We propose a novel SOI rib horizontal slot waveguide geometry to achieve larger than 10% enhancem... more We propose a novel SOI rib horizontal slot waveguide geometry to achieve larger than 10% enhancement in evanescent field vis-a-vis a conventional horizontal slot waveguide and hence yielding higher sensitivity in its environment sensing applications.
Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XI, 2018
We have numerically demonstrated refractive index sensing using terahertz metamaterials comprised... more We have numerically demonstrated refractive index sensing using terahertz metamaterials comprised of single split gap resonators. Sensing capabilities of odd and even order resonance modes are precisely investigated. In this scheme the top surface of metamaterials array is covered with a thin layer of polyimide whose refractive could be changed manually. The sensitivity and corresponding figure of merit (FoM) of several lowest order modes are examined with respect to the different thicknesses of the coated polyimide film. We have investigated the electric field distributions at different resonances for the MMs. Although we have mainly focused on refractive index sensing but this study could be extremely useful for the development of metamaterials based sensing devices, bio-sensors etc.
Co-existence and interplay between mesoscopic light dynamics with singular optics in spatially di... more Co-existence and interplay between mesoscopic light dynamics with singular optics in spatially disordered waveguide lattices is reported. Disorder induced singular behavior and diffusive wave propagation are quantitatively analyzed.
International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '96, 1998
Low-loss high-silica fibers were first reported in 1970 and since then these glass fibers have pr... more Low-loss high-silica fibers were first reported in 1970 and since then these glass fibers have proven to be the most viable transmission media for lightwave communication. Even though the first low loss fiber was a single-mode fiber, initial systems revolved around multimode fibers from the point of view of practical reasons like easier fiber to fiber splicing and coupling from off-the-shelf available LEDs. Since early 1980s, single-mode fibers became the preferred media for optical transmission and single-mode fibers overtook the multimode fibers for lightwave communication. Networks which operate with single-mode fibers at the 1.31 /mm low-loss wavelength window are now taken for granted. Operations with advanced fiber designs at the silica fiber’s lowest loss window of 1.55 /mm are now gearing to take over the long-haul routes; these are contemplated to be based on erbium doped fiber amplifiers (EDFA) and dispersion shifted fibers. An alternative and promising scheme for this wavelength window involving use of already laid fibers optimized for 1.31 /an requires insertion of a dispersion compensating fiber(DCF) as an additional component in the link. In the immediate future, lightwave systems would operate with EDFA at the OC-48 level, which amounts to a bit rate of — 2.5 Gb/s and are compatible with SDH (STM-16) networks. For WDM transmission with EDFAs, one would require a variety of in-line fiber components like wavelength selective couplers, and bandpass/bandstop filters to add/drop channels. Until recently, optical fibers were considered to be optically linear. However, with the introduction of EDFAs, which provide large and broadband (* 30-35 nm) optical gains, a large number of WDM information channels can be transmitted and simultaneously provided gains across this broad gain spectrum of EDFAs. Furthermore, amplifier spacings could be much longer than the present day regenerator spacings. These two fall outs of EDFA namely, large optical power density and long interaction lengths have elevated optical fiber nonlinearities to an important design issue in lightwave systems. In this presentation we would aim to trace the evolutionary trends in lightwave communications seen along the above lines since the reporting of the first low-loss fibers a quarter century ago. INTRODUCTION
2012 5th International Conference on Computers and Devices for Communication (CODEC), 2012
The huge progress already seen in optical fiber communication by the late 1990s led one to questi... more The huge progress already seen in optical fiber communication by the late 1990s led one to question `Is there any scope for further research in optical fibers?' The answer however turned out to be `indeed yes'. There emerged a resurgence of interest to design and fabricate exotic class of specialty fibers, in which transmission losses of the material would not be a limiting factor while nonlinearity and dispersion characteristics could be conveniently tailored. Research targeted towards such fiber designs led to the emergence of a new class of fibers, broadly referred to as microstructured optical fibers, which are characterized by wavelength-scale refractive index features across its physical cross-section resulting in photonic bandgaps when appropriately designed. This talk would focus on our research in recent years on designs of a variety of such photonic bandgap fibers for a variety of applications such as dispersion compensating fibers, metro fibers, supercontinuum (SC) light generating fibers, parabolic pulse generating fibers for fiber lasers, almost non-dispersive propagation of ultra-short light pulses for biomedical applications, large mode area soft-glass based fibers for mid-infrared wavelengths, and chalcogenide fiber-based mid-ir fibers as light source, SC generator, and for high power delivery.
