Time-Resolved Temperature Mapping Leveraging the Strong Thermo-Optic Effect in Phase-Change Materials

Abstract

Optical phase-change materials are highly promising for emerging applications such as tunable metasurfaces, reconfigurable photonic circuits, and non-von Neumann computing. However, these materials typically require both high melting temperatures and fast quenching rates to reversibly switch between their crystalline and amorphous phases: a significant challenge for large-scale integration. In this work, we use temperature-dependent ellipsometry to study the thermo-optic effect in GST and use these results to demonstrate an experimental technique that leverages the thermo-optic effect in GST to enable both spatial and temporal thermal measurements of two common electro-thermal microheater designs currently used by the phase-change community. Our approach shows excellent agreement between experimental results and numerical simulations and provides a noninvasive method for rapid characterization of electrically programmable phase-change devices.

Electrically Reconfigurable Phase Change Material-Based Metamaterial Absorber for Broadband Molecular Fingerprint Retrieval

“…By fitting eq with the temporal temperature profile shown in Figure c, we obtain time constants τ h = 179 ns and τ c = 139 ns. Thus, the proposed microheater has a fast response and can be used for the crystallization of GST . Also, it is to be noted that recently, Taute et al have demonstrated that multilevel crystallization can be achieved by fixing the temperature close to the onset of crystallization temperature and letting GST crystallize as a function of time.…”

“…Thus, the proposed microheater has a fast response and can be used for the crystallization of GST. 15 Also, it is to be noted that recently, Taute et al 12 have demonstrated that multilevel crystallization can be achieved by fixing the temperature close to the onset of crystallization temperature and letting GST crystallize as a function of time. This way of crystallizing GST circumvents the thermo-optical effect of other elements in the structure.…”

“…Recent advancements have involved the integration of metal microheaters to actively modulate the phase of GST. Applying voltage pulses through these microheaters induces the joule heating effect, enabling controlled heating of PCM and thereby achieving a fully integrable metamaterial absorber. − …”