Phase-change materials for Group-IV electro-optical switching and modulation

This paper reviews the invention, design and theoretical simulation of 2 x 2 and 1 x 4 optical routing switches. Insertion loss and crosstalk performance in the 1.55 to 3.0 μm wavelength range are predicted. The electrically actuated optical layer is a thin film of Ge₂Sb₂Te₅ or GeTe or GeSe whose thickness is in the 10 to 100-nm range. This film was embedded at the centerline of an SOI, SON, or GeOI channel waveguide structure for MZI and directional-coupler switching Alternatively, to switch free-space light beams, Ge prisms sandwiching the film were employed. Devices are self-sustaining in each of their two states. Experiments are needed to confirm assumptions made in the theory about voltage requirements, speed, PCM index, and manufacturing techniques.