Terahertz Optics and Meta-Photonics Lab

Indian Institute of Technology, Guwahati

Journal Publications

    1. LK Vaswani, BS Chouhan, A Panwar, A Bhattacharya, F Moin Gagan Kumar, "Single and dual-band electromagnetically induced transparency in a strongly near field coupled planar toroidal terahertz metamaterial" Optics & Laser Technology (2024)
    2. B Kumar Bhowmik, KM Rohith, S John, S Prabhu Gagan Kumar, "High-quality factor Quasi-BIC mode via selective symmetry-breaking approach in a terahertz metasurface" New Journal of Physics(2024)
    3. B Singh Chouhan, N Acharyya, A Panwar, D Roy Chowdhury, Gagan Kumar, "Multi-stacked polarization insensitive broadband terahertz metamaterial" Journal of Applied Physics(2024)
    4. Maidul Islam, Anshul Bhardwaj, Mainuddin and Gagan Kumar, "Planar terahertz multi-resonator meta-waveguide based upon strongly coupled nested split-ring resonator" Optik(2024)
    5. M Ashraf, Mainuddin, Mirza Tariq Beg, Fiza Moin, Ananta Saikia, Sanjai K Dwivedi and Gagan Kumar, "Comparison of U and coil-shaped fiber sensors for fluoride detection in water" Optical and Quantum Electronics (2024)
    6. B. S. Chouhan, B. Barman, L. K. Vaswani, A. Panwar and Gagan Kumar, "Broadening of Resonance With the Bending of Strongly Coupled Strip Resonators in a Planar Terahertz Metamaterial" Journal of Lightwave Technology(2024)
    7. Rajesh Kumar, Rohith K. M., Shashank Pandey, Sanjeev K. Srivastava, and Gagan Kumar, "Terahertz tunable band-stop filter using topological valley photonic crystals" Appl. Opt. 63, 104-111 (2024)
    8. Bhowmik, Bhairov Kumar, Tanmay Bhowmik, Pranav Kumar Pandey, Makaraju Srinivasa Raju, Debabrata Sikdar, Gagan Kumar et al. "All-dielectric asymmetric planar metasurface based dual-parametric sensor". Optics Communications 550 (2024)
    9. Kaur, R., Islam, M., Agarwal, Gagan Kumar, P.C. et al."Highly confined terahertz spoof plasmon propagation in a parallel plate corrugated waveguide" Journal of Optics (2023).
    10. Tanmay Bhowmik, Bhairov Kr Bhowmik, Pranav Kr Pandey, Gagan Kumar, Debabrata Sikdar "Dual-band electro-optic modulator based on tunable broadband metamaterial absorber" Optics & Laser Technology 161 (2023)
    11. Lavi Kumar Vaswani, Bhagwat Singh Chouhan, Anuraj Panwar, Gagan Kumar"Electromagnetically induced transparency in a strongly coupled orthogonal polarization insensitive planar terahertz metamaterial" Journal of Physics D: Applied Physics (2023).
    12. Ashraf, Mohd,Mainuddin, M., Beg, M. T., Moin, F., Saikia, A., Dwivedi, S. K., Gagan Kumar,"U-shaped plastic optical fiber sensor for phosphate detection in water" Optical and Quantum Electronics 55.13 (2023)
    13. Vaswani, Lavi Kumar, Anuraj Panwar, and Gagan Kumar. "Thermally controllable electromagnetically induced transparency in a coupled terahertz metamaterial" Materials Today: Proceedings (2023)
    14. Bhairov Kumar Bhowmik, Tanmay Bhowmik, Pranav Kumar Pandey, Debabrata Sikdar and Gagan Kumar, "Narrow Bandpass Filter using All-Dielectric Metamaterial in Optical Communication Band". Journal of Optical Society of America B 2023.
    15. Maidul Islam, Anshul Bhardwaj, Bhairov Kumar Bhowmik, Gagan Kumar, "Terahertz Meta-waveguide Based upon Strongly Near-Field Coupled Split-Ring Resonators" Journal of Infrared, Millimeter, and Terahertz Waves, 2023.
    16. Angana Bhattacharya, Bhagwat S Chouhan, Bhairov K Bhowmik, Rajan Singh, Gagan Kumar, "Polarization independent lattice-coupled terahertz toroidal excitations"arXiv:2303.15341
    17. S Jagan Mohan Rao, Rakesh Sarkar, Ajinkya Punjal, Dipa Ghindani, Dibakar Roy Chowdhury, S S Prabhu, and Gagan Kumar, Broadband terahertz linear cross polarization conversion in transmission mode using planar coupled metamaterials, Journal of Applied Physics (JAP) 2023.
    18. Rakesh Sarkar, Angana Bhattachary, Ajinkya Punjal, S S Prabhu, Gagan Kumar, "Broadband terahertz polarization conversion using a planar toroidal metamaterial" Journal of Applied Physics 132 (18), 183103 (2022).
    19. Tanmay Bhowmik, Bhairov Kr. Bhowmik, Pranav Kr. Pandey, Gagan Kumar, and Debabrata Sikdar, "Dual-band Electro-Optic Modulator based on Tunable Metamaterial Broadband Absorber". Optics and Laser Technology 2022 (Accepted).
    20. Rakesh Sarkar, Ajinkya Punjal, Dhanashree Chemate, S. S. Prabhu and Gagan Kumar, “Ultra wideband efficient cross polarization conversion of terahertz wave based on a planar metamaterial”. Journal of Physics D: Applied Physics 55, 355108 (2022).
    21. KM Dhriti, A. K. Chowdhary, Bhagwat Singh Chouhan, Debabrata Sikdar, and Gagan Kumar, “Tunable Terahertz Absorption Modulation in Graphene-assisted Dielectric Metamaterial”. Journal of Physics D: Applied Physics 55, 285101 (2022).
    22. Maidul Islam, Bhoirav Kumar Bhowmik, K. M. Dhriti, Amir Ahmad, and Gagan Kumar, “Thin film sensing characteristics in Terahertz meta-waveguide structure”. Journal of Optics 24, 064016 (2022).
    23. Angana Bhattacharya, Rakesh Sarkar, and Gagan Kumar, “Toroidal resonance-based electromagnetically induced transparency in coupled meta-surfaces and its applications” iScience 25, 103708 (2022).
    24. Jeongwoo Han,…., Gagan Kumar, Rachael L Myers-Ward, Matthew T Dejarld, Kevin M Daniels, H Dennis Drew, Thomas E Murphy and Martin Mittendorff, “Plasmonic terahertz nonlinearity in graphene disks”. Advanced Photonics Research 3, 2100218 (2022) (Wiley).
    25. Angana Bhattacharya, Rakesh Sarkar, and Gagan Kumar, “Multiband transparency effect induced by toroidal excitation in a strongly coupled planar terahertz metamaterial”. Scientific Reports 11, 19186 (2021)
    26. Roopkiranpreet Kaur; Sukhdeep Kaur, Maidul Islam, Gagan Kumar, “Terahertz Surface Plasmons Propagation in Semiconducting Parallel Plates Waveguide Configuration". EPL (Europhysics Letters) 134 (3), 38002 (2021)
    27. Angana Bhattacharya, Rakesh Sarkar and Gagan Kumar, “Excitation of near field coupled dual toroidal resonances in a bilayer terahertz metamaterial configuration.” Journal of Physics D: Applied Physics 54,285102(2021).
