title: Confinement and guiding of two-dimensional optical waves by low-refractive-index cores.
abstract: A new method for confining and guiding two-dimensional (2D) optical waves is proposed using low-refractive-index materials as cores of metal-gap waveguides. A proper choice of the refractive index of claddings prohibits 2D optical waves from propagating inside the claddings, resulting in strong confinement of waves inside the low-refractive-index cores. We numerically demonstrate that this new method for guiding 2D optical waves can achieve stronger confinement than the conventional one using high-refractive-index cores. This strong confinement leads to efficient guiding of 2D optical waves not only at straight path, but also at sharp 90 degrees bends with negligible radiation losses.
authors.forename: F
authors.initials: F
authors.lastname: Kusunoki
authors.forename: T
authors.initials: T
authors.lastname: Yotsuya
authors.forename: J
authors.initials: J
authors.lastname: Takahara