Stimulated Brillouin scattering amplification in centimeter-long directly written chalcogenide waveguides

Stimulated Brillouin scattering (SBS) amplification is obtained in directly written As2S3 channel waveguides. Centimeter-long waveguides were written using a Ti:sapphire femtosecond laser, operating at a central wavelength of 810 nm. The cross-section of the waveguides was of 4  μm×1  μm. A Brillouin frequency shift of 7.5 GHz is observed, in general agreement with corresponding previous studies. The SBS gain spectrum in the short waveguides is comparatively broad, with a full width at half-maximum of 200 MHz. We attribute the broad linewidth to the spatial evolution of the electromagnetic field profile along the waveguide.