-index measurements have been made on a large number of these waveguides fabricated on glass prepared in different conditions. The results show that the mixture of polyester and acrylic polyol in the initial solution can be used to control the refractive index from 1.563 to 1.595. The propagation losses are estimated to be 10-20 and 6-12 dB/cm for polyester and acrylic-based waveguides, respectively.