High performance and CMOS compatible photonic switches based on phase change materials

Abstract

Photonic switches based on phase change materials that are nonvolatile in nature and consume lesser power during switching process while having ultra-low footprint are emerging fast to address the challenges faced by modern interconnects. In addition to optical interconnects and optical communication at 1.55 μm wavelength, such devices are likely to be in great demand for emerging optical communication window around 2 μm wavelength. The switching in phase change materials can be triggered by electrical, optical or thermal means. One such material Ge2Sb2Te5 is technologically mature, cost effective and compatible with CMOS fabrication technology. It can exist in amorphous as well as crystalline phase and remains stable in both the phases. It can be switched rapidly and repeatedly for realizing photonic switching devices around wavelengths 1.55 μm and 2.0 μm. By integrating Ge2Sb2Te5 on silicon-on-insulator platform, the switching functionalities with high performance can be achieved. Here, we present various types of switches based on different hybrid Ge2Sb2Te5-Silicon waveguide. Different geometries will be discussed for operational wavelengths of 1.55 μm and 2.0 μm. Different design strategies that lead to realization of high performance photonic switches in terms of extinction ratio, insertion loss, switching energy and re-configurability using ultra-compact Ge2Sb2Te5 embedded within the silicon waveguide and having indium tin oxide electrodes are described in detail.