Antimony as a Programmable Element in Integrated Nanophotonics

The use of nonlinear elements with memory as photoniccomputing components has seen a huge surge in interest in recent yearswith the rise of artificial intelligence and machine learning. A keycomponent is the nonlinear element itself. A class of materials known asphase change materials has been extensively used to demonstrate theviability of such computing. However, such materials continue to haverelatively slow switching speeds, and issues with cyclability related tophase segregation of phase change alloys. Here, using antimony (Sb)thinfilms with thicknesses less than 5 nm we demonstrate reversible,ultrafast switching on an integrated photonic platform with retentiontime of tens of seconds. We use subpicosecond pulses, the shortest usedto switch such elements, to program seven distinct memory levels. This portends their use in ultrafast nanophotonic applicationsranging from nanophotonic beam steerers to nanoscale integrated elements for photonic computing