Writing Speed Dependency of Femtosecond Laser Refractive Index Modification in Poly(dimethylsiloxane)

This report describes the filamentary refractive index change under slow-focusing conditions in polydimethylsiloxane using femtosecond pulses from a 1-kHz Ti:sapphire amplifier.The respective influences of laser writing parameters and focusing conditions were studied.The refractive index change was induced by scanning the sample up to 4 mm/s.The refractive index change with a magnitude of 2.3×10 -4 was estimated from the diffraction efficiencies of a volume grating with 300 µm thickness.