Dr. Ajeet Kumar Profile

Dr. Ajeet Kumar

Assistant Professor at Delhi Technological Univ

SPIE Involvement:

Author

Area of Expertise:

large mode area fiber , fiber sensor , photonic crystal , high power fiber and waveguide laser , photonic crystal fiber , long period fiber and waveguide grating

Publications (19)

Proceedings Article | 20 August 2020 Poster + Paper

Supercontinuum generation in a hollow-core methanol-silica based photonic crystal fiber: computational model and analysis

Pooja Chauhan, Ajeet Kumar, Yogita Kalra

Proceedings Volume 11498, 114980T (2020) https://doi.org/10.1117/12.2568970

KEYWORDS: Supercontinuum generation, Dispersion, Photonic crystal fibers, Silica, Refractive index, Wavelength division multiplexing, Optical fibers

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Proceedings Article | 26 February 2020 Paper

Ultra-coherent supercontinuum generation in isopropanol-silica based photonic crystal fiber at 1300nm and 1600nm wavelengths

Pooja Chauhan, Ajeet Kumar, Yogita Kalra

Proceedings Volume 11289, 1128923 (2020) https://doi.org/10.1117/12.2544242

KEYWORDS: Supercontinuum generation, Dispersion, Photonic crystal fibers, Optical coherence tomography, Silica, Applied physics, Pulsed laser operation, Modulation, Cladding, Refractive index

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Proceedings Article | 9 September 2019 Paper

A multicomponent GAP-Se chalcogenide composition-based rectangular photonic crystal fiber for coherent supercontinuum generation

Pooja Chauhan, Ajeet Kumar, Yogita Kalra, Than Singh Saini

Proceedings Volume 11123, 1112310 (2019) https://doi.org/10.1117/12.2535677

KEYWORDS: Chalcogenides, Supercontinuum generation, Dispersion, Photonic crystal fibers, Refractive index, Cladding, Nonlinear optics, Mid-IR, Chalcogenide glass, Transparency

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Proceedings Article | 19 September 2018 Paper

Enhancement of Purcell factor in all-dielectric dimer

Reena Dalal, Yogita Kalra, Ajeet Kumar

Proceedings Volume 10720, 107200W (2018) https://doi.org/10.1117/12.2321041

KEYWORDS: Nanoparticles, Silicon, Dielectrics, Nanoantennas, Fiber optic communications, Fiber optics, Optical communications, Communication engineering, Magnetism

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Proceedings Article | 19 September 2018 Paper

Optical modeling and computational analysis of tapered dome shaped nanoantenna

Ayush Paliwal, Jorawar Singh Dham, Ajeet Kumar, Lakshay Gautam

Proceedings Volume 10722, 107222L (2018) https://doi.org/10.1117/12.2320890

KEYWORDS: Nanoantennas, Gold, Nanostructures, Domes, Optical spheres, Resonance enhancement, Plasmonics, Antennas, Nanoparticles, Silver

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Proceedings Article | 4 September 2018 Paper

Highly nonlinear spiral shaped photonic crystal fiber in a Ga-Sb-S chalcogenide glass for nonlinear applications

Pooja Chauhan, Ajeet Kumar, Yogita Kalra, Than Singh Saini

Proceedings Volume 10755, 1075510 (2018) https://doi.org/10.1117/12.2320901

KEYWORDS: Chalcogenide glass, Dispersion, Photonic crystal fibers, Antimony, Gallium, Mid-IR, Nonlinear optics, Supercontinuum generation, Nonlinear optical glasses, Nonlinear crystals

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Proceedings Article | 4 September 2018 Presentation + Paper

Design and analysis of graded rectangular-core photonic crystal fiber for terahertz communication

Lakshay Gautam, Alankrit Tomar, Ajeet Kumar

Proceedings Volume 10755, 1075508 (2018) https://doi.org/10.1117/12.2320912

KEYWORDS: Photonic crystal fibers, Terahertz radiation, Analytical research, Refractive index, Waveguides, Radio propagation, Cladding, Data communications, Wave propagation, Solids

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Proceedings Article | 28 August 2017 Presentation + Paper

All-dielectric cylindrical nanoantennas in the visible range

Reena Dalal, Nishant Shankhwar, Yogita Kalra, Ajeet Kumar, R. Sinha

Proceedings Volume 10344, 103440K (2017) https://doi.org/10.1117/12.2273718

KEYWORDS: Scattering, Nanoparticles, Magnetism, Dielectrics, Light scattering, Photovoltaics, Silicon, Light wave propagation, Optical properties, Optoelectronics

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Proceedings Article | 1 September 2015 Paper

Design and analysis of chevrons shaped split ring resonator in the mid-infrared region

N. Nandan, T. Saini, A. Kumar, R. Sinha

Proceedings Volume 9544, 95441D (2015) https://doi.org/10.1117/12.2188341

KEYWORDS: Surface plasmons, Split ring resonators, Terahertz radiation, Mid-IR, Reflectivity, Magnetism, Silicon, Refractive index, Gold, Metamaterials

