Publications

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Full publication list and citation summary available at the Google Scholar webpage.

Highly Cited Papers (designated by Web of Science)
Journal Articles
  1. Demas, M. Hary, G. Genty, S. Ramachandran, “Optimization and realignment of OAM mode excitation in ring-core optical fibers using machine learning,” Optics Letters 49, 5003 (2024).
  2. D. I. Shahar, H. B. Kabagöz, S. Ramachandran “Generation of spatial combs digitized by orbital angular momentum,” APL Photonics 1 January 2024; 9 (1): 016113.
  3. Wang, J. Ai, Z. Ma, S. Ramachandran, J. Wang, “Finding the superior mode basis for mode-division multiplexing: a comparison of spatial modes in air-core fiber,” Advanced Photonics 5, 056003 (2023).
  4. Liang, H. Wang, X. Zhang, J. Ai, Z. Ma, S Ramachandran, J. Wang, “Reconfigurable structured light generation and its coupling to air-core fiber,” Adv. Photon. Nexus 2, 036015 (2023)
  5. Z. Ma, P. Kristensen and S. Ramachandran, “Scaling information pathways in optical fibers by topological confinement,” Science 380, 278-282 (2023).
  6. A.D. White, L. Su, D.I. Shahar, K.Y. Yang, G.Ho Ahn, J.L. Skarda, S. Ramachandran, J. Vučković, “Inverse Design of Optical Vortex Beam Emitters,” ACS Photonics doi: 10.1021/acsphotonics.2c01007 (2022).
  7. Z. Wan, Y. Liang, X. Zhang, Z. Tang, L. Fang, Z. Ma, S. Ramachandran, J. Wang, “Remote measurement of the angular velocity vector based on vectorial Doppler effect using air-core optical fiber,” Research 2022, 9839502.
  8. S. Ramachandran, “3D-printing yields structured light,” Invited Paper, Nat. Photon. 16, 618 (2022).
  9. A. P. Greenberg, Z. Ma, and S. Ramachandran, “Angular momentum driven dynamics of stimulated Brillouin scattering in multimode fibers,” Opt. Express 30, 29708-29721 (2022)
  10. I. Cristiani et al, “Roadmap on multimode photonics,” Invited Paper, Opt. 24, 083001 (2022).
  11. X. Liu, Z. Ma, A. Antikainen, S. Ramachandran, “Raman gain control in optical fibers with orbital-angular-momentum-induced chirality of light,” Opt. Express 30, 26967-26974 (2022)
  12. L. Rishøj, I.C. Hernández, S. Ramachandran, N. Jowett, “Multiphoton microscopy for label-free multicolor imaging of peripheral nerve,” Journal of Biomedical Optics 27, 056501 (2022).
  13. A. Forbes, S. Ramachandran, and Q. Zhan, “Photonic angular momentum: progress and perspectives,” Invited Paper, Nanophotonics 11, 625 (2022).
  14. H. B. Kabagöz, A. Antikainen, and S. Ramachandran, “Passive, controllable generation of energetic multi-color pulses via spatial mode re-organizations in optical fibers,” APL Photonics 6, 126109 (2021).
  15. D-R. Song, Lu Yan, Tao He, and Siddharth Ramachandran, “Integrated orbital angular momentum mode generator with wide spectral tunability,” Invited Paper, Opt. Soc. Am. B 38, F186 (2021)
  16. R. Lindberg, X. Liu, A. Zukauskas, S. Ramachandran and V. Pasiskevicius, “Simultaneous nonlinear wavelength and mode conversion for high-brightness blue sources,” J. Opt. Soc. Am. B 38, 3491 (2021)
  17. H. B. Kabagöz, A. Antikainen, and S. Ramachandran, “Converting noise into solitons: optical self-organization through intermodal nonlinearity,” Opt. Express 29, 18315-18324 (2021)
  18. Z. Ma and S. Ramachandran, “Propagation stability in optical fibers: role of path memory and angular momentum,” Invited Paper, Nanophotonics 10, 209 (2021).
