Multistate non-volatile photonic memory devices are disclosed. The photonic devices comprise phase change materials with broadband transparencies used to store discretized information with negligible losses in the 0 state. The photonic memories comprise multiple configurations for reading and writing multi-bit words. The reading mechanisms comprises schemes based on light-absorption (FIG. 1), shift in resonances of a cavity (ring resonator, photonic crystal; FIG. 2) or interferometric schemes (FIG. 3). The photonic memory devices employ multiple techniques for writing electrically (FIG. 4 and related performance) and/or all-optically (FIGS. 7-10). The optical writing can be performed with pulsed laser light coming either from free space or on-chip using dedicated writing lines and opportune drops.

Multistate non-volatile photonic memory devices are disclosed. The photonic devices comprise phase change materials with broadband transparencies used to store discretized information with negligible losses in the 0 state. The photonic memories comprise multiple configurations for reading and writing multi-bit words. The reading mechanisms comprises schemes based on light-absorption (FIG. 1), shift in resonances of a cavity (ring resonator, photonic crystal; FIG. 2) or interferometric schemes (FIG. 3). The photonic memory devices employ multiple techniques for writing electrically (FIG. 4 and related performance) and/or all-optically (FIGS. 7-10). The optical writing can be performed with pulsed laser light coming either from free space or on-chip using dedicated writing lines and opportune drops.