This chapter describes the history, underlying physics, modeling of propagation characteristics, ... more This chapter describes the history, underlying physics, modeling of propagation characteristics, design issues, and fabrication of 1D photonic bandgap-guided bragg fibers (PBGF). It has indeed emerged as a specialty fiber with the potential for several attractive applications. In a conventional optical fiber, light is guided by total internal reflection because of the refractive index contrast that exists between a finite-sized cylindrical core and the cladding of lower refractive index that surrounds it. Whereas, in a PBGF, light of certain frequencies cannot propagate along directions perpendicular to the fiber axis but instead are free to propagate along its length confined to the fiber core. This phenomenon that forbids the propagation of photons transverse to the axis of micro-structured fibers, led to the christening of these specialty fibers as photonic bandgap-guided optical fibers, in analogy with the electronic bandgaps encountered by electrons in semiconductors. In contrast to the electronic bandgap that is the consequence of periodic arrangement of atoms/molecules in a semiconductor crystal lattice, photonic bandgap arises due to a periodic distribution of refractive index in certain dielectric structures, generically referred to as photonic crystals.
Bragg fibers, consisting of a low index core (including air) surrounded by a series of periodic l... more Bragg fibers, consisting of a low index core (including air) surrounded by a series of periodic layers of alternate high and low refractive index materials, each being higher than that of the core, form a 1D photonic bandgap (PBG). In view of the multitude of individual physical parameters that characterize a Bragg fiber, they offer a wide choice of parametric avenues to tailor their propagation characteristics. Owing to their unique PBG guidance mechanism, Bragg fibers indeed exhibit unusual dispersion characteristics that are otherwise nearly impossible to achieve in conventional silica fibers. Solid core Bragg fibers, amenable to fabrication by the highly mature MCVD technology, could be designed to realize broadband supercontinuum light. This talk would review our recent works on modeling of propagation characteristics, dispersion tailoring in them for applications as metro as well as dispersion compensating fibers and also as supercontinuum light generators.
12th International Conference on Fiber Optics and Photonics, 2014
Microstructured-core double clad plastic fiber (MC-DCPF)-based efficient THz source is designed a... more Microstructured-core double clad plastic fiber (MC-DCPF)-based efficient THz source is designed at 3 THz by exploiting non-linear four-wave mixing. Maximum power transfer efficiency > 3×10-2 is achievable in the 65 meter long proposed MC-DCPF.
This chapter presents the evolutionary trends in the design of single-mode optical transmission f... more This chapter presents the evolutionary trends in the design of single-mode optical transmission fibers, in particular for light-wave communication. Multimode fibers in the form of plastic fibers, which hold promise for on-premise and other applications, are discussed. Development of optical fiber technology is considered a major driver behind the information technology revolution and the tremendous progress on global telecommunications that has been witnessed in the past. Fiber optics is the most suitable singular transmission medium for voice, video, and data signals. Indeed, optical fibers have now penetrated virtually all segments of telecommunication networks, whether transoceanic, transcontinental, intercity, metro, access, campus, or on-premise. The Internet revolution and deregulation of the telecommunication sector from government controls that took place almost globally in the past, have substantially contributed to this unprecedented growth within such a short time that was rarely seen in any other technology. The next revolution in light-wave communication took place when broadband optical fiber amplifiers in the form of erbium-doped fiber amplifiers (EDFA) were developed in 1987.
We report an accurate and simple numerical matrix technique for the analysis of ARROW (anti‐reson... more We report an accurate and simple numerical matrix technique for the analysis of ARROW (anti‐resonant and reflecting optical waveguides). All the relevant parameters for the structure of the ARROW have been studied. The accuracy of the method has been established by comparing results with previously reported exact results. The technique proves to be a powerful tool for the design of complicated devices on the ARROW, thereby providing an accurate design tool for scaling a large number of devices on the ARROW chip.
Abstract Design features, for very low bend and splice losses, in dispersion-shifted dual-shape c... more Abstract Design features, for very low bend and splice losses, in dispersion-shifted dual-shape core (DSC) single-mode fibers are obtained in terms of characteristic mode spot sizes Wresponsible for splice loss, and W∞ responsible for bend loss. Dual-shape core fiber ...
A novel method to determine the optical properties, namely, absorption coefficient, scattering co... more A novel method to determine the optical properties, namely, absorption coefficient, scattering coefficient, and anisotropy factor of turbid solutions, single constituent or multiconstituent, is presented. Turbid solutions of milk, ink, and a mixture of both were illuminated by a laser beam and measurements were carried out in scattered light. Experimental results were matched to the corresponding results of Monte Carlo simulation to obtain the optical properties of the turbid media.
