Reconfigurable Flat Optics with Programmable Reflection Amplitude Using Lithography-Free Phase-Change Materials Ultra Thin Films

We experimentally demonstrate a very large dynamic optical reflection modulation from a simple unpatterned layered stack of phase-change materials ultrathin films. Specifically, we theoretically and experimentally demonstrate that properly designed deeply subwavelength GeSbTe (GST) films on a metallic mirror produce a dynamic modulation of light in the near-infrared from very strong reflection (R>80%) to perfect absorption (A > 99,97%) by simply switching the crystalline state of the phase-change material. While the amplitude of modulation can lead to an optical contrast up to 10^6, we can also actively "write" intermediate levels of reflection in between extreme values, corresponding to partial crystallization of the GST layer. We further explore several layered system designs and provide guidelines to tailor the wavelength efficiency range, the angle of operation and the degree of crystallization leading to perfect absorption

Reconfigurable Flat Optics with Programmable Reflection Am- plitude Using Lithography-Free Phase-Change Materials Ultra Thin Films

International audienceWe experimentally demonstrate a very large dynamic optical reflection modulation from a simple unpatterned layered stack of phase-change materials ultrathin films. Specifically, we theoretically and experimentally demonstrate that properly designed deeply sub-wavelength GeSbTe (GST) films on a metallic mirror produce a dynamic modulation of light in the near-infrared from very strong reflection (R > 80%) to perfect absorption (A > 99, 97%) by simply switching the crystalline state of the phase-change material. While the amplitude of modulation can lead to an optical contrast up to 10 6 , we can also actively "write" intermediate levels of reflection in between extreme values, corresponding to partial crystallization of the GST layer. We further explore several layered system designs and provide guidelines to tailor the wavelength efficiency range, the angle of operation and the degree of crystallization leading to perfect absorption

Simulation-based Comparison of the Performance of Various Phase-Change Materials on a SiN-based Photonic Platform

International audienceWe present a simulation-based performance assessment of various phase-change materials (PCMs) in the context of photonic integrated circuits. We study a device consisting of a thin rectangular patch of PCM deposited on a silicon nitride waveguide. This device is programmed using guided optical pulses to alter its optical transmission by partially changing the phase of the PCM. Using two application-aware figures of merit, we evaluate the programming efficiency for each PCM considered