Nonvolatile Reconfigurable Phase-Change Metadevices for Beam Steering in the Near Infrared

The development of flat, compact beam-steering devices with no bulky moving parts is opening up a new route to a variety of exciting applications, such as LIDAR scanning systems for autonomous vehicles, robotics and sensing, free-space, and even surface wave optical signal coupling. In this paper, the design, fabrication and characterization of innovative, nonvolatile, and reconfigurable beam-steering metadevices enabled by a combination of optical metasurfaces and chalcogenide phase-change materials is reported. The metadevices reflect an incident optical beam in a mirror-like fashion when the phase-change layer is in the crystalline state, but reflect anomalously at predesigned angles when the phase-change layer is switched into its amorphous state. Experimental angle-resolved spectrometry measurements verify that fabricated devices perform as designed, with high efficiencies, up to 40%, when operating at 1550 nm. Laser-induced crystallization and reamorphization experiments confirm reversible switching of the device. It is believed that reconfigurable phase-change-based beam-steering and beam-shaping metadevices, such as those reported here, can offer real applications advantages, such as high efficiency, compactness, fast switching times and, due to the nonvolatile nature of chalcogenide phase-change materials, low power consumption.