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.
A new window of optical communication is emerging around 2 μm. It is important to design and experimentally demonstrate the photonic devices and components that can support the optical communication in this spectral region by providing the functionalities of switching and routing. The silicon photonics platform for realizing the photonic devices and components will be preferred around 2 μm, like other optical communication windows of 1310 nm and 1550 nm, due to availability of cost effective and high yield CMOS fabrication technology. Photonic switches that are non-volatile in nature and consume lesser power while having ultra-low footprint are likely to be in great demand for future optical communication around 2 μm. Here, we report an ultra-compact 1×1 photonic switch operating at 2.1 μm using nonvolatile phase change material Ge2Sb2Te5 embedded in silicon-on-insulator platform. Embedding of Ge2Sb2Te5in silicon-on-insulator waveguide is done in two different ways to evaluate and compare the switching performance. The emphasis has been on optimization of position and dimensions of Ge2Sb2Te5 in partially and fully etched silicon waveguide. We obtained an extinction ratio of 34.04 dB with low insertion loss of 0.49 dB in ON state with Ge2Sb2Te5 of volume 920 nm× 240 nm × 800 nm (length × height × width) embedded into partially etched silicon waveguide. When Ge2Sb2Te5 is embedded in fully etched silicon waveguide, maximum extinction ratio of ~14dB at the expense of insertion loss of 1.36 dB with Ge2Sb2Te5 of volume 1020 nm× 240 nm × 800 nm.