A Novel Versatile Electrically Erasable Programmable Read-Only Grating

Programmable photonics is expected to become a cornerstone of modern photonic systems. This manuscript presents a novel programmable optical device named Electrically Erasable Programmable Read-Only Grating (EEPROG). The device consists of a programmable grating enabling several functionalities. The device is made of a Si₃N₄ waveguide and a thin layer of phase-change materials (PCM), specifically Sb₂S₃, as the programmable part of the waveguided structure. The electrically induced phase change of the PCM, applied by means of a graphene-based microheater, leads to a local variation of the effective refractive index of the waveguide. By controlling a series of graphene-based microheaters, we demonstrate that it is possible to induce periodic or nonperiodic perturbations of the effective refractive index of the device waveguide along the direction of propagation, thus inducing specific programmable operations of the structure. For the first time to our knowledge, a non-volatile programmable grating is shown, with the possibility of individually programming each segment of the grating, to induce both periodic and non-periodic grating, thus enabling several applications. In the manuscript, optical and thermal simulations of the device are shown to demonstrate the feasibility of the device. The EEPROG represents a novel device, useful for several applications, ranging from filtering to neural networks, Optical Transfer Function Shaping and non-volatile programmable read-only memories.