Plasmonic Fano-Metasurfaces for Optical Signal Processing

Nanohmics Inc. in collaboration with Dr. Andrea Al propose to develop and experimentally demonstrate ultra-compact nonlinear-plasmonic all-optical switches and isolators that exploit sharp asymmetric plasmonic-resonances observed in sub-wavelength metasurfaces. Devices will be comprised of plasmonic gratings that couple light into Long Range Surface Plasmons (LRSPs). The gratings are engineered to have sharp asymmetric Fano-resonance. The grating structures will be embedded in a nonlinear medium with large third-order susceptibility. Through the Kerr effect, the intensity of the input light can be varied to tune the signal wavelength across the Fano-resonance, thereby sharply modulating the reflectance, akin to an all-optical switch. In an alternative embodiment, an optical isolator can be created by designing a structural asymmetry in the device such that light approaching the device terminals from opposite ends have starkly different transmission. The proposed devices will operate at telecommunication wavelengths, have a 5 micron-square footprint or smaller, have a 3-dB insertion loss or better, and require modest optical power in the tens of MW/cm^2 to operate. All-optical switches will aim to achieve at least 10-dB contrast between the on and off states and switching speeds better than 1 ns. Isolators will have at least 10-dB isolation between forward and reverse-propagating waves.