Professor, Dept. of Electronics & Communication at Malaviya National Institute of Technology
Scholarship Committee |
Area of Expertise:
Optical switches, couplers, spitters, logic gates and circuits ,
Integrated Photonics ,
Microring resonator based optical devices and systems ,
Non linear characteristics of Photonic Crystal Fibers ,
Nano Photonics ,
Prof. (Dr.) Ghanshyam Singh, an recipient of Distinguished Lecturer Award from IEEE Photonics Society for term 2017-18, has received B. Tech. degree in Electronics and Communication Engineering from NIT Silchar (then REC Silchar), M. Tech. and PhD degrees in Electronics and Communication Engineering from Malaviya National Institute of Technology (MNIT) Jaipur. In early 1999, he joined the academic staff of MNIT Jaipur, where he is a Professor with the Department of EC Engineering. He had worked as visiting research scholar/visiting professor in the area of Photonic Switching and Networks for various periods at the Department of Physics, Herriot Watt University, Edinburgh, UK (March 2009), the Institute of Photonics, University of Eastern Finland, Joensuu, Finland (2010) under the CIMO Fellowship (Govt. of Finland) and Department of EEE, Keio University, Hiyoshi Campus, Yokohama, Japan (October 2013). Dr. Singh has extensive teaching, research and sponsored R&D experience on many aspects of Optical Communication and Photonics Technologies and has published/reported over 125 research papers/review articles in peer reviewed International journals/ conferences. He had delivered expert talks on related research topics during various events held in India and abroad (including Germany, Finland, UK, Singapore, Japan, Hong Kong, Ukraine, Belarus, China, Australia, Malaysia, Poland, Italy, France, Spain, Portugal and USA). Dr. Singh is a senior member of SPIE, OSA, IEEE and Fellow of OSI and IETE and member of ISTE, IE (India), etc. Presently, Dr. Singh have done joint projects with partner researchers from Keio University (Japan), University of Vienna (Austria), LNPU Lviv (Ukraine) and Cairo University (Egypt) and Presently engaged with researchers from Russia, South Africa and China. His current research interest includes Micro and Nano-structured Photonic Devices, Photonic Crystal Fibers, Integrated Photonics, Photonics Sensors, AI applications in Photonics, etc.
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When a patch antenna is fabricated, dimensions of the patch may be slightly different from the designed values due to tolerances in the fabrication process. This alters the resonance frequency of the antenna. To overcome this problem this paper presents a new design approach for fine tuning the resonance frequency by dielectric constant engineering. This approach is especially suited to low temperature co-fired ceramic (LTCC) and similar processes where the antenna dielectric is composed of several layers. Composite dielectric constant of this multilayer structure is altered in such a way that the resonant frequency is set back to the designed value. It has been verified that for proposed micro strip antenna (MSA) design, the frequency-area curve follows a quadratic relation with a variable R (Ratio of cavity area to the patch area). This mathematical model is true up to R 1.27. After this saturation effects set in and the curve follows a straight line behavior.≡
A flat Nano-metallic (Silver) surface plasmonic lens for wider optical wavelength operation based on the phase and
amplitude modulation by tuning the slit widths is introduced. The design novelty lies on its complex structure with the
macro-parameters such as focal length with freedoms in its material profile, thickness, slit width and the pitch. A
simplified implementation of the Nano-metallic lens with equidistant slits but bearing different widths is evaluated using the finite difference time domain method. The design tolerance and variation in the focal point position in accordance to alteration in the properties of the lens are explored in brief.
Novel index-guiding photonic crystal fibers (PCF) with rings of cladding holes (circularly or elliptically shaped) arranged in the Fibonacci series are proposed. The dispersion, confinement losses, and generated birefringence in PCFs are evaluated for light signal at 1.55-µm wavelength, by employing alterations in various design parameters. Full-vector analysis using anisotropic perfectly matched layers is performed to validate the accuracy of the modeled PCFs in a finite-difference time-domain environment. For such PCF modeling, the lower value of dispersion is found to be 7.311 ps nm−1 km−1, and the zero-dispersion wavelength is shifted to lower infrared region in accordance with variation in the hole diameter-to-pitch ratio.
