Phase Change Materials for Reconfigurable Nanophotonic Applications

Nanophotonics has garnered intensive interests owing to its unique capabilities on unprecedented manipulation of light in the subwavelength regime for high speed and large bandwidth information transmission and computation. However, to rival electronics in terms of integratability and reprogrammability, nanophotonics must evolve into the next generation miniaturized and reconfigurable platforms with tunable properties on demand. Chalcogenide phase-change materials (PCMs), which retain the ‘memory’ of sub-threshold excitations and enable multiple-step gradual phase transition, have been identified as a promising platform for tunable and reconfigurable nanophotonic frameworks for ubiquitous functionalities from imaging and communication to sensing. In our work, we explore the multi-level optical phase transition of chalcogenide phase change material, Germanium-antimony-tellurium (GST), induced by femtosecond laser pulses. The pixilated phase change of GST in sub-micro marks results in a dramatic change in optical properties from amorphous to crystalline states. Various applications are demonstrated including high density data storage, re-writable flat photonics metamaterial, reconfigurable phase change photomask, and multi-step tuning of third harmonic generation. It is believed that the such reconfigurable mechanism of phase change materials will advance photonics in the next-generation light-related applications e.g. all-optical neuromorphic computing, adaptive optics, imaging/display, and engineering, etc.<br/><b>Acknowledgements: </b>This work is partially supported by the Agency for Science, Technology and Research (A*STAR) under AME IRG Grant Nos. A20E5c0095, and CDF Grant No. C210112044.