Sub-micrometer-thick ,and low-loss Ge20Sb5Se65 rib waveguides for nonlinear optical devices

We report the fabrication and optical properties of sub-micrometer-thick Ge20Sb15Se65 chalcogenide rib waveguides. The radio-frequency （R.F） magnetron sputtering method is used to deposit 0.83 lain-thick films. A protective layer of SU-8 is employed to prevent the attack of the alkaline developer, and CHF3 is used as the etching plasma for reactive ion etching （RIE）. Finally, the resulted rib waveguides with smooth sidewalls and vertical pattern profiles are rendered. The propagation losses for 4 pan-wide waveguides are measured to be 0.7 dB/cm for transverse electric （TE） modes and 0.68 dB/em for transverse magnetic （TM） modes at 1 550 nm via the cutback method.