  19. A. P. Greenberg, G. Prabhakar, and S. Ramachandran, “High resolution spectral metrology leveraging topologically enhanced optical activity in fibers,” Nature Communications 11, 5257 (2020).
  20. A. Antikainen, H B. Kabagöz, and S. Ramachandran, “Fragility of a soliton’s shot-to-shot coherence,” Opt. Lett. 45, 5393 (2020).
  21. M. Ordu, J. Guo, A.E. Akosman, S. Erramilli, S. Ramachandran and S.N. Basu, “Effect of Thermal Annealing on Mid-Infrared Transmission in Semiconductor Alloy-Core Glass-Cladded Fibers,” Adv. Fiber Mater. (2020).
  22. L. Rishøj, F. Deng, B. Tai, J-X. Cheng, and S. Ramachandran, “Jitter-free, dual-wavelength, ultrashort-pulse, energetic fiber sources using soliton self-mode conversion,” Opt. Express 28, 4333-4339 (2020)
  23. X. Liu, E.N. Christensen, K. Rottwitt and S. Ramachandran, “Nonlinear four-wave mixing with enhanced diversity and selectivity via spin and orbital angular momentum conservation,” APL Photonics 5, 010802 (2020).
  24. P. Gregg, P. Kristensen, A. Rubano, S. Golowich, L. Marrucci and S. Ramachandran, “Enhanced Spin Orbit Interaction of Light in Highly Confining Optical Fibers for Mode Division Multiplexing,” Nature Communications 10, 4707 (2019).
  25. S. D. Johnson, Z. Ma, M. Padgett and S. Ramachandran, “Measurement of the spin-orbit coupling interaction in ring-core optical fibers,” OSA Continuum 2, 2976 (2019).
  26. D. Cozzolino, D. Bacco, B.D. Lio, K. Ingerslev, Y. Ding, K. Dalgaard, P. Kristensen, M. Galili, K. Rottwitt, S. Ramachandran, L.K. Oxenløwe, “Orbital Angular Momentum States Enabling Fiber-based High-dimensional Quantum Communication,” Phys. Rev. Applied 11, 064058 (2019).
  27. F. Pang, H. Zheng, H. Liu, J. Yang, N. Chen, Y. Shang, S. Ramachandran and T. Wang, “The orbital angular momentum fiber modes for magnetic field sensing,” IEEE Photon. Tech. Lett. 31, 893 (2019).
  28. G. Prabhakar, P. Gregg, L. Rishoj, P. Kristensen, and S. Ramachandran, “Octave-wide supercontinuum generation of light-carrying orbital angular momentum,” Opt. Express 27, 11547-11556 (2019).
  29. S. D. Johnson, D.B. Phillips, Z. Ma, S. Ramachandran and M.J. Padgett, “A light-in-flight single-pixel camera for use in the visible and short-wave infrared,” Opt. Express 27, 9829-9837 (2019)
  30. V. Balaswamy, Siddharth Ramachandran, and V. R. Supradeepa, “High-power, cascaded random Raman fiber laser with near complete conversion over wide wavelength and power tuning,” Opt. Express 27, 9725-9732 (2019).
  31. L. Rishøj, B. Tai, P. Kristensen, and S. Ramachandran, “Soliton self-mode conversion: revisiting Raman scattering of ultrashort pulses,” Optica 6, 304-308 (2019).
  32. A. Antikainen, L. Rishøj, B. Tai, S. Ramachandran, and G. P. Agrawal, “Fate of a Soliton in a High Order Spatial Mode of a Multimode Fiber,” Phys. Rev. Lett. 122, 023901 (2019).
  33. V. Balaswamy, S. Aparanji, S. Arun, S. Ramachandran and V.R. Supradeepa, “High-power, widely wavelength tunable, grating-free Raman fiber laser based on filtered feedback,” Optics Letters 44, 279-282 (2019).
  34. L. Yan, P. Kristensen, S. Ramachandran, “Vortex fibers for stimulated emission depletion (STED) microscopy,” APL Photonics 4, 022903 (2019).
