Ravindra Sinha - Academia.edu (original) (raw)
Papers by Ravindra Sinha
Progress in Quantum Electronics, Aug 1, 2021
Abstract Mid-infrared region (2–20 μm) is an important region of electromagnetic spectrum. Most ... more Abstract Mid-infrared region (2–20 μm) is an important region of electromagnetic spectrum. Most of the molecules including CH4, CO, NO, NO2, C6H6, TNT, NH3, SF6, HNO3, greenhouse gas radiation etc. have their fundamental vibrations in this domain. Thus, the mid-infrared region is known as ‘molecular fingerprint region’ and desirable to get the signature of these molecules. Tellurite and chalcogenide glasses have the advantages of a wide transparency window (up to ~20 μm) and very high optical nonlinearities, making them decent candidates for the mid-infrared supercontinuum generation. Photonic crystal fibers provide the wavelength-scale periodic arrangement of microstructure along their length. The core of the photonic crystal fibers and two-dimensional photonic crystal based on diverse geometries and the materials, permitting supercontinuum generation due to various nonlinear effects in an enormously broad spectral range. In this review paper, we report the recent developments in the field of mid-infrared supercontinuum generation in both the tellurite and chalcogenide glass state-of-the-art optical fibers. Particular attention is paid to the mid-infrared supercontinuum generation in the step-index, suspended-core, tapered, and photonic crystal fibers or microstructured optical fibers in tellurite and chalcogenide glasses. The coherence property of mid-infrared supercontinuum generation in all-normal dispersion engineered specialty optical fibers is also reviewed.
Optics Express, 2021
Metal nanomaterials have been widely used to generate photoacoustic (PA) signals because of their... more Metal nanomaterials have been widely used to generate photoacoustic (PA) signals because of their high optical absorption characteristics. However, the PA conversion efficiency of metal nanomaterials is limited by the single-wavelength absorption at the resonant peak. To mitigate this issue, a three-layer ultrathin film containing a thin PDMS layer sandwiched between two ultrathin chromium films is proposed. This kind of film structure can attain high optical absorbance (>80%) through the visible light range (450-850 nm). The optical absorption characteristics can be easily modulated by varying the thickness of the PDMS layer. Under the same excitation condition, the PA signal generated by this film structure is twice that of an only Cr film and three times that of an only Au film. This film structure is easily fabricated and can operate with lasers having different central wavelengths or even white light sources, leading to its applications in many fields, including photoacoustic communications and audio transducers.
Journal of Lightwave Technology, 2015
Journal of Lightwave Technology, 2015
RSC Adv., 2015
A one-step electrochemical route for the synthesis, functionalization and deposition of Au nanost... more A one-step electrochemical route for the synthesis, functionalization and deposition of Au nanostructures and for the bi-enzyme functionalization of a Au electrode has been proposed.
Optical and Quantum Electronics, 1984
1. Introduction Highly elliptical core fibres are used as single polarization single mode (SPSM) ... more 1. Introduction Highly elliptical core fibres are used as single polarization single mode (SPSM) fibres. These fibres have a large number of applications such as in coherent optical communication systems [ 1 ], fibre optic sensors [2] and in coupling with polarization-sensitive integrated ...
Journal of Lightwave Technology, 2009
2009 International Conference on Emerging Trends in Electronic and Photonic Devices & Systems
ABSTRACT
2009 International Conference on Emerging Trends in Electronic and Photonic Devices & Systems
Slow light transmission with high delay bandwidth product of the order of 87.41 in a large bandwi... more Slow light transmission with high delay bandwidth product of the order of 87.41 in a large bandwidth of 4.4 THz below silica light line is achieved in the proposed SOI based photonic crystal waveguide with hexagonal arrangement of elliptical air holes. This Delay bandwidth product indicates its buffering capacity. Within this bandwidth, group velocity dispersion is evaluated on the order
Journal of Microwaves and Optoelectronics, May 1, 2004
In this paper, coupling characteristics of photonic crystal (PhC) directional couplers are obtain... more In this paper, coupling characteristics of photonic crystal (PhC) directional couplers are obtained using the finite difference time domain (FDTD) method. The two photonic crystal waveguides are used to design the photonic crystal directional coupler. It is shown that coupling characteristics of PhC directional couplers are polarization dependent. Coupling coefficient and coupling length of PhC directional couplers for both transverse electric (TE) and transverse magnetic (TM) modes are obtained. It is observed that the coupling length of the proposed PhC directional couplers falls in the micrometer range as compared to that of conventional optical waveguide directional couplers whose coupling length falls in the millimeter range.
