The Role of Photo-Striction in Tailoring the Nano-Scale Phase Changes in Amorphous Selenium Thin Films

The photo-structural changes in a 2 μm thick amorphous selenium (a-Se) thin film, thermally evaporated on Si substrate, have been studied by micro-Raman spectrometer with 532 nm laser at different laser power densities (1 to 64 W/mm 2 ) and exposure times (15 – 60 s). In addition, the nanoscale photo-structural changes/photo-thermodynamic phase changes are examined on 90 nm a-Se film coated on SiO 2 cladding of the optical Fiber Bragg Grating (FBG) sensor on prolonged exposure to a low power (1 mW/mm 2 , 10 mW/mm 2 ) 532 nm laser, which is measured by means of photo-striction (light induced strain) in the material.