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Proceedings Article | 26 August 2015 Paper

Design of single mode single polarization large mode area photonic crystal fiber

Kishor Naik, Than Singh Saini, Ajeet Kumar, Ravindra Sinha

Proceedings Volume 9586, 95860H (2015) https://doi.org/10.1117/12.2187902

KEYWORDS: Polarization, Photonic crystal fibers, Fiber optic communications, Telecommunications, Finite element methods, Birefringence, Cladding, Silica, Wave propagation, Optical communications

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Proceedings Article | 26 August 2015 Paper

Slow light generated via Brillouin scattering in small core chalcogenide photonic crystal fiber

A. Baili, R. Cherif, A. Ben Salem, A. Kumar, R. K. Sinha, M. Zghal

Proceedings Volume 9586, 95860P (2015) https://doi.org/10.1117/12.2188418

KEYWORDS: Acoustics, Slow light, Chalcogenides, Light scattering, Scattering, Photonic crystal fibers, Optical fibers, Optical communications, Single mode fibers, Refractive index

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Proceedings Article | 26 August 2015 Paper

Design and analysis of rectangular core photonic crystal fiber for supercontinuum generation

Than Singh Saini, Ajeet Kumar, Rim Cherif, R. Sinha, Mourad Zghal

Proceedings Volume 9586, 95860G (2015) https://doi.org/10.1117/12.2187884

KEYWORDS: Dispersion, Photonic crystal fibers, Supercontinuum generation, Mid-IR, Glasses, Femtosecond phenomena, Fiber optic communications, Optical communications, Communication engineering, Telecommunications

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SPIE Journal Paper | 7 July 2015

Design of small core tellurite photonic crystal fiber for slow-light-based application using stimulated Brillouin scattering

Rim Cherif, Amine Ben Salem, Than Singh Saini, Ajeet Kumar, Ravindra Sinha, Mourad Zghal

OE, Vol. 54, Issue 07, 075101, (July 2015) https://doi.org/10.1117/12.10.1117/1.OE.54.7.075101

KEYWORDS: Acoustics, Photonic crystal fibers, Slow light, Scattering, Scanning electron microscopy, Refractive index, Telecommunications, Electron microscopes, Glasses, Optical engineering

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Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crystal fibers (PCF) are rigorously studied. We propose a design of tellurite PCF that is used for slow-light-based applications. We developed a two-dimensional finite element mode solver to numerically study the acoustic and optical properties of complex refractive index profiles including tellurite PCF. Our results include the calculation of Brillouin gain spectrum, Brillouin gain coefficient (gB) and Brillouin frequency shift by taking into account the contribution of the higher-order acoustic modes. Several simulations were run by varying the air-filling ratio of various PCF structures to enhance the SBS. The real scanning electron microscope image of a small core of highly nonlinear tellurite fiber is considered. Optimized results show a frequency shift of 8.43 GHz and a Brillouin gain of 9.48×10−11 m/W with a time delay between 21 and 140 ns. Such fibers have drawn much interest because of their capacity for increasing and tailoring the SBS gain.

Proceedings Article | 5 September 2014

Design of equiangular spiral photonic crystal fiber for supercontinuum generation at 1550 nm

T. Saini, A. Baili, V. Dahiya, A. Kumar, R. Cherif, M. Zghal, R. Sinha

Proceedings Volume 9200, 920012 (2014) https://doi.org/10.1117/12.2061806

KEYWORDS: Dispersion, Photonic crystal fibers, Glasses, Supercontinuum generation, Raman scattering, Refractive index, Fiber optic communications, Optical communications, Communication engineering, Telecommunications

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An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has been presented. The structure parameters have been tailored for zero dispersion wavelength (ZDW) at λZDW=1570 nm. The fiber structure has high nonlinearity (γ = 2000 w^-1 Km^-1) at 1550 nm wavelength with very low and flat dispersion -0.152 [ps/(nm×km)]. We have generated supercontinuum using only 2 mm length of tellurite ES PCF with low input pulse energy of 200 pJ by pumping at 1550 nm. The proposed fiber may be a suitable candidate for nonlinear applications.

Proceedings Article | 5 September 2014

Design and analysis of large-mode-area microstructured polymer optical fibre with single-mode operation

T. Saini, V. Dahiya, A. Kumar, R. Sinha

Proceedings Volume 9200, 92000H (2014) https://doi.org/10.1117/12.2061825

KEYWORDS: Polymer optical fibers, Polymers, Finite element methods, Optical fibers, Cladding, Structured optical fibers, Polymethylmethacrylate, Silica, Fiber lasers, Optical amplifiers

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A single mode microstructured polymer optical fiber has been designed and analysed based on finite element method (FEM). The design parameters of proposed microstructured polymer optical fiber structure have been optimized to obtain single mode operation along with mode area of 895 μm². The differential loss between fundamental and higher order modes of structure have been obtained very large (~10³) with negligible loss of fundamental mode. The proposed structure is effectively single mode at 632.8 nm wavelength after the short distance 1.65 m with very low loss of guiding mode. The proposed structure is applicable for high power delivery devices.

