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47 results on '"Choudhary Saumya"'

1. Phase-matched third-harmonic generation in silicon nitride waveguides

Author

Vijayakumar Surendar, Vyas Kaustubh, Espinosa Daniel H. G., Reshef Orad, Song Meiting, Awan Kashif Masud, Choudhary Saumya, Cardenas Jaime, Boyd Robert W., and Dolgaleva Ksenia

Subjects
harmonic generation, waveguide, frequency conversion, silicon nitride, nonlinear optics, Physics, QC1-999
Abstract

Third-harmonic generation (THG) in silicon nitride waveguides is an ideal source of coherent visible light, suited for ultrafast pulse characterization, telecom signal monitoring and self-referenced comb generation due to its relatively large nonlinear susceptibility and CMOS compatibility. We demonstrate third-harmonic generation in silicon nitride waveguides where a fundamental transverse mode at 1,596 nm is phase-matched to a TM02 mode at 532 nm, confirmed by the far-field image. We experimentally measure the waveguide width-dependent phase-matched wavelength with a peak-power-normalized conversion efficiency of 5.78 × 10−7 %/W2 over a 660-μm-long interaction length.

Published
2024
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2. Stimulated emission tomography for efficient characterization of spatial entanglement

Author

Xu, Yang, Choudhary, Saumya, and Boyd, Robert W.

Subjects
Quantum Physics, Physics - Optics
Abstract

Stimulated emission tomography (SET) is an excellent tool for characterizing the process of spontaneous parametric down-conversion (SPDC), which is commonly used to create pairs of entangled photons for use in quantum information protocols. The use of stimulated emission increases the average number of detected photons by several orders of magnitude compared to the spontaneous process. In a SET measurement, the parametric down-conversion is seeded by an intense signal field prepared with specified mode properties rather than by broadband multi-modal vacuum fluctuations, as is the case for the spontaneous process. The SET process generates an intense idler field in a mode that is the complex conjugate to the signal mode. In this work we use SET to estimate the joint spatial mode distribution (JSMD) in the Laguerre-Gaussian (LG) basis of the two photons of an entangled photon pair. The pair is produced by parametric down-conversion in a beta barium borate (BBO) crystal with type-II phase matching pumped at a wavelength of 405 nm along with a 780-nm seed signal beam prepared in a variety of LG modes to generate an 842-nm idler beam of which the spatial mode distribution is measured. We observe strong idler production and good agreement with the theoretical prediction of its spatial mode distribution. Our experimental procedure should enable the efficient determination of the photon-pair wavefunctions produced by low-brightness SPDC sources and the characterization of high-dimensional entangled-photon pairs.

Published
2024

3. Controlling nonlinear rogue wave formation using the coherence length of phase noise

Author

Choudhary, Saumya, Black, A. Nicholas, Antikainen, Aku, and Boyd, Robert W.

Subjects
Physics - Optics, Nonlinear Sciences - Pattern Formation and Solitons
Abstract

Weak phase noise present on an optical field can be amplified by a self-focusing nonlinearity and form intense "rogue wave" features. Here, we study the effect of the coherence length (or grain size) of this phase noise on the likelihood of rogue wave formation in the presence of a self-focusing nonlinearity. We show that while the likelihood of rogue wave formation increases with laser power when the coherence length is only slightly smaller that the beam diameter, the likelihood is minimally affected by change in laser power when the coherence length is significantly smaller than the beam diameter. Our study provides insight into the interaction of nonlinearity with phase instabilities on a field, and could be useful in applications such as reducing the effect of turbulence-induced breakup of intense laser beams, and developing radiance limiters to reduce the focusable power in a beam.

Published
2022

4. Suppression of Nonlinear Optical Rogue Wave Formation Using Polarization-Structured Beams

Author

Black, A. Nicholas, Choudhary, Saumya, Arroyo-Rivera, E. Samuel, Woodworth, Hayden, and Boyd, Robert W.