    28. KM Dhriti, Maidul Islam, Angana Bhattacharya, Amir Ahmad and Gagan Kumar, “ Plasmon-induced transparency in an air–dielectric grooved parallel-plate terahertz waveguide.” Journal of the Optical Society of America B 38(4),1290-1296(2021)
    29. Maidul Islam, KM Dhriti, Rakesh Sarkar, Gagan Kumar, “ Tunable control of electromagnetically induced transparency effect in a double slot terahertz waveguide.” Optics Communications 483, 126632(2021).
    30. Matthew L Chin, Sebastian Matschy, Florian Stawitzki, Jayaprakash Poojali, Hassan A Hafez, Dmitry Turchinovich, Stephan Winnerl, Gagan Kumar, Rachael L Myers-Ward, Matthew T Dejarld, Kevin M Daniels, H Dennis Drew, Thomas E Murphy, Martin Mittendorff, “ Observation of strong magneto plasmonic nonlinearity in bilayer graphene discs.” J. Phys. Photonics 3 (2021) 01LT01.
    31. A Ahmad, S Garhwal, SK Ray, Gagan Kumar, SJ Malebary, OM Barukab, “The Number of Confirmed Cases of Covid-19 by using Machine Learning: Methods and Challenges”, Archives of Computational Methods in Engineering, 28 (4), 2645-2653 (2021) (DOI:10.1007/s11831-020-09472-8.)
    32. KM Dhriti, Maidul Islam, Gagan Kumar, “Terahertz surface plasmon propagation in a near field coupled asymmetric resonators based planar waveguide.” Journal of Optics,22,125003(2020).
    33. KM Dhriti Maurya, Amir Ahmad, Gagan Kumar, “Planar plasmonic terahertz waveguide based upon one dimensional array of pyramidal corrugations and refractive index sensing.” IEEE Photonics Journal,12,4801010(2020).
    34. Rakesh Sarkar, Koijam Monika Devi, Dipa Ghindani, S.S Prabhu, DR Chowdhury and Gagan Kumar, “Polarization independent double-band electromagnetically induced transparency effect in terahertz metamaterials.” JOurnal of Optics, 22, 035105(2020).
    35. Rakesh Sarkar, Dipa Ghindani, Koijam Monika Devi, S. S. Prabhu, AmirAhmad and Gagan Kumar, “Independently tunable electromagnetically induced transparency efect and dispersion in a multi-band terahertz metamaterial.” Scientific Reports, 9, 18068(2019).
    36. Koijam Monika Devi,Gagan Kumar, and Amarendra K. Sarma, “Surface polaritonic solitons and breathers in a planar plasmonic waveguide structure via electromagnetically induced transparency.” Journal of the optical society of America B 36(8),2160-2166(2019).
    37. Angana Bhattacharya, Koijam Monika Devi, Tho Nguyen and Gagan Kumar,“Actively tunable toroidal excitations in graphene based terahertz metamaterials.” Optics Communications, 124919 (2019).
    38. S. Jagan Mohan Rao, Rakesh Sarkar, Gagan Kumar, and D. R. Chowdhury, “Gradual Cross Polarization Conversion of Transmitted Waves in Near Field Coupled Planar Terahertz Metamaterials.” OSA Continuum 2, 603 (2019).
    39. S Jagan Mohan Rao, Yogesh Srivastava, Gagan Kumar, and Dibakar RoyChowdhury, “Modulating fundamental resonance modes in capacitive coupled asymmetric split gap ring resonator based Terahertz Metamaterials.” Scientific Reports 8, 16773 (2018).
    40. S. Jagan Mohan Rao, Gagan Kumar, Abul K. Azad, and Dibakar Roy Chowdhury, “Ultrafast Resonance Switching in Terahertz Metamaterials through Defect States in Ion implanted Silicon.” ”. Journal of Infrared, Millimeter, and Terahertz Waves 39, 1211 (2018).
    41. Koijam Monika Devi, Amarendra K. Sarma, Dibakar Roy Chowudhury and Gagan Kumar, “Dual-band electromagnetically induced transparency effect in a concentrically coupled asymmetric terahertz metamaterial.” Journal of Applied Physics (AIP) 124, 063106 (2018).
    42. Koijam Monika Devi, Maidul Islam, Amarendra K. Sarma, Dibakar Roy Choudhury and Gagan Kumar, “Plasmon induced transparency in terahertz graphene metamaterial.” EPL (Europhysics Letters) 120 (2), 27005 (2018)
    43. Maidul Islam, Dibakar Roy Chowdhury, Amir Ahmad and Gagan Kumar, “Terahertz plasmonic waveguide based thin film sensor”. Journal of Lightwave Technology 35, 5215 (2017) (DOI: 10.1109/JLT.2017.2763326).
    44. Nipon Deka, Maidul Islam, Prashant K. Sarswat and Gagan Kumar, “Enhancing solar cell efficiency with plasmonic behavior of double metal nanoparticle system Author links open overlay panel." Vacuum 152 285 (2018)
    45. S. Jagan Mohan Rao, Deepak Kumar, Gagan Kumar, and Dibakar Roy Chowdhury, "Modulating the near field coupling through resonator displacement in planar terahertz metamaterials", Journal of Infrared, Millimeter, and Terahertz Waves, 38, 124–134 (2017).
    46. Maidul Islam, Dibakar Roy Chowdhury, Amir Ahmad, and Gagan Kumar, Terahertz guided mode properties in an internally corrugated plasmonic waveguide, AIP: Journal of Applied Physics, 122, 053105 (2017).
    47. Koijam Monika Devi, Amarendra K. Sarma, Dibakar Roy Chowdhury, and Gagan Kumar, Plasmon induced transparency effect through alternately coupled resonators in terahertz metamaterial, Optics Express, 25 (9), 10484-10493
    48. S. Jagan Mohan Rao, Deepak Kumar, Gagan Kumar, Dibakar Roy Chowdhury, Probing  the near field inductive coupling in broadside coupled terahertz metamaterials , IEEE Journal of Selected Topics in Quantum Electronics, 23, 4700707 (2017).
    49. Maidul Islam, S Jagan Mohan Rao, Gagan Kumar, B. P. Pal and Dibakar Roy Chowdhury Role of Resonance modes on Terahertz Metamaterials based thin film sensors has been published in Scientific Reports, 7, 7355 (2017).
    50. Prashant K. Sarswat, Nipon Deka, S Jagan Mohan Rao, Michael L. Free, and Gagan Kumar, Surface Texture-Induced Enhancement of Optical and Photoelectrochemical Activity of Cu2ZnSnS4Photocathodes, Journal of Electronics Materials, 46, 5308-5318 (2017).
    51. Maidul Islam and Gagan Kumar, Terahertz surface plasmons propagation through periodically tilted pillars and control on directional properties.; Journal of Physics D: Applied Physics 49, 435104 (2016).
    52. S. Li, Gagan Kumar, and T. E. Murphy, “Terahertz nonlinear conduction and absorption saturation in silicon waveguides”,1Optica, 2, 553 (2015).
    53. Gagan Kumar, “Controlling terahertz surface plasmon properties on a periodically structured silicon surface”, Journal of Spectroscopy, 2015, 543985 (2015).
