Simulations of Silicon-on-Insulator Channel-Waveguide Electrooptical 2 x 2 Switches and 1 x 1 Modulators Using a Ge2Sb2Te5 Self-Holding Layer

This paper reports theoretical designs and simulations of electrooptical 2 x 2 switches and 1 x 1 loss modulators based upon GST-embedded SOI channel waveguides. It is assumed that the amorphous and crystalline phases of GST can be triggered electrically by Joule heating current applied to a 10-nm GST film sandwiched between doped-Si waveguide strips. TEo and TMo mode effective indices are calculated over 1.3 to 2.1-mu m wavelength range. For 2 x 2 Mach-Zehnder and directional coupler switches, low insertion loss, low crosstalk, and short device lengths are predicted for 2.1 mu m, although a decreased performance is projected for 1.55 mu m. For 1.3-2.1 mu m, the 1 x 1 EO waveguide has application as a variable optical attenuator and as a digital modulator, albeit with <= 100-ns state-transition time. Because the active material has two stable phases, the device holds itself in either state, and voltage needs to be applied only during transition.