  35. J. Demas, L. Rishøj, X. Liu, G. Prabhakar, S. Ramachandran, “Intermodal group-velocity engineering for broadband nonlinear optics,” Photon. Res. 7, 1-7 (2019)
  36. A.B. Bandara, Z. Zuo, K. McCutcheon, S. Ramachandran, J.R. Heflin, T.J. Inzana, “Identification of Histophilus somni by a nanomaterial optical fiber biosensor assay,” J. Veterinary Diagnostic Investigation, 1-9 (2018).
  37. S. Zhu, S. Pidishety, Y. Feng, S. Hong, J. Demas, R. Sidharthan, S. Yoo, S. Ramachandran, B. Srinivasan, J. Nilsson, “Multimode-pumped Raman amplification of a higher order mode in a large mode area fiber,” Opt. Express 26, 23295-23304 (2018).
  38. A. Sit, R. Fickler, F. Alsaiari, F. Bouchard, H. Larocque, P. Gregg, L. Yan, R.W. Boyd, S. Ramachandran, E. Karimi, “Quantum cryptography with structured photons through a vortex fiber,” Opt. Lett. 43, 4108-4111 (2018).
  39. K. Ingerslev, P. Gregg, M. Galili, F. Da Ros, H. Hu, F. Bao, M.A. Usuga Castaneda, P. Kristensen, A. Rubano, L. Marrucci, K. Rottwitt, T. Morioka, S. Ramachandran, and L.K. Oxenløwe, “12 mode, WDM, MIMO-free orbital angular momentum transmission,” Opt. Express 26, 20225 (2018)
  40. A. Gulistan, S. Ghosh, S. Ramachandran, and B.M.A. Rahman, “Efficient strategy to increase higher order inter-modal stability of a step index multimode fiber,” Opt. Express 25, 29714 (2017)
  41. S. Pidishety, S. Pachava, P. Gregg, S. Ramachandran, G. Brambilla, and B. Srinivasan, “Orbital angular momentum beam excitation using an all-fiber weakly fused mode selective coupler,” Opt. Lett. 42, 4347-4350 (2017).
  42. M. Ordu, J. Guo, G.Ng Pack, P. Shah, S. Ramachandran, M.K. Hong, L.D. Ziegler, S.N. Basu and S. Erramilli, “Nonlinear optics in germanium mid-infrared fiber material: Detuning oscillations in femtosecond mid-infrared spectroscopy,” AIP Advances 7, 095125 (2017).
  43. M. Ordu, J. Guo, B. Tai, M.K. Hong, S. Erramilli, S. Ramachandran and S.N. Basu, “Mid-infrared transmission through germanium-core borosilicate glass-clad semiconductor fibers,” Opt. Mater. Express 7, 3107-3115 (2017).
  44. T. He, J. Demas and S. Ramachandran, “Ultra-low loss dispersion control with chirped transmissive fiber gratings,” Opt. Lett. 42, 2531-2534 (2017).
  45. J. Demas, G. Prabhakar, T. He and S. Ramachandran, “Wavelength-agile high-power sources via four-wave mixing in higher-order fiber modes,” Opt. Exp. vol. 25, p. 7455, 2017.
  46. Y. Jung, Q. Kang, R. Sidharthan, D. Ho, S. Yoo, P.Gregg, S. Ramachandran, S. Alam, D.J. Richardson, “Optical OAM Amplifier Based on an Air-Hole Erbium-Doped Fiber,” J. Lightwave Tech. 35, 430 (2017).
  47. D.L.P. Vitullo, C.C. Leary, P. Gregg, R.A. Smith, D.V. Reddy, S. Ramachandran and M. G. Raymer, “Observation of Interaction of Spin and Intrinsic Orbital Angular Momentum of Light,” Phys. Rev. Lett. 118, 083601 (2017).
  48. P. Gregg, P. Kristensen, and S. Ramachandran, “13.4km OAM state propagation by recirculating fiber loop,” Opt. Express vol. 24, 18938 (2016).
  49. L. Rishøj, M. Jones, J. Demas, P. Gregg, G. Prabhakar, L. Yan, T. Hawkins, J. Ballato, and S. Ramachandran, “Polymer-clad silica fibers for tailoring modal area and dispersion,” Opt. Lett. 41, 3587-3590 (2016).