    54. Dhiman Bhattacharyya, Prashant K. Sarswat, Maidul Islam, Gagan Kumar, Mano Misra, and Michael L. Free, “Geometrical modifications and tuning of optical and surface plasmon resonance behaviour of Au and Ag coated TiO2 nanotubular array”, RSC Advances, 5, 70361-70370 (2015)
    55. Shanshan Li, Mohammad M. Jadidi, Thomas E. Murphy, and Gagan Kumar, Plasmonic terahertz waveguide based on anisotropically etched silicon substrate;, IEEE Trans. Terahertz. Sci. Technol., 4, 454 (2014).
    56. J. R. Knab, X.-C. Lu, Felipe A. Vallejo, Gagan Kumar, Thomas E. Murphy, and L. Michael Hayden, Ultrafast carrier dynamics and optical properties of nanoporous silicon at broadband terahertz frequencies;, Opt. Mater. Express, 4, 300 (2014).
    57. Manish Kumar, C. S. Suchand Sandeep, Gagan Kumar, Y. K. Mishra, R. Philip, and G. B. Reddy, Plasmonic and Nonlinear Optical Absorption Properties of Ag:ZrO2 Nanocomposite Thin Films;, Plasmonics, 129-136 (2014).9
    58. Gagan Kumar, Shanshan Li, Mohammad M. Jadidi and Thomas E. Murphy, Terahertz Surface Plasmon Waveguide based on a 1-D Array of Silicon Pillars. New Journal of Phys 15, 085031 (2013).
    59. Shanshan Li, Mohammad M. Jadidi, Thomas E. Murphy and Gagan Kumar, Terahertz surface plasmon polaritons on a semiconductor surface structured with periodic V-grooves, Optics Express 21, 7041–7049 (2013). (Corresponding author) (In top downloaded articles March & April 2013, OpEx)
    60. S.-Z. A. Lo, Gagan Kumar, Thomas E. Murphy and Edwin J. Heilweil, Application of nanoporous silicon substrates for terahertz spectroscopy, Opt. Mater. Express 3, 114 (2013).
    61. T. D. Nguyen, S. Liu, Gagan Kumar, A. Nahata, and Z.V. Vardeny, Terahertz plasmonic properties of highly oriented pyrolytic graphite. Appl. Phys. Lett. 102, 171107 (2013)
    62. Y. K. Mishra, R. Adelung, Gagan Kumar, M. Elbahri, S. Mohapatra, R. Singhal, A. Tripathi, and D. K. Avasthi, Formation of self-organized silver nanocup type structures and their plasmonic absorption, Plasmonics 8, 811-815 (2013)
    63. M. Kumar, C. S. S. Sandeep, Gagan Kumar, Y.K. Mishra, R. Philip and G.B. Reddy, Plasmonic and non-linear optical properties of Ag:ZrO2 nanocomposite thin films.  Plasmonics, 2013.
    64. P. K. Sarswat,, M. L. Free, Gagan Kumar, An investigation of nanocrystalline and electrochemically grown Cu2ZnSnS4 thin film using redox couples of different band offset, Journal of Spectroscopy  2013,  321483 (2013)
    65. Gagan Kumar, Albert Cui, Shashank Pandey, and Ajay Nahata, Planar Plasmonics Terahertz waveguide based on periodically corrugated metal films, New J.  Phys. 13, 033024 (2011) (Selected for Research Highlights in Nature Photonics 5, 327, June 2012.)
    66. Wenqi Zhu, Amit Agrawal, Albert Cui, Gagan Kumar, and Ajay Nahata, Engineering the propagation properties of planar plasmonic terahertz waveguides, IEEE J.  of Select . Topics Quant. Electron, 17, 146 (2011). (Invited) 
    67. Gagan Kumar, Shashank Pandey, Albert Cui, and Ajay Nahata, Planar terahertz waveguides based on complementary split ring resonators, Optics Express, 19, 1072 (2011)
    68. M. J. Hagmann, Gagan Kumar, Shashank Pandey, and Ajay Nahata, Analysis and simulation of generating terahertz surface waves on a tapered field emission tip, J. Vac. Sci. Technol. B, 29, 02B113 (2011).
    69. Shashank Pandey, Gagan Kumar, and Ajay Nahata, Slot Waveguide-Based Splitters for Broadband Terahertz Radiation, Optics Express, 18, 23466 (2010).
    70. Gagan Kumar and V. K. Tripathi, Excitation of surface plasma wave over plasma cylinder by a relativistic electron beam, Phys. Plasmas, 15, 073504 (2008).
    71. Gagan Kumar and V. K. Tripathi, Anomalous absorption of surface plasma wave by particles adsorbed on metal surface, Appl. Phys. Lett., 91, 161503 (2007). 
    72. C. S. Liu, Gagan Kumar, D. B. Singh and V. K. Tripathi, Electron acceleration by surface plasma waves in double metal surface structure, J. Appl. Phys. 102, 113301 (2007).
    73. D. B. Singh, Gagan Kumar, and V K Tripathi, Probing of a surface plasma wave by an obliquely incident laser on the metal surface, J. Appl. Phys. 101, 043306 (2007). 
    74. D. B. Singh, Gagan Kumar, and V K Tripathi, Nonlinear absorption of surface plasmons and emission of electrons from metallic targets, Phys. Plasmas., 14, 102108 (2007).
    75. Gagan Kumar and V. K. Tripathi, Filamentation of a surface plasma wave over a semiconductor free space interface, J. Appl. Phys. 102, 123301 (2007).
    76. C. S. Liu, Gagan Kumar, V. K. Tripathi, Laser mode conversion into a surface  plasma wave in a metal coated optical fiber, J. Appl. Phys. 100, 013304 (2006).
    77. Gagan Kumar, D. B. Singh, V. K. Tripathi, Surface enhanced Raman scattering of a surface plasma wave, J. Phys. D: Appl. Phys. 39, 4436-4439 (2006).

    Conference Papers 

    1. Angana Bhattacharya, Gagan Kumar "Quality factor enhancement via lattice coupled toroidal mode in a terahertz metamaterial" SPIE
    2. Bhairov Kumar Bhowmik, Tanmay Bhowmik, Chandan Kumar, Pranav Kumar Pandey, Makaraju Srinivasa Raju, Debabrata Sikdar, Gagan Kumar, Design and Simulation of a Narrow Band-Pass Filter Using a Planar Dielectric Metasurface" Photonics 2023, IISc Banglore. July 5-8, 2023. (Submitted)
    3. Gagan Kumar, Rajesh Kumarand KM Rohith, Design and Control of Topological Valley Edge Modes for Terahertz Photonics". Photonics 2023, IISc Banglore. July 5-8, 2023. (Submitted)
    4. Angana Bhattacharya and Gagan Kumar. "Quality factor enhancement via lattice coupled toroidal mode in a terahertz metamaterial." Conference on Metamaterials, part of SPIE Optics + Optoelectronics. (Submitted)
    5. Bhairov Bhowmik, Tanmay Bhowmik, Pranav Pandey, Debabrata Sikdar, Gagan Kumar, "Polarization-insensitive refractive index sensor based on high-Q resonance in all-dielectric metasurface", Frontiers in Optics + Laser Science (FiO+LS), 18-19 October 2022, Rochester, New York, USA.
