Optical non-linearities (ONL) have been studied in a-Si:H and a-Se thin films by putting the films in or near the caustic of highly-focused laser beams at sub-band gap energies, while the beam intensity is periodically altered by an electro-optic modulator. In a-Si:H non-linear absorption is seen, together with non-linear refraction of the laser beam at the highest intensities. In the a-Se samples additional, persistent ONL due to structural modifications of the films are observed. They include the appearance of interference fringes and modulation of the reflectance due to the formation of microlenses.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry