title: Direct femtosecond laser writing of waveguides in As2S3 thin films.
abstract: Single-channel waveguides and Y couplers were fabricated in chalcogenide thin films by use of femtosecond laser pulses from a 25-MHz repetition rate Ti:sapphire laser. Refractive-index differentials (delta n > 10(-2)) were measured through interferometric microscopy and are higher than the typical values reported for oxide glasses. The dependence of the index differential on the peak intensity reveals the nonlinear nature of the photosensitivity in arsenic trisulfide below its bandgap energy, and the refractive-index change is correlated to the photoinduced structural changes inferred by Raman spectroscopy data. A free-electron model to predict the parametric dependence of delta n is proposed.
authors.affiliation: School of Optics and Center for Research and Education in Optics and Lasers, University of Central Florida, Orlando, Florida 32816, USA. azoubir@mail.ucf.edu
authors.forename: Arnaud
authors.initials: A
authors.lastname: Zoubir
authors.forename: Martin
authors.initials: M
authors.lastname: Richardson
authors.forename: Clara
authors.initials: C
authors.lastname: Rivero
authors.forename: Alfons
authors.initials: A
authors.lastname: Schulte
authors.forename: Cedric
authors.initials: C
authors.lastname: Lopez
authors.forename: Kathleen
authors.initials: K
authors.lastname: Richardson
authors.forename: Nicolas
authors.initials: N
authors.lastname: Hô
authors.forename: Réal
authors.initials: R
authors.lastname: Vallée