Qualification: 
Ph.D
viswassnair@am.amrita.edu

Dr. Viswas S. Nair serves as Assistant Professor at Amrita Vishwa Vidyapeetham. He received his B.Tech in Electronics and Communication Engineering from Rajiv Gandhi Institute of Technology, Kottayam (2006). His higher education includes M.E. Communication Engineering from BITS Pilani (2009) and Ph.D. in Electrical Engineering from IIT Kanpur (2017). He also spent some time with VSNL Mumbai, Intel Technology India Pvt. Ltd., and CSIR-CEERI-Pilani. Viswas is currently involved in teaching/research related to optoelectronics, solid-state devices, and optical communication.

Degree Name of the University Year of Passing
PhD. IIT Kanpur 2017

Publications

Publication Type: Journal Article

Year of Publication Publication Type Title

2018

Journal Article

Viswas Sadasivan and Das, U., “Nonlinear tuning in InGaAsP Embedded Rings”, Optical and Quantum Electronics, vol. 50, no. 2, p. 76, 2018.[Abstract]


Embedded Rings (ER) have been fabricated on InGaAsP/InP multi-quantum wells (MQW) using electron beam lithography and methane + hydrogen reactive ion etching through Cr/SiO2 etched mask. The ER showed a spectrum with interfering resonance modes which has been positively compared with simulation. The device has been used to demonstrate low speed nonlinear tuning of 2 nm with 10 mW input optical power.

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2016

Journal Article

Viswas Sadasivan, Dagar, S., and Bhowmick, T., “InGaAsP/InP integrated waveguide photodetector pair using quantum well intermixing”, Optical and Quantum Electronics, vol. 48, 2016.[Abstract]


Quantum well intermixing using single layer ZrO2 capped annealing on InGaAsP/InP MQW has been used to achieve integrated two wavelength photodiode pair. The selective solubility of In and Ga in ZrO2 has been used for bandgap engineering. The top layers of the hetrostructure is chosen by lithography and etching into the same hetrostructure. The regions with lower desired bandgaps are chosen to be of lower Ga content. Comparison of different top layer and anneal conditions with respect to wavelength shift and surface quality is also shown. A uniform F ion implantation performed before the annealing has shown an increase of differential blue shift. Regions with up to a minimum of 60 nm InGaAs top layer have been shown to produce a differential bandgap change of 10 nm with no F ion implantation, and 30 nm with uniform F ion implantation (when annealed at 750 °C for 10 s with 300 nm ZrO2 cap).

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2015

Journal Article

Viswas Sadasivan, Dagar, S., and Das, U., “Fabrication of low grass, smooth sidewall InGaAsP by methane–hydrogen inductively coupled plasma RIE through a metal lift-off mask patterned by e-beam lithography”, Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society, vol. 33, p. 051210, 2015.[Abstract]


An optimized CH4+H2 inductively coupled-plasma reactive-ion-etching process for fabrication of high quality nanophotonic InGaAsP/InP waveguide device has been developed. Important parameters that influence e-beam lithography and etching have been optimized for a simple metal lift-off masked process. Smooth sidewalls with low grass content has been demonstrated for >3 μm etch depths in InGaAsP/InP using an Al lift-off etch mask.

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2014

Journal Article

Viswas Sadasivan and Das, U., “QCSE tuned embedded ring modulator”, Lightwave Technology, Journal of, vol. 32, pp. 107-114, 2014.[Abstract]


A micro embedded ring resonator modulator using quantum confined stark effect (QCSE) has been modeled and studied in this paper. Semi analytical design methods for various components like bend, coupler, and the whole embedded ring have been used here. Time domain and frequency domain analysis methods have been developed and studied. Using these methods a 50 Gbps, 11 dB extinction ratio, 5 μm outer radius embedded ring, QCSE tuned optical modulator design has been proposed.

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Publication Type: Patent

Year of Publication Publication Type Title

2016

Patent

Viswas Sadasivan and Das, U., “Low loss fast electro-optically or all-optically tuned embedded ring modulator or filter”, 2016.[Abstract]


Application Number:1519/DEL/2014 (Indian patent)

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Publication Type: Conference Paper

Year of Publication Publication Type Title

2016

Conference Paper

Viswas Sadasivan and Das, U., “Embedded ring resonator in InGaAsP multi-quantum wells”, in 13th International Conference on Fiber Optics and Photonics, Kanpur India, 2016.[Abstract]


Embedded ring (ER) is fabricated on InGaAsP/InP multi-quantum wells using electron beam lithography and methane hydrogen reactive ion etchinG.Experimental findings of this ER are also compared with the theoretical study.

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2015

Conference Paper

Viswas Sadasivan and Das, U., “Fabrication of InGaAsP/InP nano-photonic ridge waveguides using CH4+H2 ICP RIE and Al lift-off mask”, in International Workshop on the Physics of Semiconductor Devices 2015 (IWPSD-15), Bangalore, 2015.

2015

Conference Paper

Viswas Sadasivan and Das, U., “Embedded ring high speed modulators and switches”, in International Conference on Computers and Devices for Communication(CODEC-15), Kolkata, India, 2015.

2014

Conference Paper

Viswas Sadasivan and Das, U., “Optical switching in InGaAsP/InP Embedded Ring Resonators”, in International Conference on Fibre Optics and Photonics, 2014, 2014.[Abstract]


A simulation of embedded ring resonators for intensity dependent nonlinearity in InGaAsP/InP hetrostructure has been carried out. A narrow band all-optical switching of 14dB is obtained for an input power of 100mW.

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2014

Conference Paper

Viswas Sadasivan and Das, U., “Parameter variation in QCSE tuned embedded ring resonator”, in IEEE Region 10 Symposium (TENSYMP-14), Kuala Lumpur, Malaysia, 2014.[Abstract]


Micro embedded ring resonator using Quantum Confined Stark Effect (QCSE) is studied for its parameter variations with respect to spectral shape and modulation speed. The effects of number of quantum wells, coupling coefficient, ring detuning, symmetry of the structure and temperature on the spectrum are studied here.

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