We propose a novel SOI rib horizontal slot waveguide geometry to achieve larger than 10% enhancem... more We propose a novel SOI rib horizontal slot waveguide geometry to achieve larger than 10% enhancement in evanescent field vis-a-vis a conventional horizontal slot waveguide and hence yielding higher sensitivity in its environment sensing applications.
Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XI, 2018
We have numerically demonstrated refractive index sensing using terahertz metamaterials comprised... more We have numerically demonstrated refractive index sensing using terahertz metamaterials comprised of single split gap resonators. Sensing capabilities of odd and even order resonance modes are precisely investigated. In this scheme the top surface of metamaterials array is covered with a thin layer of polyimide whose refractive could be changed manually. The sensitivity and corresponding figure of merit (FoM) of several lowest order modes are examined with respect to the different thicknesses of the coated polyimide film. We have investigated the electric field distributions at different resonances for the MMs. Although we have mainly focused on refractive index sensing but this study could be extremely useful for the development of metamaterials based sensing devices, bio-sensors etc.
Co-existence and interplay between mesoscopic light dynamics with singular optics in spatially di... more Co-existence and interplay between mesoscopic light dynamics with singular optics in spatially disordered waveguide lattices is reported. Disorder induced singular behavior and diffusive wave propagation are quantitatively analyzed.
International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '96, 1998
Low-loss high-silica fibers were first reported in 1970 and since then these glass fibers have pr... more Low-loss high-silica fibers were first reported in 1970 and since then these glass fibers have proven to be the most viable transmission media for lightwave communication. Even though the first low loss fiber was a single-mode fiber, initial systems revolved around multimode fibers from the point of view of practical reasons like easier fiber to fiber splicing and coupling from off-the-shelf available LEDs. Since early 1980s, single-mode fibers became the preferred media for optical transmission and single-mode fibers overtook the multimode fibers for lightwave communication. Networks which operate with single-mode fibers at the 1.31 /mm low-loss wavelength window are now taken for granted. Operations with advanced fiber designs at the silica fiber’s lowest loss window of 1.55 /mm are now gearing to take over the long-haul routes; these are contemplated to be based on erbium doped fiber amplifiers (EDFA) and dispersion shifted fibers. An alternative and promising scheme for this wavelength window involving use of already laid fibers optimized for 1.31 /an requires insertion of a dispersion compensating fiber(DCF) as an additional component in the link. In the immediate future, lightwave systems would operate with EDFA at the OC-48 level, which amounts to a bit rate of — 2.5 Gb/s and are compatible with SDH (STM-16) networks. For WDM transmission with EDFAs, one would require a variety of in-line fiber components like wavelength selective couplers, and bandpass/bandstop filters to add/drop channels. Until recently, optical fibers were considered to be optically linear. However, with the introduction of EDFAs, which provide large and broadband (* 30-35 nm) optical gains, a large number of WDM information channels can be transmitted and simultaneously provided gains across this broad gain spectrum of EDFAs. Furthermore, amplifier spacings could be much longer than the present day regenerator spacings. These two fall outs of EDFA namely, large optical power density and long interaction lengths have elevated optical fiber nonlinearities to an important design issue in lightwave systems. In this presentation we would aim to trace the evolutionary trends in lightwave communications seen along the above lines since the reporting of the first low-loss fibers a quarter century ago. INTRODUCTION
2012 5th International Conference on Computers and Devices for Communication (CODEC), 2012
The huge progress already seen in optical fiber communication by the late 1990s led one to questi... more The huge progress already seen in optical fiber communication by the late 1990s led one to question `Is there any scope for further research in optical fibers?' The answer however turned out to be `indeed yes'. There emerged a resurgence of interest to design and fabricate exotic class of specialty fibers, in which transmission losses of the material would not be a limiting factor while nonlinearity and dispersion characteristics could be conveniently tailored. Research targeted towards such fiber designs led to the emergence of a new class of fibers, broadly referred to as microstructured optical fibers, which are characterized by wavelength-scale refractive index features across its physical cross-section resulting in photonic bandgaps when appropriately designed. This talk would focus on our research in recent years on designs of a variety of such photonic bandgap fibers for a variety of applications such as dispersion compensating fibers, metro fibers, supercontinuum (SC) light generating fibers, parabolic pulse generating fibers for fiber lasers, almost non-dispersive propagation of ultra-short light pulses for biomedical applications, large mode area soft-glass based fibers for mid-infrared wavelengths, and chalcogenide fiber-based mid-ir fibers as light source, SC generator, and for high power delivery.
