Govind Kumar

Followers

Following

Public Views

Related Authors

GOVIND KUMAR

Alexandre Tishchenko

Thomas Kämpfe

Universite Jean Monnet - Saint-Etienne

Govind Kumar

Matthew Grein

MIT Lincoln Laboratory

Yeonsang Park

M. Skolnick

J. Schilling

Martin Luther University Halle-Wittenberg

P. Viktorovitch

Nicolas Passarelli

Interests

Uploads

Papers by Govind Kumar

Supplementary document for Reconstructive Spectrometer using Photonic Crystal Cavity - 5363962.pdf

Supplement Document 1 contains Figs. S1-S7, Tables S1-S2, and discussion

DownloadEdit

Translationally Invariant Generation of Annular Beams Using Thin Films

IEEE Photonics Technology Letters, 2020

Thin film optical elements exhibiting translational invariance, and thus robustness to optical mi... more Thin film optical elements exhibiting translational invariance, and thus robustness to optical misalignment, are crucial for rapid development of compact and integrated optical devices. In this letter, we experimentally demonstrate a beam-shaping element that generates an annular beam by spatially filtering the fundamental Gaussian mode of a laser beam. The element comprises of a one-dimensional photonic crystal cavity fabricated using sputtered thin films. The planar architecture and in-plane symmetry of the element render our beam-shaping technique translationally invariant. The generated annular beam is sensitive to the polarization direction and the wavelength of the incident laser beam. Using this property of the annular beam, we show simultaneous generation of concentric annular beams of different wavelengths. Our experimental observations show an excellent agreement with simulation results performed using finite-difference time-domain method. Such a beam-shaping element has applications in areas ranging from microscopy and medicine to semiconductor lithography and manufacturing in microelectronics industry.

DownloadEdit

Generation of Annular Beam using Photonic Crystal Cavity

Conference on Lasers and Electro-Optics, 2020

We demonstrate generation of an annular beam by spatially filtering a circularly-polarized Gaussi... more We demonstrate generation of an annular beam by spatially filtering a circularly-polarized Gaussian beam using a photonic crystal cavity that exhibits in-plane symmetry and narrow bandpassfiltering. Our experimental results match well with simulations.

Edit

Reconstructive spectrometer using a photonic crystal cavity

Optics Express, 2021

Optical spectrometers have propelled scientific and technological advancements in a wide range of... more Optical spectrometers have propelled scientific and technological advancements in a wide range of fields. While sophisticated systems with excellent performance metrics are serving well in controlled laboratory environments, many applications require systems that are portable, economical, and robust to optical misalignment. Here, we propose and demonstrate a spectrometer that uses a planar one-dimensional photonic crystal cavity as a dispersive element and a reconstructive computational algorithm to extract spectral information from spatial patterns. The simple fabrication and planar architecture of the photonic crystal cavity render our spectrometry platform economical and robust to optical misalignment. The reconstructive algorithm allows miniaturization and portability. The intensity transmitted by the photonic crystal cavity has a wavelength-dependent spatial profile. We generate the spatial transmittance function of the system using finite-difference time-domain method and also...

DownloadEdit

Status of Plasmodium Falciparum and Vivax in Jharkhand: A Five Year (2004-08) Retrospective Study at Rajendra Institute of Medical Sciences, Ranchi

Malaria is well known for its fatalities worldwide. In India, it is still endemic in many areas w... more Malaria is well known for its fatalities worldwide. In India, it is still endemic in many areas where two species of Plasmodium namely Plasmodium vivax and Plasmodium falciparum are reported. P.vivax is widespread, creating lots of morbidities across the country. P. falciparum, on the other hand, though comparatively narrow in its infectious volume, is a serious cause of mortalities in India. A five year survey was conducted from 2004 to 2008 in a high malaria-hit district, Ranchi. Thick and thin blood smears were made at the Department of Clinical Pathology, Rajendra Institute of Medical Sciences (RIMS), where the microscopic examinations were carried out. The overall reported and examined cases at RIMS included 36643 suspected malaria cases, out of which, 21833(59.5%) were found positive. Out of these positive cases, 6842(31.3%) were confirmed as P. falciparum patients and 14991(68.6%) as P. vivax cases respectively. Number of negative cases was 14811 (40.4%). In this study, it wa...

Edit

Govind Kumar

Uploads

Papers by Govind Kumar

Log In