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Kapil Debnath


Dr. Debnath is an Assistant Professor at the Electronics and Electrical Engineering Department of IIT Kharagpur. His research activities are in the field of Integrated Photonics and over the last decade, he has been involved in many disruptive technologies in this area. He completed his BTech in Electronics & Telecommunication Engineering from NIT Silchar in 2004 and MTech in Applied Optics from IIT Delhi in 2009. He carried out his PhD research at the University of St Andrews under the guidance of Prof. Thomas Krauss from 2009-2013.  During his PhD, he developed a novel optical interconnect architecture which would be suitable for both on-chip and off-chip communications. The architecture is based on Photonic Crystal Cavities, which is equally capable of modulating and detecting electrical signals to/from the optical signal. Using this technology, he demonstrated electro-optic modulators with world’s lowest switching energy. In 2013, his patented architecture resulted in a proof-of-concept project, funded by Scottish Enterprise. During his stay at the University of St Andrews, he was also awarded a research grant from EPSRC to address the incompatibility issue between electronic and photonic platforms. In 2015, he moved to the University of Southampton and worked as a postdoctoral research fellow with Prof. Graham Reed and Prof. Shinichi Saito. At the University of Southampton, he developed a unique fabrication process and demonstrated a capacitive silicon modulator with modulation speed up to 25Gbps. Currently, this design is industrially funded for potential commercialization. He has authored 18 international journal publications with 4 patents.

Research Statement

My research goal is to explore various optoelectronic platforms for applications towards energy-efficient communication systems, renewable energy, quantum technology. I am currently interested in the following research directions: (a)On-chip optical communication, (b) ultra-low-power lasers, (c) Integrated nonlinear photonics, (d) 3D photonic crystals, (e) Solar photovoltaics, (f) Quantum technology. For details please visit my website.


  • 1 Solar Photovoltaics
  • 2 Nanofabrication
  • 3 Nanoscale Optoelectronics
  • 4 Fiber Optics And Photonics
  • 5 Photonic Crystals


  • All-silicon carrier accumulation modulator based on a lateral MOS-capacitor, All-silicon carrier accumulation modulator based on a lateral MOS-capacitor, Photonics Research, 6, 373-379, 2018
  • Sotto M., Debnath K. , Khokhar A. Z., Tomita I. , Thomson D. , Saito S., Anomalous zero-group-velocity photonic bonding states with local chirality, Journal of the Optical Society of America B, 35, 2356-2363, 2018
  • Sotto M., Tomita I. , Debnath K. , Saito S., Polarisation Rotation and Mode Splitting in Photonic Crystal Line-Defect Waveguide, Frontiers in Physics, 6, 1-9, 2018
  • Osman A., Nedeljkovik M. , Soler Penades J. , Wu Y. , Qu Z. , Khokhar A. Z., Debnath K. , Mashanovich G. Z., Suspended low-loss germanium waveguides for the longwave-infrared, Optics Letters, 43, 5997-6000, 2018
  • Debnath K., Khokhar A. Z., Reed G. T., Saito S., Fabrication of Arbitrarily Narrow Vertical Dielectric Slots in Silicon Waveguides, Photonics Technology Letters, 29, 1269-1272, 2017
  • Debnath K., Bucio T. D., Al-attili A. A., Khokhar A. Z., Saito S. , Gardes F. Y., Photonic crystal waveguides on silicon rich nitride platform, Optics Express, 25, 3214-3221, 2017
  • Debnath K., Clementi M. , Bucio T. D., Khokhar A. Z., Sotto M. , Grabska K. M., Bajoni D. , Galli M. , Saito S. , Gardes F. Y., Ultrahigh-Q photonic crystal cavities in silicon rich nitride, Optics express, 25, 27334-27340, 2017
  • Liles A., Debnath K. , O'faolain L, Frontiers in Materials, Optics Letters, 41, 894-897, 2016
  • Debnath K., Khokhar A. Z., Boden S. A., Arimoto H. , Oo S. Z., Chong H. M., Reed G. T., Saito S., Low-loss slot waveguides with silicon (111) surfaces realized using anisotropic wet etching, Frontiers in Materials, 3, 2016
  • Debnath K., Moore R. , Liles A. , O'faolain L., Toolkit For photonic integrated circuits based on inverted rib waveguides, Journal of Lightwave Technology, 33, 4145-4150, 2015
  • Debnath K., Welna K. , Ferrera M. , Deasy K. , Lidzey D. G., O L., Highly efficient optical filter based on vertically coupled photonic crystal cavity and bus waveguide, Optics Letters, 38, 154-156, 2013


  • Fabrication Method of Photonic Crystals for Three-dimensional Manipulation of Photons, Client: Science and Engineering Research Board (SERB), P.I.: Kapil Debnath, Completed
  • High - Resolution Broadband On - Chip Micro - Spectrometer, Client: ISIRD, SRIC, P.I.: Kapil Debnath, Completed


  • One of the finalists in the “UK ICT Pioneers” competition held by EPSRC in London, UK. - Year: 2012
  • Winner of the prize for best student poster presentation during the “Group Four Photonics” conference in San Diego, USA. - Year: 2012
  • 2 nd Prize for 2nd year School of Physics and Astronomy PhD student talk - Year: 2011


  • Wave vector matched resonator and bus waveguide system
  • Optical Modulator with Plasmon Based Coupling
  • External cavity laser comprising a photonic crystal resonator
  • “Dielectric slot in optical waveguide for electro-optic modulator and method of fabrication

Research Group

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Ipsita Chakraborty
Ph. D.
Research Scholars
Microwave photonics
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Rina Mudi
Ph. D.
Research Scholars
Photonic Crystal
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Shuvajit Roy
Ph. D.
Research Scholars
Integrated Photonics