Multi-level Optical Switching by Amorphization in Single- and Multi- Phase Change Material Structures

TL;DR

This paper demonstrates multi-level optical switching in phase-change materials using laser pulses, achieving 16 levels in Ge2Sb2Te5 and four levels in multi-material structures, advancing dynamic photonics applications.

Contribution

It introduces a detailed analysis of reversible multi-level optical switching in single and multi-material PCM structures with experimental validation.

Findings

16 reflectance levels in Ge2Sb2Te5 achieved via amorphization

Reversible multi-level switching demonstrated in Ge2Sb2Te5 and GeTe structures

Design principles for multi-level optical switches provided

Abstract

The optical properties of phase-change materials (PCM) can be tuned to multiple levels by controlling the transition between their amorphous and crystalline phases. In multi-material PCM structures, the number of discrete reflectance levels can be increased according to the number of PCM layers. However, the effect of increasing number of layers on quenching and reversibility has not been thoroughly studied. In this work, the phase-change physics and thermal conditions required for reversible switching of single and multi-material PCM switches are discussed based on thermo-optical phase-change models and laser switching experiments. By using nanosecond laser pulses, 16 different reflectance levels in Ge2Sb2Te5 are demonstrated via amorphization. Furthermore, a multi-material switch based on Ge2Sb2Te5 and GeTe with four discrete reflectance levels is experimentally proven with a reversible multi-level response. The results and design principles presented herein will impact active photonics applications that rely on dynamic multi-level operation, such as optical computing, beam steering, and next-generation display technologies.