Impact of GST thickness on GST-loaded silicon waveguides for optimal optical switching

Abstract

Phase-change integrated photonics has emerged as a new platform for developing photonic integrated circuits by integrating phase-change materials like GeSbTe (GST) onto the silicon photonics platform. The thickness of the GST patch that is usually placed on top of the waveguide is crucial for ensuring high optical performance. In this work, we investigate the impact of the GST thickness in terms of optical performance through numerical simulation and experiment. We show that higher-order modes can be excited in a GST-loaded silicon waveguide with relatively thin GST thicknesses (<100 nm), resulting in a dramatic reduction in the extinction ratio. Our results would be useful for designing high-performance GST/Si-based photonic devices such as non-volatile memories that could find utility in many emerging applications.

A Thermally Reconfigurable Photonic Switch Utilizing Drop Cast Vanadium Oxide Nanoparticles on Silicon Waveguides

“…[ 20 ] Additionally, reducing the concentration of the nanoparticle dropcast solution can decrease nanoparticle density, thereby reducing the device's insertion loss. [ 21–49 ]…”

Phase change materials for integrated photonics

“…3(b) displays the optical transmission of a Si crossing with a 1 µm × 1 µm patch of GST embedded. In this latter case, such a geometry with the GST embedded instead of being placed on top was chosen to optimize the optical switching performance using a "thick" (90 nm) GST patch since GST-loaded silicon waveguide with such GST thickness gives rise to high-order optical modes and large coupling losses 11 . The insulator/metal phase of the VO 2 was controlled using a Peltier, while the GST was changed to the crystalline state by heating the chip at 250 ºC.…”

A Nonvolatile Bipolar Optical Fiber Memory Based on Phase Change Materials

“…Recently, there has been increasing interest in phase change materials such as Ge 2 Sb 2 Te 5 (GST), Ge 2 Sb 2 Se 4 Te, and In 3 SbTe 2 due to their switching and nonvolatile properties. GST, − in particular, is a unique PCM that exhibits significant differences in its electrical and optical properties between its crystalline and amorphous phases and can operate for up to 10 11 cycles. − By adjusting the power of the modulated laser, multilevel control of GST intermediate states can be achieved, and the storage state can be maintained without an additional energy supply . These advantages make GST an excellent candidate for integrated all-photon, quasi-continuous, nonvolatile, multilevel memory and computing, enabling all-photon storage, reading, pattern recognition, and even brainlike neural network computing.…”