    6. KM Dhriti and Gagan Kumar, "Actively controlled two bit Binary Coding in Graphene assisted Terahertz Metasurface", IEEE Photonics conference, November 13-17, 2022, Vancouver 2022. (submitted) (accepted for oral presentation).
    7. KM Dhriti and Gagan Kumar, "Controllable two bit Binary Coding in Graphene assisted Terahertz Metasurface", Frontiers in Optics + Laser Science (FiO+LS) 18-19 October 2022, Rochester, New York, USA. (submitted) (accepted for poster presentation).
    8. Bhagwat Singh Chouhan, KM Dhriti maurya, Bhairov Kumar Bhowmik, Angana Bhattacharya, Gagan Kumar, "Graphene-Dielectric based Tunable Terahertz Polarization Insensitive Modulator", IEEE Photonics conference, November 13-17, 2022, Vancouver 2022. (submitted).
    9. Angana Bhattacharya and Gagan Kumar, "Slow Light Effect in a High Quality Factor Toroidal Mode in a Terahertz Metasurface", Frontiers in Optics + Laser Science (FiO+LS), 18-19 October 2022, Rochester, New York, USA. (submitted)
    10. Bhairov Kumar Bhowmik, Tanmay Bhowmik, Debabrata Sikdar, Gagan Kumar, "High Q resonating all-dielectric metamaterial for refractive index sensing", IEEE Photonics conference, November 13-17, 2022, Vancouver 2022. (submitted)
    11. Tanmay Bhowmik, Bhairov Kr. Bhowmik, Pranav Kr. Pandey, Gagan Kumar, and Debabrata Sikdar, "Epsilon-Near-Zero Material based Dual-Polarization On-Chip Optical Modulator", Frontiers in Optics + Laser Science (FiO+LS), 18-19 October 2022, Rochester, New York, USA. (submitted)
    12. Angana Bhattacharya, Rakesh Sarkar, Ajinkya Punjal, S.S. Prabhu, and Gagan Kumar, "Planar Terahertz Toroidal Meta-Device for Efficient Polarization Conversion", CLEO: QELS_Fundamental Science 2022, San Jose, California, USA, 15–20 May 2022.
    13. Angana Bhattacharya, Kajal Sharma, Gagan Kumar, “Logic Gate Operation based on Terahertz Metamaterial”, IEEE Photonics Conference, November 13-17, 2022 (submitted)
    14. Rakesh Sarkar, Ajinkya Punjal, S.S. Prabhu, Gagan Kumar, "Broadband terahertz polarization conversion in a planar meta-surface" in WRAP 2022 during March 4-6, IIT Bombay.
    15. Roopkiranpreet Kaur, P. C. Agarwal, Sukhdeep Kaur, Gagan Kumar, "Terahertz surface plasmon propagation in metal dielectric metal waveguide with corrugated surface" in WRAP 2022 during March 4-6, IIT Bombay.
    16. Bhagwat Singh Chouhan, KM Dhriti, Ashish Kumar Chowdhary, Debabrata Sikdar, and Gagan Kumar, "Modulating broadband terahertz in a Graphene assisted dielectric Metamaterial" WRAP 2022 during March 4-6, IIT Bombay. (Best oral poster presentation award -Bhagwat)
    17. Bhagwat Singh Chouhan, KM Dhriti, Ashish Kumar Chowdhary, Debabrata Sikdar, Gagan Kumar, "Modulating broadband terahertz in a Graphene assisted dielectric Metamaterial" in WRAP 2022 during March 4-6, IIT Bombay. (Best poster presentation award -Bhagwat)
    18. Bhairov Kumar Bhowmik, Maidul Islam, Gagan Kumar, "Dual-Band Electromagnetic Induced Transparency in a Terahertz Metawaveguide Design" in WRAP 2022 during March 4-6, IIT Bombay.
    19. Angana Bhattacharya, Rakesh Sarkar, Anshul Bhardwaj, Gagan Kumar, “Sensing in a toroidal coupled dual-band EIT terahertz metadevice", in WRAP 2022 , during March 4-6, IIT Bombay.
    20. Dhriti Maurya, Maidul Islam, Gagan Kumar, “Controlling the slow light properties in a corrugated parallel plate terahertz plasmonic waveguide", in WRAP 2022 , during March 4-6, IIT Bombay.
    21. Matthew L Chin, …., Gagan Kumar, Rachael L Myers-Ward, Matthew T Dejarld, Kevin Daniels, Thomas E Murphy, Martin Mittendorff, “Magnetically Tuned THz Nonlinearity in Bilayer Graphene Disc Arrays”", Conference on Laser and Electro Optics (CLEO): Science and Innovations, (STu4G), .May 10-15, 2020, San Jose, California, USA.
    22. Angana Bhattacharya, Koijam Monika Devi, Gagan Kumar, “Toroidal Resonances in Graphene Metamaterials" 2019 Workshop on Recent Advances in Photonics (WRAP); DOI:10.1109/WRAP47485.2019.9013713 IEEE Xplore: 27 February 2020.
    23. Roopkiranpreet Kaur, Manpreet Kaur, PC Agarwal, Sukhdeep Kaur, Gagan Kumar, “Simulation of Terahertz Propagation by TE Mode in Metal Dielectric Metal Waveguide" 2019 Workshop on Recent Advances in Photonics (WRAP); DOI: 10.1109/WRAP47485.2019.9013658 IEEE Xplore: 27 February 2020.
    24. KM Dhriti, Gagan Kumar, “Study of resonant modes for sensing in a multimode planar plasmonic terahertz waveguide" , 2019 Workshop on Recent Advances in Photonics (WRAP); researchgate.net Publication date 2019/12/13.
    25. R Adarsh Bhargav, KM Dhriti, Angana Bhattacharya, Gagan Kumar, “Refractive Index sensing using plasmonic mode in a periodically corrugated waveguide at terahertz frequencies" 2019 Workshop on Recent Advances in Photonics (WRAP); doi:10.1109/WRAP47485.2019.9013714 Publisher IEEE .
    26. Rakesh Sarkar, Dipa Ghindani, Koijam Monika Devi, S Jagan Mohan Rao, SS Prabhu,, Gagan Kumar, “Modulating dual-band electromagnetically induced transparency effect via near field coupling in planar terahertz metamaterials" , 2019 Workshop on Recent Advances in Photonics (WRAP); doi: 10.1109/WRAP47485.2019.9013719 IEEE Xplore: 27 February 2020.
    27. Koijam Monika Devi, Rakesh Sarkar, Amarendra Kumar Sarma, Gagan Kumar, “Exploring polarization independent plasmon induced transparency in a planar terahertz metamaterial" , 2019 Workshop on Recent Advances in Photonics (WRAP); doi: 10.1109/WRAP47485.2019.9013727 IEEE Xplore: 27 February 2020.
    28. Rakesh Sarkar, Koijam Monika Devi, Dipa Ghindani, Ravikumar Jain, Arnab Pattanayak, SS Prabhu and Gagan Kumar, “Dual-band electromagnetically induced transparency effect in asymmetrically coupled terahertz metamaterials" Terahertz, 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), IEEE; 105311K (2019); doi: 10.1109/IRMMW-THz.2019.8874299 IEEE Xplore: 21 October 2019.
