We show, via simulations, that an optical fiber taper waveguide may be an efficient spectroscopy tool for single emitters, such as single molecules or colloidal quantum dots, deposited on the surface of a thin dielectric membrane. The fiber-membrane system supports modes akin to those of a slotted dielectric waveguide, providing strong field confinement in the low index gap region, and leading to the potential for high spontaneous emission enhancement factors ( ≅ 20), fluorescence collection efficiencies ( ≅ 23%), and transmission extinction ( ≅ 20%) levels. A factor of two improvement in fluorescence and extinction levels is predicted if the membrane is instead replaced with a suspended channel waveguide. Two configurations, for operation in the visible ( ≅ 600 nm) and near-infrared ( ≅ 1300 nm) spectral ranges are evaluated, presenting similar performances.
Citation: Optics Express
Pub Type: Journals
Nanophotonics and photonic crystals , quantum optics