This chapter describes the history, underlying physics, modeling of propagation characteristics, ... more This chapter describes the history, underlying physics, modeling of propagation characteristics, design issues, and fabrication of 1D photonic bandgap-guided bragg fibers (PBGF). It has indeed emerged as a specialty fiber with the potential for several attractive applications. In a conventional optical fiber, light is guided by total internal reflection because of the refractive index contrast that exists between a finite-sized cylindrical core and the cladding of lower refractive index that surrounds it. Whereas, in a PBGF, light of certain frequencies cannot propagate along directions perpendicular to the fiber axis but instead are free to propagate along its length confined to the fiber core. This phenomenon that forbids the propagation of photons transverse to the axis of micro-structured fibers, led to the christening of these specialty fibers as photonic bandgap-guided optical fibers, in analogy with the electronic bandgaps encountered by electrons in semiconductors. In contrast to the electronic bandgap that is the consequence of periodic arrangement of atoms/molecules in a semiconductor crystal lattice, photonic bandgap arises due to a periodic distribution of refractive index in certain dielectric structures, generically referred to as photonic crystals.
Bragg fibers, consisting of a low index core (including air) surrounded by a series of periodic l... more Bragg fibers, consisting of a low index core (including air) surrounded by a series of periodic layers of alternate high and low refractive index materials, each being higher than that of the core, form a 1D photonic bandgap (PBG). In view of the multitude of individual physical parameters that characterize a Bragg fiber, they offer a wide choice of parametric avenues to tailor their propagation characteristics. Owing to their unique PBG guidance mechanism, Bragg fibers indeed exhibit unusual dispersion characteristics that are otherwise nearly impossible to achieve in conventional silica fibers. Solid core Bragg fibers, amenable to fabrication by the highly mature MCVD technology, could be designed to realize broadband supercontinuum light. This talk would review our recent works on modeling of propagation characteristics, dispersion tailoring in them for applications as metro as well as dispersion compensating fibers and also as supercontinuum light generators.
12th International Conference on Fiber Optics and Photonics, 2014
Microstructured-core double clad plastic fiber (MC-DCPF)-based efficient THz source is designed a... more Microstructured-core double clad plastic fiber (MC-DCPF)-based efficient THz source is designed at 3 THz by exploiting non-linear four-wave mixing. Maximum power transfer efficiency > 3×10-2 is achievable in the 65 meter long proposed MC-DCPF.
This chapter presents the evolutionary trends in the design of single-mode optical transmission f... more This chapter presents the evolutionary trends in the design of single-mode optical transmission fibers, in particular for light-wave communication. Multimode fibers in the form of plastic fibers, which hold promise for on-premise and other applications, are discussed. Development of optical fiber technology is considered a major driver behind the information technology revolution and the tremendous progress on global telecommunications that has been witnessed in the past. Fiber optics is the most suitable singular transmission medium for voice, video, and data signals. Indeed, optical fibers have now penetrated virtually all segments of telecommunication networks, whether transoceanic, transcontinental, intercity, metro, access, campus, or on-premise. The Internet revolution and deregulation of the telecommunication sector from government controls that took place almost globally in the past, have substantially contributed to this unprecedented growth within such a short time that was rarely seen in any other technology. The next revolution in light-wave communication took place when broadband optical fiber amplifiers in the form of erbium-doped fiber amplifiers (EDFA) were developed in 1987.
We report an accurate and simple numerical matrix technique for the analysis of ARROW (anti‐reson... more We report an accurate and simple numerical matrix technique for the analysis of ARROW (anti‐resonant and reflecting optical waveguides). All the relevant parameters for the structure of the ARROW have been studied. The accuracy of the method has been established by comparing results with previously reported exact results. The technique proves to be a powerful tool for the design of complicated devices on the ARROW, thereby providing an accurate design tool for scaling a large number of devices on the ARROW chip.
Abstract Design features, for very low bend and splice losses, in dispersion-shifted dual-shape c... more Abstract Design features, for very low bend and splice losses, in dispersion-shifted dual-shape core (DSC) single-mode fibers are obtained in terms of characteristic mode spot sizes Wresponsible for splice loss, and W∞ responsible for bend loss. Dual-shape core fiber ...
A novel method to determine the optical properties, namely, absorption coefficient, scattering co... more A novel method to determine the optical properties, namely, absorption coefficient, scattering coefficient, and anisotropy factor of turbid solutions, single constituent or multiconstituent, is presented. Turbid solutions of milk, ink, and a mixture of both were illuminated by a laser beam and measurements were carried out in scattered light. Experimental results were matched to the corresponding results of Monte Carlo simulation to obtain the optical properties of the turbid media.
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Papers by B.P. Pal