Subjects
Physics - Optics
Abstract

A nonlinear self-focusing material can amplify random small-amplitude phase modulations present in an optical beam, leading to the formation of amplitude singularities commonly referred to as optical caustics. By imposing polarization structuring on the beam, we demonstrate the suppression of amplitude singularities caused by nonlinear self-phase modulation. Our results are the first to indicate that polarization-structured beams can suppress nonlinear caustic formation in a saturable self-focusing medium and add to the growing understanding of catastrophic self-focusing effects in beams containing polarization structure., Comment: 6 pages, 3 figures

Published
2022
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6. Measurement of the radial mode spectrum of photons through a phase-retrieval method

Author

Choudhary, Saumya, Sampson, Rachel, Miyamoto, Yoko, Magana-Loaiza, Omar S., Rafsanjani, Seyed Mohammad Hashemi, Mirhosseini, Mohammad, and Boyd, Robert W.

Subjects
Physics - Optics
Abstract

We propose and demonstrate a simple and easy-to-implement projective-measurement protocol to determine the radial index 'p' of a Laguerre-Gaussian (LGlp) mode. Our method entails converting any specified high-order LG0p mode into a near-Gaussian distribution that matches the fundamental mode of a single-mode fiber (SMF) through the use of two phase-screens (unitary transformations) obtained by applying a phase-retrieval algorithm. The unitary transformations preserve the orthogonality of modes and guarantee that our protocol can, in principle, be free of crosstalk. We measure the coupling efficiency of the transformed radial modes to the SMF for different pairs of phase-screens. Because of the universality of phase-retrieval methods, we believe that our protocol provides an efficient way of fully characterizing the radial spatial profile of an optical field.

Published
2018
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8. Immunomodulatory Effect of Phytoactive Compounds on Human Health: A Narrative Review Integrated with Bioinformatics Approach

Author

Choudhary, Saumya, primary, Khan, Sheeba, additional, Rustagi, Shivani, additional, Rajpal, Vijay Rani, additional, Khan, Noor Saba, additional, Kumar, Neeraj, additional, Thomas, George, additional, Pandey, Anamika, additional, Hamurcu, Mehmet, additional, Gezgin, Sait, additional, Zargar, Sajad Majeed, additional, and Khan, Mohd Kamran, additional

Published
2024
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22. Photon Acceleration Using a Time-Varying Epsilon-near-Zero Metasurface

Author

Liu, Cong, primary, Alam, M. Zahirul, additional, Pang, Kai, additional, Manukyan, Karapet, additional, Reshef, Orad, additional, Zhou, Yiyu, additional, Choudhary, Saumya, additional, Patrow, Joel, additional, Pennathurs, Anuj, additional, Song, Hao, additional, Zhao, Zhe, additional, Zhang, Runzhou, additional, Alishahi, Fatemeh, additional, Fallahpour, Ahmad, additional, Cao, Yinwen, additional, Almaiman, Ahmed, additional, Dawlaty, Jahan M., additional, Tur, Moshe, additional, Boyd, Robert W., additional, and Willner, Alan E., additional

Published
2021
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30. Weak superradiance in arrays of plasmonic nanoantennas

Author

Choudhary, Saumya, primary, De Leon, Israel, additional, Swiecicki, Sylvia, additional, Awan, Kashif Masud, additional, Schulz, Sebastian A., additional, Upham, Jeremy, additional, Alam, M. Zahirul, additional, Sipe, J. E., additional, and Boyd, Robert W., additional

Published
2019
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35. Ethics in Publishing: An Opinion on its Importance

Author

Khan, Mohd. Kamran ,, primary, Anamika, Anamika, additional, Choudhary, Saumya, additional, Gulcan, Kamer, additional, Khan, Sheeba, additional, Rustagi, Shivani, additional, Thomas, George, additional, Hamurcu, Mehmet, additional, Gezgin, Sait, additional, and Hakki, Erdogan E., additional

