Direct femtosecond laser writing of waveguides in As2S3 thin films.
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.
Zoubir
Arnaud
A
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
Richardson
Martin
M
Rivero
Clara
C
Schulte
Alfons
A
Lopez
Cedric
C
Richardson
Kathleen
K
Hô
Nicolas
N
Vallée
Réal
R