Giant enhancement in Goos-Hanchen shift at the singular phase of a nanophotonic cavity

In this letter, we experimentally demonstrate thirtyfold enhancement in Goos-Hanchen shift at the Brewster angle of a nanophotonic cavity that operates at the wavelength of 632.8 nm. In particular, the point-of-darkness and the singular phase are achieved using a four-layered metal-dielectricdielectric- metal asymmetric Fabry-Perot cavity. A highly absorbing ultra-thin layer of germanium in the stack gives rise to the singular phase and the enhanced Goos-Hanchen shift at the point-ofdarkness. The obtained giant Goos-Hanchen shift in the lithography-free nanophotonic cavity could enable many intriguing applications including cost-effective label-free biosensors. Published by AIP Publishing.