Published
2018
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37. On Plasmonic Superradiance, the Scaling Laws of Spontaneous Parametric Downconversion, and the Principles and Recent Advances in Nonlinear Optics

Author

Choudhary, Saumya

Subjects
Type-I phase-matching, Superradiance, Particle plasmon resonances, Bi-photon rate, Physics::Optics, Nanoantenna arrays, Spontaneous parametric downconversion
Abstract

This thesis covers three different topics. The first part is a pedagogical review of the basic principles and recent advances in nonlinear optics. It was originally written as a chapter for the proceedings of the “International School of Physics (Enrico Fermi)” summer school on Photonics held in June, 2014. It is included to provide some background information about nonlinear optical processes in general, and is particularly relevant for the third part of this thesis which is based on the second-order nonlinear optical process of spontaneous parametric downconversion. The second part is based on original research, and deals with superradiance in plasmonic nanostructures. The process of superradiance, as introduced by Dicke in 1954, entails the shortening of the spontaneous emission lifetime of a collection of N quantum emitters as a consequence of the development of a macroscopic dipole moment. Specifically, the lifetime is shortened by a factor of 1/N, and the linewidth is broadened by a factor of N. Such a linewidth dependence has been previously observed in systems of several plasmonic ‘emitters’. However, a clear physical insight into this phenomenon and how it relates to Dicke superradiance has not been shown yet. In this part, we demonstrate by experiment, simulation, and a simple analytical model that Dicke’s superradiance can indeed be observed in a planar array of plasmonic nanoantennas, with a linewidth that scales linearly with the number of nanoantennas within a square wavelength. The third part is also based on original research, and is based on the scal- ing laws of spontaneous parametric downconversion (SPDC) for a type-I phase- matching configuration. The variation of bi-photon generation rate, heralding efficiency and radiance with parameters such as crystal length, pump focussing and collection waist sizes are examined for collinear and non-collinear emission. The results can be used to maximize the brightness of the SPDC source or increase the heralding efficiency depending on the application.

Published
2016
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42. Hydroxypropyl Methylcellulose and Whey Protein Concentrate as Technological Improver in Formulation of Gluten-Free Protein Rich Bread.

Author

RUSTAGI, SHIVANI, KHAN, SHEEBA, CHOUDHARY, SAUMYA, PANDEY, ANAMIKA, KHAN, MOHD. KAMRAN, KUMARI, ANU, and SINGH, AVINASH

Subjects
WHEY protein concentrates, METHYLCELLULOSE, GLUTEN-free foods, BREAD quality, NUTRITIONAL value of bread
Abstract

Wheat breads contains gluten protein that is responsible for the viscoelastic properties of dough. There has recently been an increase in the prevalence of gluten-related disorders including celiac disease and non-celiac gluten sensitivity. Therefore, this study has been designed for improving bread production for gluten-free bread (sorghum and potato starch) using hydroxypropyl methylcellulose (HPMC) and whey protein concentrate (WPC-70) as technological improver and optimizing it using response surface methodology (RSM). RSM was used to investigate the influence of predictor variables (HPMC and WPC-70) on bread quality in terms of crust and crumb texture and color, flavor, porosity and overall acceptability. The HPMC level varies from 2- 3% and WPC-70 from 12-15%. Quadratic models are developed to fit with experimental data. The predictor variables had desirable effect on all the responses. Finally, 3% HPMC and 15 % WPC-70 were chosen as optimum levels. The obtained gluten-free bread can be considered as protein rich. The optimized bread was analyzed for various parameters including protein, moisture, fat, crude fiber content, acid insoluble ash and pH.The analyzed results were reported as 10.48g, 38.73g, 8.97g, 2.8g, 0.134g, 6.1 respectively. The microbiological analysis of optimized bread was performed. The total plate count was <10, yeast & mould was <10 andcoliform count Nil. Hence, it can be stated that HPMC and WPC-70 can be efficiently used to obtain gluten-free protein rich bread. [ABSTRACT FROM AUTHOR]

Published
2018
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