    29. S. Jagan Mohan Rao, Rakesh Sarkar, Gagan Kumar and Dibakar Roy Chowdhury, “Asymmetric split gap ring resonator based near field capacitive coupling in terahertz metamaterials”. International Conference on Fiber Optics and Photonics (Photonics 2018). December, 12-15, 2018 in IIT Delhi.
    30. Koijam Monika Devi, Dibakar Roy Chowdhury, Gagan Kumar and Amarendra K. Sarma, “Modulating dual-band electromagnetically induced transparency in a terahertz metamaterial”. International Conference on Fiber Optics and Photonics (Photonics 2018). December, 12-15, 2018 in IIT Delhi.
    31. S Jagan Mohan Rao, Maidul Islam, Gagan Kumar, Bishnu P Pal, Dibakar Roy Chowdhury, “Single split gap resonator based terahertz metamaterials for refractive index sensing" Proceedings Volume 10531, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XI; 105311K (2018); doi: 10.1117/12.2287320 Event: SPIE OPTO, 2018, San Francisco, California, United States on January 27-February 1, 2018.
    32. Maidul Islam, Dibakar Roy Chowdhury, and Gagan Kumar, “Planar Plasmonic Terahertz Waveguides for Sensor Applications.”, ICOLS 2018: 20th International Conference on Optics, Lasers and Spectroscopy, held in Zurich on Jan. 15-16, 2018. Best Paper Award.
    33. Koijam Monika Devi, Maidul Islam, Dibakar Roy Chowdhury, Amarendra K. Sarma and Gagan Kumar, “Exploring plasmon induced transparency in graphene based terahertz metamaterials.”, Mahindra Ecole Centrale, Hyderabad. IEEE Workshop on Recent Advances in Photonics Dec. 18-19, 2017.
    34. S Jagan Mohan Rao, Rakesh Sarkar, Divyam Khandelwal, Gagan Kumar and Dibakar Roy Chowdhury, “Studying the near field capacitive coupling in planar terahertz metamaterial.”, Mahindra Ecole Centrale, Hyderabad. IEEE Workshop on Recent Advances in Photonics. Dec. 18-19, 2017.
    35. Maidul Islam, K M Dhriti, Dibakar Roy Chowdhury, and Gagan Kumar, “Thin film sensing in terahertz plasmonic waveguide.”, Mahindra Ecole Centrale, Hyderabad. IEEE Workshop on Recent Advances in Photonics. Dec. 18-19, 2017.
    36. Sukhdeep Kaur, Manpreet Kaur, Roopkiranpreet Kaur, and Gagan Kumar, “Simulation of terahertz multimode propagation in parallel plate waveguide of metal.”, Mahindra Ecole Centrale, Hyderabad. IEEE Workshop on Recent Advances in Photonics. Dec. 18-19, 2017.
    37. Maidul Islam, Dibakar Roy Chowdhury and Gagan Kumar, “Terahertz guided mode propagation in a planar plasmonic waveguide and slow light properties.”, IIT Kanpur, Kanpur. International conference Photonics-2016 to be held in Dec. 2016 at IIT Kanpur, India.
    38. Koijam Monika Devi, Gagan Kumar, and Amarendra K. Sarma, “Surface Plasmon Polariton Akhmediev Breather in a dielectric-metal-dielectric multilayer structure.”, IIT Kanpur, Kanpur. International conference Photonics-2016 to be held in Dec. 2016 at IIT Kanpur, India.
    39. Deepak Kumar, S. Jagan Mohan Rao, Gagan Kumar, and Dibakar Roy Chowdhury, “Modulating the Fundamental Resonances in Near Field Coupled Planar Terahertz Metamaterials.”, IIT Kanpur, Kanpur. International conference Photonics-2016 to be held in Dec. 2016 at IIT Kanpur, India.
    40. Koijam Monika Devi, Amarendra K. Sarma and Gagan Kumar, “Enhanced terahertz transmission through a periodic array of tapered rectangular apertures.” 16th IUPAP Conference on Computational Physics (CCP) on Dec 2-5, 2015, IIT Guwahati, India. Proc. Journal of Physics: Conference Series (JPCS). 2016.
    41. Maidul Islam and Gagan Kumar, “Terahertz surface plasmon polaritons propagation in slanted pillar geometries.”, 16th IUPAP Conference on Computational Physics (CCP) on Dec 2-5, 2015, IIT Guwahati, India. Proc. Journal of Physics: Conference Series (JPCS). 2016.
    42. Sukhdeep Kaur, Sarabjeet Kaur, Manpreet Kaur and Gagan Kumar, “Numerical analysis of terahertz surface plasmon polaritons propagating in a parallel plate configuration .”, 16th IUPAP Conference on Computational Physics (CCP) on Dec 2-5, 2015, IIT Guwahati, India. Proc. Journal of Physics: Conference Series (JPCS). 2016.
    43. Deepak Kumar, S. Jagan Mohan Rao, Gagan Kuma, and Dibakar Roy Chowdhury, “Engineering the Resonances in Coupled Bilayer Terahertz Metamaterials.”, 4th International Conference on Nanoscience and Nanotechnology (ICONN-2017) to be held at SRM University . Aug 9-11, 2017. (Accepted).
    44. Jyoti Thakur, Deepak Kumar, Gagan Kumar and Manish K. Kashyap, “Search of magnetism in Mn-doped Silicene; A DFT approach”. Proc. National Conference on Physics of Engineering Materials (NCPEM-2016) in Deenbandhu Chhotu Ram University of Science & Technology, Murthal, Haryana. March 10-11, 2016.
    45. Gagan Kumar, “Engineering terahertz propagation properties using plasmonic metamaterials on silicon”. Proc. 12th International Conference on Fiber Optics and Photonics (Photonics 2014) at IIT Kharagpur, India. Dec. 13-16, 2014
    46. S. Li, Gagan Kumar, T. E. Murphy “Terahertz Absorption Saturation in Intrinsic Silicon Dielectric Ridge Waveguides”, Conference on Lasers and Electro-optics (CLEO), San Jose, CA (USA) STh3F.3 (2014).
    47. Gagan Kumar, S. Li, M. M. Jadidi, T. E. Murphy, “Anisotropically Etched Silicon Surfaces for Planar Plasmonic Terahertz Guided Wave Devices”, CLEO: Applications and Technology San Jose, California United States June 8-13, 2014 JW2A.97 (2014).
    48. Mohammad Jadidi, Gagan Kumar, Shanshan Li, Thomas Murphy, “Terahertz plasmonic waveguide based on periodically structured silicon surface”. Proc. Conference on Laser and Electro-Optics Sampling (CLEO) 2013, San Jose June 9-14, California.
    49. Gagan Kumar, Albert Cui and Ajay Nahata, “Terahertz Guided-Wave Devices using periodically patterned dimple structures,” Proc. Conference on Lasers and Electro-Optics Sampling (CLEO), May 16-21, 2010.
    50. M. J. Hagmann, Gagan Kumar, Ajay Nahata, “Analysis and Simulation of Generating Terahertz Surface Waves on a Tapered Field Emission Tip” Proc. 23rd International Vacuum Nanoelectronics Conference, Palo Alto, California July 26-30, 2010.
    51. T.D. Nguyen, S. Liu, Gagan Kumar, A. Nahata and Z.V. Vardeny, “THz Time domain Spectroscopy Studies of Graphite films and perforated graphite hole array” APS March meeting March 15-19, 2010, Portland, OR.

