科研之友
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摘要
Taking advantage of the Kerr nonlinearities of metallic nanolayers and graphene (G) and the well-known pump probe method, we show that 200-nm-wide slabs of hyperbolic metamaterial (HMM) composed of 14 vertically stacked unit cells can be switched all optically between the negative refraction regime (ON state) and the no-transmission regime (OFF state), when illuminated by appropriately chosen TE-polarized Gaussian pump and TM-polarized CW probe. Finite element method numerical simulations show that the HMM slab with unit cells made of Au/Al2O3 nanolayers suffering from a relatively large plasmonic loss exhibits an ON state transmittance spectrum limited to 52%-72% over the visible range of 585-600 nm, when a 500 V/mu m pump signal is utilized. Similar numerical results obtained for the HMM slab whose unit cells are made of Au/Al2O3/G/Al2O3/Au nanolayers show that a 4 V/mu m pump signal is enough to stimulate the Kerr effect, resulting in a similar to 97% ON state transmittance over the ultra-narrowband of 803-805 nm. Moreover, simulations show that when the unit cells are made of Ag/Si/G/Si/Ag nanolayers, a 95-nm-wide ON state transmittance of 49%-99% over the IR range of 800-895 nm can be obtained with a 19.5 V/mu m pump. The proposed HMM structures can be used as all-optical switches in future optical digital systems.
