Ge2Sb2Se4Te (GSST) Phase Change Material Monolithic Platform for Integrated Photonics

by Niloy Acharjee

May 3, 2024 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Advisor: Professor Gary Rubloff

Recently, the non-volatile nature and large variation of optical properties (i.e., complex refractive index) between at least two different phases of Phase-Change Materials (PCMs) made them attractive to actively control the amplitude and phase of light on different photonic platforms. While exploited in several applications since its demonstration in 2019, amorphous GSST—a PCM featuring a large refractive index at 1550 nm (n=3) and a 1.5 change in index upon crystallization—has never been used as a monolithic platform for photonic integrated circuits (PICs). Building such a platform with PCMs allows monolithic active photonic devices since changing the phase of the material enables tuning the refractive index and the electrical conductivity. Thus, post-fabrication trimming and writing of photonic structures to control light and even the integration of microheaters for thermo-optical modulation can all be achieved on the same material platform via localized crystallization. In this presentation, I will demonstrate a proof-of-concept of GSST photonic integrated circuits and a writing mechanism based on electron-beam-induced crystallization.

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