    Book Chapters/Thesis 

      1. Gagan Kumar and Prashant K. Sarswat, “Interaction of surface plasmon polaritons with nanomaterials.”,Reviews of Plasmonics. pp. 103-129 (2015).
      2. Gagan Kumar, “ The interaction of surface plasma waves with electron beams and nanoparticle.”, Ph.D. Thesis, submitted at IIT Delhi 2008.

      Invited Talks / Lectures 

        1. Gagan Kumar, “Terahertz plasmonics” Indo-French Conference on Frontiers in Photonics and Metamaterials (IFCFPM)-2023 organized by Mahindra University – Ecole Centrale School of Engineering (India) and Ecole centrale group of institutions (France), Hyderabad, India from April 20-22, 2023.
        2. Gagan Kumar, “Metamaterials for terahertz photonics” JIIT Student Chapter conference on Optics and Phtonics (JSCOP-2023) on April 12, 2022 in the Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida, UP.
        3. Gagan Kumar, “Toroidal excitations in planar terahertz meta-surfaces and applications”. XLV Symposium of Optical Society of India – Conference on Optics, Photonics & Quantum Optics – COPaQ 2022 on November 11, 2022.
        4. Gagan Kumar, “Terahertz Plasmonic and Metamaterial Devices”, INUP workshop at IIT Guwahati on March 2, 2022.
        5. Gagan Kumar, “Frontiers in Terahertz Plasmonic” 19th Refresher Course in Physical Sciences & Nano Sciences at UGC-Human Resource Development Centre, Jawaharlal Nehru University, New Delhi from January 11, 2022.
        6. Gagan Kumar, “Terahertz Plasmonic waveguide for applications in sensors and modulator” in the conference Frontiers in Terahertz Technologies and Applications (FTTA-2021) at CSIR – National Physical Laboratory during 09-11 December, 2021.
        7. Gagan Kumar, “Plasmonic Waveguides at Terahertz Frequencies” A Twin International Workshop (online) to discuss the experiments with THz radiation & electron beam in the field of Mat. Sc. & Bio. Sc. Inter University Accelerator Centre, New Delhi, June 25, 2021
        8. Gagan Kumar, “Terahertz plasmonic Guided Wave Devices”. Faculty Development Program (FDP) on “Recent Trends in Photonics” in the Department of Electronics and Communication Engineering, The Oxford College of Engineering on June 15, 2021.
        9. Gagan Kumar, “Terahertz plasmonic waveguides”. Faculty Development Program (FDP) on Photonics: Fundamentals and Applications” at the Samrat Ashok Technological Institute, Vidisha (M.P.), India from June 28-July 2, 2021.
        10. Gagan Kumar, “Plasmonics” Faculty Training Program (FTP) on Recent Trends in Physics of Engineering Materials at Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat, India June 9, 2021.
        11. Gagan Kumar, “Terahertz Technology: Challenges and Opportunities” TEQIP III International Conference on Aatmnirbhar Bharat: Technological Transformation and Preparedness in the Post-COVID World at Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat, India March 22-23, 2021.
        12. Gagan Kumar, “Terahertz Plasmonics” JIIT Student conference on Optics and Photonics (JSCOP) 2021, Department of Physics and Materials & Engineering, JIIT Noida March 13, 2021 (online, Zoom).
        13. Gagan Kumar, “Terahertz Photonics”. TEQIP sponsored short Term Course on "Recent Advances in RF and Photonics" February 22-26, 2021. IIT Guwahati.
        14. Gagan Kumar, QIP Short Term Course on "Spectroscopy and Characterization of New Generation Materials" December 14, 2020. IIT Roorkee.
        15. Gagan Kumar, “Terahertz plasmonic waveguides” Faculty Development Programme on the ‘Recent Advances in Photonics and Communications’ from November 2-6, 2020 in the Department of Physics at Guru Jambheshwar University of Science and Technology, Hisar.
        16. Gagan Kumar, “Terahertz Technology: Challenges and Opportunities” Plenary talk in webinar organized by Department of Physics and Chemistry at the Rajiv Gandhi University, Arunachal Pradesh on June 10, 2020. (via Zoom)
        17. Gagan Kumar, “Terahertz Plasmonics” In the webinar series organized by the Royal School of Applied and Pure Sciences at the Royal Global University, Guwahati on June 8, 2020. (via WebEx)
        18. Gagan Kumar, “Terahertz Plasmonics”, Special lecture for M.Sc. students involved in Carrier Advancement Bootcamp (CAB) in the Department of Physics, Kurukshetra University, Kurukshetra on May 27, 2020. (via Google meet)
        19. Gagan Kumar, “Terahertz Plasmonics”, Webinar (e-Conference) on “Prospective of Interdisciplinary Research in Science and Technology in the Present Scenario” at CCSU, Meerut, U.P. on May 15-16, 2020. (via Zoom)
        20. Gagan Kumar, "Plasmonic", Special lectures to Ph.D. students via web on May 06, 2020. Department of Physics, IIT Guwahati.
        21. Gagan Kumar, “Terahertz Plasmonics”, in Symposium “Recent Trends in Basic Plasma Research” at the Center of Plasma Physics, Institute for Plasma Research (CPP-IPR), Sonapur, Guwahati, on March 8, 2019.
        22. Gagan Kumar, “Electromagnetically Induced Transparency in Terahertz Metamaterials”, in Faculty Development Program on “Recent Advanced in Photonics”. International conference on “Photonics, Metamaterials and Plasmonics” Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida on February 14-16, 2019.
        23. Gagan Kumar, “Terahertz Plasmonics”, in Faculty Development Program on “Recent Advanced in Photonics” in Jorhat Engineering College from December 3-9, 2018.
        24. Gagan Kumar, “Terahertz Plasmonics”, in 33rd National Symposium on Plasma Science & Technology (PLASMA 2018) in Department of Physics & Astrophysics, Delhi University from December 4-7, 2018.
        25. Gagan Kumar, “Terahertz Plasmonics and Metamaterials”, in Faculty Development Program on “Recent Trends in Optics and Plasma Physics” at the Department of Physics and Material Science and Engineering, Jaypee Institute of Information Technology, Sec-62, Noida during 5-11 July 2018.
        26. Gagan Kumar, “Terahertz Plasmonics”, in ‘Focused Intensive Physics Camp for BSc Students’ to be organized during 11-22 June 2018 under PMMMNMTT, IIT Guwahati.
        27. Gagan Kumar, “Polarization of Light”, Teacher’s Training Program under the Pandit Madan Mohan Malaviya National Mission On Teachers and Teaching (PMMMNMTT) on May 15, 2018 in the Department of Physics at IIT Guwahati.
        28. Gagan Kumar, “Terahertz Plasmonic and Metamaterials Devices”, QIP Short Term Course on “Industrial Applications of Terahertz Radiation”. March 27th to April 2nd, 2017. Department of Physics, IIT Kharagpur, Kharagpur-721302, India.
        29. Gagan Kumar, “THz Photonics”, TEQIP Short Term Course on “Advances in Photonics”, Feb. 25-26, 2016. Department of Electrical and Communication Engineering, IIT Guwahati, Guwahati, Assam-781039, India.
