Diatoms are a group of single-celled photosynthetic algae that make skeletal shells of hydrated amorphous silica, called
frustules, which possess hierarchical nanoscale photonic crystal features made by a bottom-up approach at ambient
temperature and pressure. In this paper, we theoretically investigate electric field enhancements of plasmonic
nanoparticles coated on the surface of diatom skeletal shells. Surface-Enhanced Raman Scattering substrates are
prepared by evaporating 10 nm thick silver film and self-assembling silver nanoparticles on diatom surfaces, which show
significantly better SERS signals than silver nanoparticles on flat glass substrates.
A liquid crystal infiltrated spiral photonic crystal fiber (LCSPCF) is presented here for electrical tuning of two zero
dispersion wavelengths (ZDWs) in the present communication window. The proposed LCSPCF shows tunability of the
ZDWs from 1433 nm to 2136 nm due to the rotation of the infiltrated LC mesogen induced by the external electric field.
Therefore, the ZDW can easily be shifted towards the available pump wavelength for effective supercontinuum
generation (SCG) over a broad wavelength region. By tuning the bandwidth (BW) in between the two ZDWs the
extension of the generated supercontinuum (SC) spectrum can also be electrically controlled. This will help the SCG in
our desired band with optimum power budget. Moreover, the index guiding mechanism of the proposed soft glass
LCSPCF shows improvement over the narrow operational bandwidth and the low nonlinearity of the band-gap guided
silica LCPCF. Additionally, the solid core of the proposed LCSPCF is less lossy than the previously proposed liquid
crystal core PCF.
A silica spiral photonic crystal fiber is presented here for tailoring two zero dispersion wavelengths (ZDWs) in the visible region. The proposed fiber has two ZDWs (523.1 and 716.8 nm) along with a very high nonlinearity parameter (1060 W−1 km−1 at 500 nm) around the visible region. The proposed design shows improvement over the group dispersion control and air holes collapsibility of highly air filled hexagonal photonic crystal fiber (HPCF), and low damage threshold of the soft glass photonic crystal fiber. Besides, the low air filling fraction (≈43%) of the proposed design reduces the probability of sustaining higher order modes in the fiber and also ensures easy fabrication due to fewer air holes.