Progress in Quantum Electronics, Aug 1, 2021
Abstract Mid-infrared region (2–20 μm) is an important region of electromagnetic spectrum. Most ... more Abstract Mid-infrared region (2–20 μm) is an important region of electromagnetic spectrum. Most of the molecules including CH4, CO, NO, NO2, C6H6, TNT, NH3, SF6, HNO3, greenhouse gas radiation etc. have their fundamental vibrations in this domain. Thus, the mid-infrared region is known as ‘molecular fingerprint region’ and desirable to get the signature of these molecules. Tellurite and chalcogenide glasses have the advantages of a wide transparency window (up to ~20 μm) and very high optical nonlinearities, making them decent candidates for the mid-infrared supercontinuum generation. Photonic crystal fibers provide the wavelength-scale periodic arrangement of microstructure along their length. The core of the photonic crystal fibers and two-dimensional photonic crystal based on diverse geometries and the materials, permitting supercontinuum generation due to various nonlinear effects in an enormously broad spectral range. In this review paper, we report the recent developments in the field of mid-infrared supercontinuum generation in both the tellurite and chalcogenide glass state-of-the-art optical fibers. Particular attention is paid to the mid-infrared supercontinuum generation in the step-index, suspended-core, tapered, and photonic crystal fibers or microstructured optical fibers in tellurite and chalcogenide glasses. The coherence property of mid-infrared supercontinuum generation in all-normal dispersion engineered specialty optical fibers is also reviewed.
Optics Express, 2021
Metal nanomaterials have been widely used to generate photoacoustic (PA) signals because of their... more Metal nanomaterials have been widely used to generate photoacoustic (PA) signals because of their high optical absorption characteristics. However, the PA conversion efficiency of metal nanomaterials is limited by the single-wavelength absorption at the resonant peak. To mitigate this issue, a three-layer ultrathin film containing a thin PDMS layer sandwiched between two ultrathin chromium films is proposed. This kind of film structure can attain high optical absorbance (>80%) through the visible light range (450-850 nm). The optical absorption characteristics can be easily modulated by varying the thickness of the PDMS layer. Under the same excitation condition, the PA signal generated by this film structure is twice that of an only Cr film and three times that of an only Au film. This film structure is easily fabricated and can operate with lasers having different central wavelengths or even white light sources, leading to its applications in many fields, including photoacoustic communications and audio transducers.
Journal of Lightwave Technology, 2015
Journal of Lightwave Technology, 2015
RSC Adv., 2015
A one-step electrochemical route for the synthesis, functionalization and deposition of Au nanost... more A one-step electrochemical route for the synthesis, functionalization and deposition of Au nanostructures and for the bi-enzyme functionalization of a Au electrode has been proposed.
Optical and Quantum Electronics, 1984
1. Introduction Highly elliptical core fibres are used as single polarization single mode (SPSM) ... more 1. Introduction Highly elliptical core fibres are used as single polarization single mode (SPSM) fibres. These fibres have a large number of applications such as in coherent optical communication systems [ 1 ], fibre optic sensors [2] and in coupling with polarization-sensitive integrated ...
Journal of Lightwave Technology, 2009
2009 International Conference on Emerging Trends in Electronic and Photonic Devices & Systems
ABSTRACT
2009 International Conference on Emerging Trends in Electronic and Photonic Devices & Systems
Slow light transmission with high delay bandwidth product of the order of 87.41 in a large bandwi... more Slow light transmission with high delay bandwidth product of the order of 87.41 in a large bandwidth of 4.4 THz below silica light line is achieved in the proposed SOI based photonic crystal waveguide with hexagonal arrangement of elliptical air holes. This Delay bandwidth product indicates its buffering capacity. Within this bandwidth, group velocity dispersion is evaluated on the order
Journal of Microwaves and Optoelectronics, May 1, 2004
In this paper, coupling characteristics of photonic crystal (PhC) directional couplers are obtain... more In this paper, coupling characteristics of photonic crystal (PhC) directional couplers are obtained using the finite difference time domain (FDTD) method. The two photonic crystal waveguides are used to design the photonic crystal directional coupler. It is shown that coupling characteristics of PhC directional couplers are polarization dependent. Coupling coefficient and coupling length of PhC directional couplers for both transverse electric (TE) and transverse magnetic (TM) modes are obtained. It is observed that the coupling length of the proposed PhC directional couplers falls in the micrometer range as compared to that of conventional optical waveguide directional couplers whose coupling length falls in the millimeter range.