Pratyasha Sahani

• Postdoctoral researcher
• Tohoku University

We fabricate a device that configures the tunable air gap Fabry‒Pérot filter with a static gradient thickness filter to estimate air gap dimension in tunable filter. The chip-level microelectromechanical integration of gradient thickness filter can serve the purpose of device miniaturization while performing air gap sensing in visible wavelength ra...

We fabricate a microelectromechanical systems (MEMS)-based device configuring the tunable air gap Fabry–Pérot filter (FPF) with a static gradient thickness filter on the same platform. The proposed double filter configuration offers a wavelength calibration approach that accurately estimates the air gap dimension in the tunable air gap FPF. The wav...

A miniature low-cost pixelated gradient thickness optical filter is proposed to achieve spectroscopy in the visible wavelength range. The optical filter consists of a two-dimensional array of metal-dielectric-metal thin films arranged in Fabry–Pérot filter configurations with discretely varying cavity thicknesses. The wavelength-selective character...

A single monolayer photonic crystal (PhC) of polystyrene(PS) colloidal particles with gold nanoparticles drop-casted on the surface have been employed as templates for the detection of dye molecules (methylene blue is taken as analyte for the case study) at very low concentrations using the surface-enhanced Raman scattering (SERS) technique. Result...

We propose a pixelized gradient thickness color filter as the compact and space-saving element for achieving simultaneous imaging and spectroscopy using a single image sensor. By replacing the RGB filter integrated in portable devices this can serve the novel purpose on the same platform, and hence makes the device versatile.

We have computed the internal electric field distribution in monolayer, bilayer, and trilayer colloidal photonic crystal thin films on a glass substrate. The field distributions are evaluated on the top photonic crystal layer under the effects of additional layers along the direction of light propagation We have also investigated the field distribu...

The response of an artificial opal to different polarization states of incident light is quantitatively analyzed by performing Mueller matrix (MM) polarimetry measurements in the transmission geometry. In addition, the wavelength-resolved polarization effects of the transmitted light from the opal are quantitatively investigated especially for the...

The interaction of linearly polarized light with self-assembled photonic crystals (opals) grown from polymeric colloids is studied. The experimental work is carried out on opals with and without dye molecules. These active and passive opals influence the polarization state of transmitted light very differently and the role of photonic stop band is...

We study a 2D photonic crystal slab for its properties of polarizing light propagating in the plane of periodicity and for light incident from outside the plane of the slab as well. We identify the frequency ranges that can yield polarized light for both cases. The analysis is done for triangular and square lattice configurations in both symmetric...