All-optical programmable photonic integrated circuit: An optical analogy to electronic FPGA

An all-optical, programmable photonic integrated circuit platform is developed by leveraging the advantages of three techniques: two-dimensional silicon photonic crystals, digital micromirror devices, and photo-responsive liquid crystals. The employment of a light spatial modulator enables us to address any air holes of a photonic crystal slab infiltrated with liquid crystals, modulating flexibly the effective refractive index of each photonic cell. By optically introducing multiple point defects to different regions of the photonic crystal slab through digital programming, it is possible to reconfigure and tune various photonic building blocks, interconnects, and even complex photonic circuits on a single chip. Using this device, we have demonstrated to realize three basic photonic components, including a straight waveguide, a waveguide bend, and a cavity filter.