  50. B.N. Tugchin, N. Janunts, M. Steinert, K. Dietrich, D. Sivun, S. Ramachandran, K.V. Nerkararyan, A. Tünnermann, T. Pertsch, “Controlling the excitation of radially polarized conical plasmons in plasmonic tips in liquids,” RSC Advances, 6, 53273 (2016).
  51. J. Demas, L. Rishøj and S. Ramachandran, “Free-space beam shaping for precise control and conversion of modes in optical fiber,” Opt. Exp. vol. 23, p. 28531, 2015.
  52. Q. Kang, P. Gregg, Y. Jung, E.L. Lim, S. Alam, S. Ramachandran and D.J. Richardson, “Amplification of 12 OAM modes in air-core erbium doped fiber,” Opt. Exp. vol. 23, p. 28341, 2015.
  53. L. Yan, P. Gregg, E. Karimi, A. Rubano, L. Marrucci, R. Boyd and S. Ramachandran, “Q-plate enabled spectrally diverse orbital-angular-momentum conversion for STED microscopy,” Optica vol. 2, p. 900, 2015.
  54. A.B. Bandara, Z. Zuo, S. Ramachandran, A. Ritter, J.R. Heflin, T.J. Inzan, “Detection of methicillin-resistant staphylococci by biosensor assay consisting of nanoscale films on optical fiber long-period gratings,” Biosensors and Bioelectronics, vol. 70, p. 433, 2015.
  55. L. Yan, R. Barankov, P. Steinvurzel, and S. Ramachandran, “Modal-weight measurements with fiber gratings,” J. Lightwave Tech., vol. 33, p. 2784, 2015.
  56. P. Gregg, M. Mirhosseini, A. Rubano, L. Marrucci, E. Karimi, R.W. Boyd, and S. Ramachandran, “Q-plates as higher order polarization controllers for orbital angular momentum modes of fiber,”Optics Letters, vol. 40, p. 1729, 2015.
  57. A. E. Willner, H. Huang, Y. Yan, Y. Ren, N. Ahmed, G. Xie, C. Bao, L. Li, Y. Cao, Z. Zhao, J. Wang, M. P. J. Lavery, M. Tur, S. Ramachandran, A. F. Molisch, N. Ashrafi, and S. Ashrafi, “Optical communications using orbital angular momentum beams,” Invited Paper, Adv. Opt. Photon. vol. 7, p. 66, 2015.
  58. P. Gregg, P. Kristensen, and S. Ramachandran, “Conservation of orbital angular momentum in air-core optical fibers,” Optica vol. 2, p. 267, 2015.
  59. S. Ramachandran, P. Gregg, P. Kristensen, and S. E. Golowich, “On the scalability of ring fiber designs for OAM multiplexing,” Invited Paper, Opt. Exp. vol. 23, p. 3721, 2015.
  60. J. Demas, P. Steinvurzel, B. Tai, L. Rishøj, Y. Chen, and S. Ramachandran, “Intermodal nonlinear mixing with Bessel beams in optical fiber,” Optica vol. 2, p. 14, 2015.
  61. J. Demas and S. Ramachandran, “Sub-second mode measurement of fibers using C2 imaging,” Opt. Exp. vol. 22, p. 23043, 2014.
  62. A. Yurt, M.D.W. Grogan, S. Ramachandran, B.B. Goldberg, and M. Selim Ünlü, “Effect of vector asymmetry of radially polarized beams in solid immersion microscopy,” Opt. Exp. vol. 22, p. 7320, 2014.
  63. P. Steinvurzel, J. Demas, B. Tai, Y. Chen, L. Yan, and S. Ramachandran, “Broadband parametric wavelength conversion at 1  μm with large mode area fibers,” Optics Letters, vol. 39, p. 743, 2014.
  64. S. Ramachandran and P. Kristensen, “Optical vortices in fiber,”Invited Paper, J. Nanophotonics vol. 2, p. 455, 2013.
  65. L. Rishøj, P. Kristensen, S. Ramachandran and K. Rottwitt, “Experimental demonstration of intermodal nonlinear effects between full vectorial modes in a few moded fiber,” Opt. Exp. vol. 21, p. 28836, 2013.
