title: Reversibly tunable plasmonic bandgap by responsive hydrogel grating.
abstract: Reversible actuating of surface plasmon propagation by responsive hydrogel grating is reported. Thermo-responsive poly(N-isopropylacrylamide)-based (pNIPAAm) hydrogel nanostructure was designed and tethered to a gold surface in order to switch on and off Bragg scattering of surface plasmons which is associated with an occurrence of a bandgap in their dispersion relation. pNIPAAm-based grating with a period around 280 nm was prepared by using photo-crosslinkable terpolymer and laser interference lithography and it was brought in contact with water. The temperature induced swelling and collapse of pNIPAAm hydrogel grating strongly modulates its refractive index (Δn~0.1) which leads to the reversible opening and closing of a plasmonic bandgap. The experiments demonstrate partial opening of a bandgap with the width of 12 nm at wavelength around 800 nm where SPR exhibited the spectral width of about 75 nm.
authors.forename: Nityanand
authors.initials: N
authors.lastname: Sharma
authors.forename: Christian
authors.initials: C
authors.lastname: Petri
authors.forename: Ulrich
authors.initials: U
authors.lastname: Jonas
authors.forename: Jakub
authors.initials: J
authors.lastname: Dostalek