Temporal Coding of Incident Light on Phase‑Change Plasmonic Surfaces for Adaptive Optical Memory Storage
Viyat Varun Updhay· N. Nagabhooshanam · Sharad Rathore · Madan Lal. A. C. Santha Sheela6 · D. Beulah· A. Rajaram
https://doi.org/10.1007/s11468-025-03218-7
The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025
Abstract
A recongur able phase-change photonic platform is demonstrated that combines Ge2Sb2Te5 (GST) with plasmonic bowtie nanoantennas, which can achieve sub-nanosecond, multi-level optical memory and logic operations. Sputtered GST lms as thin as 20–50 nm were found to be exceedingly uniform, with root-mean-square (RMS) roughness of 0.45–0.65 nm, comparable to the best standards. Gold nanoantennas with sub-10 nm resolution were fabricated by high-precision electron beam lithography to guarantee maximum light connement. Localized sur face plasmon resonances (LSPR) were switched between 825 and 1525 nm, and simulations indicated electric eld enhancements of | E/E 0|= 18.2 × . Excitation with femtosecond pulses produced phase transitions at a uence t hreshold of 0.18 µJ/µm 2 (crystallization) and temperatures above 850 K (amorphization), and the reect ance modulation was measured to be as large as 35%. The refractive index (n) and extinction coecient ( k) ranged between 3.8 and 6.6 and 0.12 to 2.5, respectively, and electrical conductivity changed by ~ 104-fold across phase transitions. Localized peak temperatures of ~ 465 K were predicted by COMSOL simulations, and ultrafast, interface-controlled kinetics were suggested by Avrami exponents (1.925) in good agreement with molecular dynamics calculations, and crystallization times were found to be between 180 and 250 ps. Memory mapping showed four stable reect ance levels with > 8% spacing and > 10,000 cycle endurance. Photonic logic gates (AND, OR and XOR) were achieved, which demonstrated sub-ns switching and improved non-volatility. The platform enables scalable, high-speed optoelectronic control of next-generation memory and computing systems.
PCM layerFig. 1 Plasmonic nanoantenna-induced nanoscale phase switching in