Proceedings Article | 5 September 2014

2-10 µm supercontinuum broadening using a highly nonlinear chalcogenide microfiber for mid-IR applications

A. Baili, R. Cherif, T. Saini, A. Kumar, R. Sinha, M. Zghal

Proceedings Volume 9200, 92000S (2014) https://doi.org/10.1117/12.2061848

KEYWORDS: Dispersion, Mid-IR, Chalcogenides, Supercontinuum generation, Nonlinear optics, Femtosecond phenomena, Infrared spectroscopy, Waveguides, Wave propagation, Fiber lasers

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A new design of the As2Se3 microfiber has been presented. With the optimized geometric parameters: pitch Λ= 0.8 μm and five different air filling ratios varying from 0.4 to 0.95, the structure exhibits an all normal dispersion with a flat top equal to -2.3 [ps/(nm.km)], a confinement loss less than 10^-2 dB/km, and a large nonlinear coefficient equal to 7250 (w. km)^-1. Using the generalized nonlinear Schrödinger equation, we generate a very broadband supercontinuum (SC) in the mid-infrared region. By pumping the fiber at λp=5.24 μm with a femtosecond laser having 50 fs as a width with a relatively low energy of E=80 pJ, we generate a large spectrum extending from 2 μm to 10 μm in only 2 mm fiber length. The generated SC demonstrates perfect coherence property over the entire bandwidth. SC generation extended into the mid-infrared (IR) spectral region have potential usefulness in a variety of applications requiring a broad mid-IR spectrum such as fiber sensing, IR spectroscopy, fiber laser, optical tomography coherence.

Proceedings Article | 28 August 2014

Design of single-polarization single-mode photonic nanowire

A. Baili, R. Cherif, A. Ben Salem, T. S. Saini, A. Kumar, R. Sinha, M. Zghal

Proceedings Volume 9170, 917014 (2014) https://doi.org/10.1117/12.2061887

KEYWORDS: Dispersion, Cladding, Polarization, Birefringence, Fiber optic gyroscopes, Fiber optics sensors, Silica, Nanowires, Photonic nanostructures, Photon polarization

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A novel design of single polarization single mode (SPSM) photonic nanowire is proposed. Using a cladding structure with circular air holes, a new design of a photonic nanowire with ultra-wideband range of 740 nm for SPSM operation is obtained. The numerical results show that the SPSM-nanowire is low-loss within the wavelengths ranging from 1.17 μm to 1.91 μm, the confinement loss of the slow-axis mode is less than 0.15 dB/km and the fast-axis mode is unguided. This fiber has greater advantages in polarization sensitive applications, such as fiber optic gyroscopes, fiber optic current sensors, high-power fiber lasers, and coherent optical communications.

Proceedings Article | 25 September 2013

Large-core single-mode trench assisted leaky channel waveguide for high-power applications

Vinita Dahiya, Than Saini, Ajeet Kumar, Vipul Rastogi, Ravindra Sinha

Proceedings Volume 8847, 88471P (2013) https://doi.org/10.1117/12.2023466

KEYWORDS: Waveguides, Channel waveguides, Cladding, Waveguide lasers, Refractive index, Wave propagation, High power lasers, Waveguide modes, Integrated optics, Optical communications

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We present a multi-trench channel waveguide design that supports a single-guided mode with large-mode area. Geometrically shaped waveguide with suitable design parameters ensure effective single-mode operation by introducing high leakage loss to higher-order modes while a nominal loss to the fundamental mode. A waveguide of ~ 2.2 mm length is able to ensure single-mode operation with the core area of 100 μm². Such a large confinement area for mode propagation can effectively suppress nonlinear optical effects. The proposed channel waveguide structure is expected to find applications in high power devices and components such as high power waveguide lasers, amplifiers and sensors.

Proceedings Article | 25 September 2013

Selectively filled large-mode-area photonic crystal fiber for high power applications

Than Saini, Ajeet Kumar, Vipul Rastogi, Ravindra Sinha

Proceedings Volume 8847, 88471Q (2013) https://doi.org/10.1117/12.2023472

KEYWORDS: Photonic crystal fibers, Refractive index, Cladding, Finite element methods, Photonic crystals, Surgery, Silica, High power fiber lasers, Sensors, Crystals

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A large-mode-area (LMA) single-mode (SM) photonic crystal fiber (PCF) structure for applications in high power fiber lasers, amplifiers and sensors is proposed. In the proposed structure the center air hole has been removed to form the core and the six elliptical air holes of inner ring around the center core have been selectively filled with high refractive index material. Effects of design parameters on SM operation and mode area are numerically investigated by using the full vectorial finite-element method. Structure offers large-mode-area exceeding 835 μm² at 1.064 μm wavelength. A PCF with such a large-mode-area would significantly reduce the nonlinear effects and would be useful for high power applications.

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