        30. Gagan Kumar, “Planar Plasmonic Terahertz Waveguides”. International Conference on High Power Coherent Radiation Generation and Its Interaction With Matter, Feb. 12-14, 2016, Vidisha (M.P.), India.
        31. Gagan Kumar, “Terahertz guided wave devices using plasmonic metamaterials”. 16th IUPAP Conference on Computational Physics (CCP) on Dec 2-5, 2015, IIT Guwahati, Assam, India.
        32. Gagan Kumar, “Significance of ultrashort pulses for terahertz generation and detection”. Talk in the seminar series celebrating International Year of Light, Sept. 29, 2015.
        33. Gagan Kumar, “Terahertz plasmonic metamaterials”. on April 10, 2015 in the short term course on Fundamentals and Applications of Metamaterials – 2015 at IIT Kanpur, Kanpur, India
        34. Gagan Kumar, “Terahertz Photonics”, Department of Physics, Indian Institute of Technology (IIT) Kanpur, India on April 10, 2015.
        35. Gagan Kumar “Terahertz plasmonics” on Jan. 3, 2015 in the Department of Physics, IIT Guwahati, Guwahati-781039, India.
        36. Gagan Kumar “Terahertz Science and Applications”, in the Department of Physics, Kurukshetra University Kurukshetra on Feb. 10, 2015.
        37. Gagan Kumar “Terahertz plasmonic waveguides” The 12th International Conference on Fiber Optics and Photonics (Photonics 2014), Dec. 13-16, IIT Kharagpur, India.
        38. Gagan Kumar “Planar Plasmonic THz Waveguides Using Thin Structured Metal Films” in the Center for Applied Electromagnetic at the University of Maryland, Nov. 2, 2010.

        Miscellaneous

        1. Tanmay Bhowmik, Bhairov Kr. Bhowmik, Pranav Kr. Pandey, Gagan Kumar, Debabrata Sikdar, "Epsilon-Near-Zero Material based Dual-Polarization On-Chip Electro-Optic Modulator" International conference on Information Technology and Nanotechnology (ITNT-2023), April 17-21, 2023 Samara, Russia.
        2. Bhagwat Singh Chouhan, Km Dhriti, Ashish Kumar Chowdhary, Debabrata Sikdar and Gagan Kumar, “Modulating broadband Terahertz in a Graphene assisted dielectric Metamaterial” IEEE WRAP 2022, IIT Bombay March 4-6, 2022 - Best Student Poser Award to Mr. Bhagwat Singh
        3. Angana Bhattacharya, Gagan Kumar, “A Terahertz Metamaterial Sensor based on toroidal multiband transparency”, Research Conclave at IIT Guwahati on Jan 21, 2022 (oral). -Best Oral Presentation Award (Ms. Angana)
        4. Bhairav Kumar Bhowmik, Gagan Kumar, “Exploring Thin Film Sensing using Meta-Waveguide Design”, Research Conclave at IIT Guwahati on Jan 21, 2022 (oral).
        5. Bhagwat Singh Chauhan, Gagan Kumar, “Polarization Insensitive Graphene-Dielectric based Tunable Terahertz Absorption Modulator”, Research Conclave at IIT Guwahati on Jan 21, 2022 (oral).
        6. Angana Bhattacharya, Rakesh Sarkar, Gagan Kumar, “Single band EIT in toroidal terahertz metamaterials”, in the conference Frontiers in Terahertz Technologies and Applications (FTTA-2021) at CSIR – National Physical Laboratory during 09-11 December, 2021. (Contributory talk by Angana)
        7. Bhairov Kumar Bhowmik, Maidul Islam, Dhriti Maurya, Gagan Kumar “Exploring sensing capabilities in terahertz meta-waveguide-based approach” in the conference Frontiers in Terahertz Technologies and Applications (FTTA-2021) at CSIR – National Physical Laboratory during 09-11 December, 2021. -Best Poser Award
        8. Bhagwat Singh Chouhan, Dhriti Maurya, D. Sikdar, Gagan Kumar “Polarisation insensitive Graphene –Dielectric Based tunable terahertz absorption modulator” in the conference Frontiers in Terahertz Technologies and Applications (FTTA-2021) at CSIR – National Physical Laboratory during 09-11 December, 2021. -Best Poser Award
        9. S. Jagan Mohan Rao, Gagan Kumar, Abul K. Azad, and Dibakar Roy Chowdhury, “Studying ultrafast switching in single split ring resonator based THz metamaterials through ion implanted silicon placed in the gap of a resonator” OSI - International Symposium on Optics (OSI-ISO 2018) in IIT Kanpur. September 19 – 22, 2018. (Submitted).
        10. Maidul Islam, Dibakar Roy Chowdhury, Gagan Kumar, "Planar Plasmonic Terahertz Waveguides for Sensor Applications", ICOLS 2018: 20th International Conference on Optics, Lasers and Spectroscopy, held in Zurich on Jan. 15-16, 2018. -Best Paper Award
        11. K. M. Devi, M. Islam, D. R. Chowdhury, A. K. Sarma and Gagan Kumar “Exploring plasmon induced transparency in graphene based terahertz metamaterials”, ICOP 2017: International Conference on Optics and Photonics, to be held on Nov 09-10, 2017, in Singapore, SG.
        12. SJM Rao, M. Islam, Gagan Kumar and D. R. Chowdhury, “Numerical Study of Resonance modes in Terahertz Metamaterials for thin film sensing perspective”. Presented in SPIE Photonic West 2018 held from January 27-February 1, 2018 at The Moscone Center San Francisco, California, United States.
        13. S Jagan Mohan Rao, Gagan Kumar and Dibakar Roy Chowdhury, “Tuning near field capacitive coupling in planar terahertz metamaterials”. Presented in SPIE Photonic West 2018 held from January 27-February 1, 2018 at The Moscone Center San Francisco, California, United States.
        14. S. Jagan Mohan Rao1, Maidul Islam, Gagan Kumar , Bishnu P. Pal and Dibakar Roy Chowdhury, “Resonance Mode Study in Planar Terahertz Metamaterials Towards Thin Film Sensing Perspective”. Poster presented in ‘International Conference on Advances in Optics and Photonics (ICAOP 2017)’ at Guru Jambheshwar University of Science and Technology Hisar, Haryana held on Nov. 23-26, 2017.
        15. S Jagan Mohan Rao, Deepak Kumar, Gagan Kumar, Dibakar Roy Chowdhury, “Effect of resonator displacements in near field coupled terahertz metamaterials” Third Regional Conference on Radio Science 2017 which will be held during 1 - 4 March, 2017 at the world famous town Tirupati, Andhra Pradesh, India.
        16. Maidul Islam, K M Dhriti, Dibakar Roy Chowdhury, and Gagan Kumar, “Thin Film Sensing in Terahertz Plasmonic Waveguide”. Poster presented in IEEE Workshop on Recent Advances in Photonics, Dec. 18-19, 2017, Mahindra Ecole Centrale, Hyderabad.
        17. K. M. Devi, M. Islam, D. R. Chowdhury, A. K. Sarma and Gagan Kumar “Exploring plasmon induced transparency in graphene based terahertz metamaterials”. Poster presented in IEEE Workshop on Recent Advances in Photonics, Dec. 18-19, 2017, Mahindra Ecole Centrale, Hyderabad.
