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...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(1.56μm and above 6μm)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.展开更多
基金supported in part by the AFOSR YIP under Grant no.FA9550–16–1–0183the National Science Foundation under grant ECCS1809997+2 种基金2DCC-MIP national user facility under Grant noDMR-1539916,and Arizona State University startup funds provided to Y.Y.by the NSF contract ECCS-1542160.
文摘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(1.56μm and above 6μm)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.
