Pankaj K. Sahoo

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We present experimental demonstration and analysis of enhanced surface second harmonic generation (SHG) from hexagonal arrays of silicon pillars. Three sets of Si pillar samples with truncated cone-shaped pillar arrays having periods of 500, 1000, and 2000 nm, and corresponding average diameters of 200, 585 and 1550 nm, respectively, are fabricated by(More)
An optical diode that uses nonlinear ring resonators in 2D photonic crystal is numerically simulated by using the finite-difference time-domain (FDTD) method. Nonlinear polystyrene is used as the Kerr medium forming ring resonators. The operating wavelength of the optical diode is considered to be the coupling wavelength at which light couples efficiently(More)
We report an ultra-sensitive refractive index (RI) sensor employing phase detection in a guided mode resonance (GMR) structure. By incorporating the GMR structure in to a Mach-Zehnder Interferometer, we measured the phase of GMR signal by calculating the amount of fringe shift. Since the phase of GMR signal varies rapidly around the resonance wavelength,(More)
We present a technique for refractive index sensing using a phase grating structure. A grating under normal incidence can be designed such that the first-order diffracted light travels at a diffraction angle of 90° with respect to the zeroth order. The diffracted light, which is along the direction of periodicity, can further be diffracted from the grating(More)
InAs nanowires grown by vapor-liquid-solid (VLS) method are investigated by photoluminescence. We observe that the Fermi energy of all samples is reduced by ∼20 meV when the size of the Au nanoparticle used for catalysis is increased from 5 to 20 nm. Additional capping with a thin InP shell enhances the optical emission and does not affect the Fermi energy.(More)
We present a new light trapping technique to reduce reflection loss, as well as for light, focusing at submicron scales for solar cell and image sensing applications. We have fabricated hexagonal arrays of ZnO funnel-like structures on Si substrate by the patterned growth of ZnO nanowires in a hydrothermal growth process. The funnels are optimized so that(More)
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