RESUMO
CMOS photodiodes are used in many light sensing applications; however, the performance can be limited by oscillations in the spectral response caused by light interference from the back-end oxide. Gray-scale lithography has been used to fabricate wedge-like structures in the back-end oxide, which reduces the light interference and oscillations over the entire silicon sensitivity range. Dielectric filter stacks have been deposited on top of the structures, demonstrating an improved spectral response over photodiodes, with filters deposited directly on silicon. The present approach is suitable for mass production and fully compatible with CMOS.
RESUMO
We launch surface plasmons from one end of a silver nanowire by asymmetric illumination with white light and use plasmon-to-light scattering at the nanowire ends to probe spectroscopically the plasmonic Fabry-Perot wire modes. The spectral positions of the maxima and minima in the scattered intensity from both nanowire ends are found to be either in-phase or out-of-phase, depending on the nanowire length and the spectral range. This behavior can be explained by a generalized Fabry-Perot model. The turnover point between the two regimes is sensitive to the surface plasmon round trip losses and thus opens a new possibility for detecting changes of the optical absorption in the nanowire environment.
RESUMO
We report on a spectroscopic study of surface plasmon damping and group velocity in polycrystalline silver and gold nanowires. By comparing to single-crystalline wires and by using different substrates, we quantitatively deduce the relative damping contributions due to metal crystallinity and absorption in the substrate. Compared to absorbing substrates, we find strongly reduced plasmonic damping for polycrystalline nanowires on quartz substrates, enabling the application of such wires for plasmonic waveguide networks.
