title: Experimental observation of evanescent modes at the interface to slow-light photonic crystal waveguides.
abstract: We experimentally study the fields close to an interface between two photonic crystal waveguides that have different dispersion properties. After the transition from a waveguide in which the group velocity of light is v(g) ~ c/10 to a waveguide in which it is v(g) ~ c/100, we observe a gradual increase in the field intensity and the lateral spreading of the mode. We attribute this evolution to the existence of a weakly evanescent mode that exponentially decays away from the interface. We compare this to the situation where the transition between the waveguides only leads to a minor change in group velocity and show that, in that case, the evolution is absent. Furthermore, we apply novel numerical mode extraction techniques to confirm experimental results.
authors.affiliation: Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, 1098 XG, Amsterdam, Netherlands. marko@amolf.nl
authors.forename: Marko
authors.initials: M
authors.lastname: Spasenović
authors.forename: Thomas P
authors.initials: TP
authors.lastname: White
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Ha
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Sukhorukov
authors.forename: Tobias
authors.initials: T
authors.lastname: Kampfrath
authors.forename: Yuri S
authors.initials: YS
authors.lastname: Kivshar
authors.forename: C Martijn
authors.initials: CM
authors.lastname: de Sterke
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Krauss
authors.forename: L Kobus
authors.initials: LK
authors.lastname: Kuipers