        18. SJM Rao, R. Sarkar, D. Khandelwal, Shahjahan, Gagan Kumar, D. R. Chowdhury, “Studying the near field capacitive coupling in planar terahertz metamaterial”. Poster presented in IEEE Workshop on Recent Advances in Photonics, Dec. 18-19, 2017, Mahindra Ecole Centrale, Hyderabad.
        19. Dibakar Roy Chowdhury, S Jagan Mohan Rao, and Gagan Kumar, “Analyzing the near field electromagnetic coupling in terahertz metamaterials”. Presented in ‘International Conference on Advances in Optics and Photonics (ICAOP 2017)’ at Guru Jambheshwar University of Science and Technology Hisar, Haryana held on Nov. 23-26, 2017.
        20. S Jagan Mohan Ra, Gagan Kumar, Dibakar Roy Chowdhury, “Exploring the near field inductive coupling in broadside coupled terahertz metamaterials.” Poster presented in ‘International Conference on Advances in Optics and Photonics (ICAOP 2017)’ at Guru Jambheshwar University of Science and Technology Hisar, Haryana held on Nov. 23-26, 2017.
        21. Deepak Kumar, S. Jagan Mohan Rao, Ranjan Kumar, Gagan Kumar and Dibakar Roy Chowdhury, “Electromagnetic Resonances in Coupled Metamaterials”, Poster presented in ‘International Conference on Advances in Optics and Photonics (ICAOP 2017)’ at Guru Jambheshwar University of Science and Technology Hisar, Haryana held on Nov. 23-26, 2017.
        22. Gagan Kumar, Koijam Monika Devi, Amarendra K. Sarma and Dibakar Roy Chowdhury, “Modulating Plasmon Induced Transparency in Terahertz Metamaterials”. Presented in ICOP 2017: 19th International Conference on Optics and Photonics held in Singapore, SG on November, 9-10, 2017.
        23. Maidul Islam and Gagan Kumar, “Terahertz surface plasmon polaritons propagation in slanted pillar geometries.” 16th IUPAP Conference on Computational Physics (CCP) on Dec 2-5, 2015, IIT Guwahati, Assam, India.
        24. Koijam Monika Devi, Amarendra K. Sarma and Gagan Kumar, “Enhanced terahertz transmission through a periodic array of tapered rectangular apertures.” 16th IUPAP Conference on Computational Physics (CCP) on Dec 2-5, 2015, IIT Guwahati, Assam, India.
        25. D. Bhattacharyya, P. K. Sarswat, Maidul Islam, Gagan Kumar, Mano Misra, and Michael L. Free, “Optical and surface plasmon resonance behaviour of Au and Ag coated TiO2 nanotube arrays,” Int’l Year of Light Symposium, Oct. 31, 2015 in the Department of Physics at IIT Guwahati.
        26. Gagan Kumar, “Terahertz Plasmonic Waveguides”, Department of Physics, Indian Institute of Technology (IIT) Kanpur, India on April 10, 2015.
        27. Gagan Kumar, “Terahertz Plasmonic Metamaterials and Guided Wave Devices”, Department of Physics, Indian Institute of Technology (IIT) Delhi, India on Oct. 21, 2015
        28. Gagan Kumar, “Terahertz Plasmonic Metamaterials”, Department of Physics, Indian Institute of Technology (IIT) Ropar, India on Feb. 13, 2015
        29. Gagan Kumar, “Terahertz Photonics”, Department of Physics, Indian Institute of Science Education and Research (IISER) Mohali, India on Feb. 9, 2015.
        30. Gagan Kumar, Shanshan Li, Thomas E. Murphy, “Plasmonic Terahertz Waveguide Based on Pyramidal Troughs Etched in Silicon”. The 5th International conference on Metamaterials, Photonic Crystals and Plasmonics (META’14) at Nanyang Technological University (NTU) Singapore. May 20-23, 2014.
        31. Gagan Kumar “Plasmonics and Nanoporous materials - devices and applications”, Department of Physics, University of Chicago, USA on April 19, 2013.
        32. Gagan Kumar “Terahertz plasmonic metamaterials” Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam on May 27, 2013.
        33. Mohammad Jadidi, Gagan Kumar, Shanshan Li, Thomas Murphy, “Terahertz plasmonic waveguide based on periodically structured silicon surface”. CLEO 2013, San Jose June 9-14, California.
        34. S. Liu, T. Nguyen, Gagan Kumar, Z. Valy Vardeny and Ajay Nahata, “Terahertz plasmonic properties of Carben-based materials”, International workshop on Optical Terahertz Science and Technology (OTST), Kyoto Terrsa, Japan, April 1-5, 2013.
        35. Gagan Kumar, Shashank Pandey and Ajay Nahata, “Planar Terahertz Waveguides Based on Complementary Split Ring Resonators,” International workshop on Optical Terahertz Science and Technology (OTST), Santa Barbara, CA, March 13-17, 2011.
        36. Shashank Pandey, Gagan Kumar and Ajay Nahata, “Slot Waveguide-Based Splitters for Broadband Terahertz Radiation”, International workshop on Optical Terahertz Science and Technology (OTST), Santa Barbara, CA, March 13-17, 2011.
        37. M. J. Hagmann, Gagan Kumar, S. Pandey and A. Nahata, “Analysis and simulation of generating terahertz surface waves in laser assisted field emission”, Bulletin of the American Physical Society, vol. 56, no. 1, March 21-25, 2011, Dallas, Texas.
        38. Gagan Kumar, Albert Cui and Ajay Nahata, “Terahertz Guided-Wave Devices using periodically patterned dimple structures,” International Conference on lasers and electro-optics sampling (CLEO), May 16-21, 2010.
        39. Gagan Kumar, W. Zhu, A. Cui and A. Nahata, “Planar terahertz guided-wave devices using plasmonic metamaterials,” International Conference on Metamaterials, Photonic Crystals and Plasmonics (META'10) – Cairo, Egypt (2010). Presented, February 2010.
        40. Gagan Kumar, W. Zhu, A. Cui and A. Nahata, “Using plasmonic metamaterials to create terahertz guided-wave circuits,” 13th European Microwave Week 2010– Paris, France (2010). Presented, June 2010.
        41. Gagan Kumar and V. K. Tripathi, “Excitation of surface plasma wave over a plasma cylinder by a relativistic electron beam via Cerenkov interaction”, Bulletin of the American Physical Society 53, 2008 at the 50th Annual Meeting of the Division of Plasma Physics, Nov. 17-20, 2008, Dallas, Texas.
        42. Gagan Kumar, C. S. Liu and V. K. Tripathi “Electron acceleration by surface plasma waves on a metal surface” in ‘Summer College on Plasma Physics-New Developments 2007’ held on 30 July - 24 August 2007 in Abdus Salam International Center for Theoretical Physics (ICTP) – Trieste, Italy
        43. Gagan Kumar and V. K. Tripathi, “Modeling of SERS Sensor in an attenuated total reflection (ATR) configuration”, 21st National Symposium on Plasma Science and Technology, MNIT Jaipur, India, Dec. 19-23, 2006.
        44. Gagan Kumar and V. K. Tripathi, “Laser mode conversion into a surface plasma wave”, Proc. 20th National Symposium on Plasma Science and Technology, CUSAT, Cochin, India, Dec. 5-7, 2005.