Graphene is an attractive material for all-optical modulation because of its ultrafast optical response and broad spectral coverage. However, all-optical graphene modulators reported so far require high pump fluence due to the ultrashort photo-carrier lifetime and limited absorption in graphene. We present modulator designs based on graphene-metal hybrid plasmonic metasurfaces with highly enhanced light- graphene interaction in the nanoscale hot spots at pump and probe (signal) wavelengths. Based on this design concept, we have demonstrated high-speed all optical modulators at near and mid-infrared wavelengths (1.56 um and above Gum) with significantly reduced pump fluence (1-2 orders of magnitude) and enhanced optical modulation. Ultrafast near-infrared pump-probe measurement results suggest that the modulators' response times are ultimately determined by graphene's ultrafast photocarrier relaxation times on the picosecond scale. The proposed designs hold the promise to address the challenges in the realization of ultrafast all-optical modulators for mid-and far-infrared wavelengths.
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2D Crystal Consortium - Materials Innovation Platform (2DCC-MIP)
The 2DCC-MIP combines a vibrant in-house research effort focused on transformative advances in the synthesis and characterization of 2D chalcogenide layered materials with a robust external user program that provides access to expertise and state-of-the-art facilities. The 2DCC-MIP platform enables cutting edge research and discovery, across in-house research and the user program, on the synthesis and characterization of 2D chalcogenide materials by a national user community guided by four science drivers: Physics of 2D Systems, Epitaxy of 2D Chalcogenides, Next-generation 2D Electronics, and Advanced Characterization and Modeling.