Electro-optical switching at 1550 nm using a two-state GeSe phase-change layer

New designs for electro-optical free-space and waveguided 2 x 2 switches are presented and analyzed at the 1.55 mu m telecoms wavelength. The proposed devices employ a mu 10 nm film of GeSe that is electrically actuated to transition the layer forth-and-back from the amorphous to the crystal phase, yielding a switch with two self-sustaining states. This phase change material was selected for its very low absorption loss at the operation wavelength, along with its electro-refraction Delta n similar to 0.6. All switches are cascadeable into N x M devices. The free-space prism-shaped structures use III-V prism material to match the GeSe crystal index. The Si/GeSe/Si active waveguides are quite suitable for directional-coupler switches as well as Mach-Zehnder devices-all of which have an active length 16x less than that in the free-carrier art. (C) 2015 Optical Society of America