Modeling and detailed performance analysis is carried out to realize a multimode interferometer optical switch by inserting an appropriate image-modulated (IM) region. The concept of self-imaging characteristics of multimode waveguides has been utilized in order to drive the designed device as a photonic switch. Transition losses in the waveguides of the structure are maintained at low levels by selecting appropriate dimensions to increase overall performance of the switch. It has been observed that by inserting an additional IM region, switching losses and corresponding crosstalk levels can be reduced significantly. The device performance is checked for a wider range of index variation in the IM region with respect to other regions for a test wavelengh of 1.55 µm. With rigorous and repetitive simulation, a crosstalk level better than -22.2 dB for either case of polarization state (transverse electric and transverse magnetic) of input has been achieved. The design also possesses a design tolerance in the range of ±0.25 to ±0.5 μm, within which variation in the imaging length and its subsequent adverse effects on device performance remains less than 1.5%.
Modelling of a compact and completely non-blocking 4×4 optical switch utilizing integrated multi-mode interference (MMI) waveguides with a channel profile of Ti-indiffused Lithium Niobate is described. Design novelty lies in its satisfactory operation for two wide optical windows (100 nm each), with center wavelengths (λcentre) of 1.3 and 1.55 µm, possessing low losses. For either of these windows, the average value of propagation losses are maintained lower than 1 dB with a vacillation of extremely low polarization dependent losses ( ≤ 0.15 dB). Index tuned regions are optimized to achieve average crosstalk levels better than −19 and −12 dB for its operation in the wavelength range of 1.25 to 1.35 µm and 1.50 to 1.60 µm, respectively. It is also observed that switch possess absolute loss uniformity (of the range of 0.5% to 1.6%) with a maximum of ±2.5% tolerance in the structural parameters.
This paper describes the modeling of a 2×2 multimode interference (MMI) switch, with a channel profile of
Titanium indiffused Lithium Niobate. Design novelty lies in its satisfactory operation for two wide optical
windows (100nm each with centre wavelengths, λcentre of 1.3 μm and 1.55 μm) with low switching losses and
crosstalk levels. Index tuned regions are optimized to achieve crosstalk levels of ≥ -18 dB and ≥ -14 dB for its
operation in the wavelength range of 1.25 μm - 1.35 μm and 1.50 μm - 1.60 μm respectively. For either of
these wavelength ranges, the switch losses (excess and insertion losses) are maintained lower than 1 dB.
A diffusion process controlled modelling of Titanium-indiffused Lithium Niobate (Ti: LiNbO3) channel waveguides
(of μm dimension) for Machzehnder Interferometer (MZI) switch has been presented. The effect of various
indiffusion process parameters e.g. dopant strip thickness, lateral and vertical diffusion length on the insertion loss has
been taken care of, to reduce the switch losses. Transition losses in the curved waveguides of the structure are also
minimized by selecting low loss bend structures to increase overall performance of the switch. The computed results
for switch performance are in good agreement with the published data.
This paper reviews the development of hydrogen silsesquioxane nanostructures (sub-100nm) on a silicon platform.
The effect of HSQ resist in thick (128nm thick resist) and thinner state (30nm thick resist) has been demonstrated and
minimum possible structures with these are discussed in details. Most applicable structures like straight lines/spaces,
sharp joints/corners and dots were developed to investigate the effects of development time on the lithography
properties of HSQ. Soft bake after spinning process had been avoided in view of achieving better contrast and stable
resist deposition. We had also reached to a conclusion that increasing the development time could improve resist
contrast and pattern resolutions up to certain limits but may vary with type of structures and other conditions.
In this paper, design of an all-optical switch using MZI switching elements with SOA's and its works performance is
explained. The effect of variations of output power with respect to control signal wavelength, data signal power and control
signal power are examined and plotted. Also the optical spectrum and time domain analysis has been done to demonstrate its