  66. D.N. Schimpf, W. Putnam, M.D.W. Grogan, S. Ramachandran and F.X. Kärtner, “Radially polarized Bessel-Gauss beams: decentered Gaussian beam analysis and experimental verification,” Opt. Exp. vol. 21, p. 18469, 2013.
  67. N. Bozinovic, Y. Yue, Y. Ren, M. Tur, P. Kristensen, H Huang, A.E. Willner, and S. Ramachandran, “Terabit-Scale Orbital Angular Momentum Mode Division Multiplexing in Fibers,” Science vol. 340 (6140), p. 1545, 2013.
  68. M. Laurila, R. Barankov, M. Jørgensen, T. Alkeskjold, J. Broeng, J. Lægsgaard, S. Ramachandran, “Cross-correlated imaging of single-mode photonic crystal rod fiber with distributed mode filtering,” Opt. Exp. vol. 21, p 9215, 2013.
  69. S. Golowich, N. Bozinovic, P. Kristensen, and S. Ramachandran, “Complex mode amplitude measurement for a six-mode optical fiber,” Opt. Exp., vol. 21, p. 4931, 2013.
  70. J. Demas, M.D.W. Grogan, T. Alkeskjold, S. Ramachandran, “Sensing with optical vortices in photonic crystal fibers,”Optics Letters, vol. 37, p. 3768, 2012.
  71. Y. Chen, L. Yan, P. Steinvurzel, L. Rishoj, S. Ramachandran, “Dynamically tunable optical bottles from an optical fiber,” Optics Letters, vol. 37, p. 3327, 2012.
  72. R.A. Barankov, K. Wei, B. Samson and S. Ramachandran, “Resonant Bend Loss in Leakage Channel Fibers,” Optics Letters, vol. 37, p. 3147, 2012.
  73. D.N. Schimpf and S. Ramachandran, “Polarization-resolved imaging of an ensemble of waveguide modes,” Optics Letters, vol. 37, p. 3069, 2012.
  74. N. Bozinovic, S. Golowich, P. Kristensen, S. Ramachandran, “Control of orbital angular momentum of light, with optical fibers,” Optics Letters, vol. 37, p. 2451, 2012.
  75. P. Steinvurzel, K. Tantiwanichapan, M. Goto, and S. Ramachandran, “Fiber-based Bessel beams with controllable diffraction-resistant distance,” Optics Letters, vol. 36, p. 4671, 2011.
  76. D.N. Schimpf, R. A. Barankov and S. Ramachandran, “Cross-correlated (C2) imaging of fiber and waveguide modes,” Optics Express, vol. 19, p. 13008, 2011.
  77. S. Ramachandran, C. Smith, P. Kristensen, P. Balling, “Nonlinear generation of broadband polarisation vortices,” Optics Express, vol. 18, p. 23212, 2010.
  78. J.W. Nicholson, J.M. Fini, A.M. DeSantolo, E. Monberg, F. DiMarcello, J. Fleming, C. Headley, D.J. DiGiovanni, S. Ghalmi and S. Ramachandran, “A higher-order-mode Erbium-doped-fiber amplifier,” ,”Optics Express, vol. 18, p. 17651, 2010.
  79. S. Ramachandran, P. Kristensen and M.F. Yan, “Generation and propagation of radially polarized beams in optical fibers,” Optics Letters, vol. 34, p. 2525, 2009.
  80. Y.Z. Ma, Y. Sych, G. Onishchukov, S. Ramachandran, U. Peschel, B. Schmauss and G. Leuchs, “Fiber-modes and fiber-anisotropy characterization using low-coherence interferometry,” Appl. Phys. B, vol. 96, p. 345, 2009.
  81. Z. Wang, J.R. Heflin, K.V. Cott, R.H. Stolen, S. Ramachandran, S. Ghalmi, “Biosensors employing ionic self-assembled multilayers adsorbed on long-period fiber gratings,” Sensors and Actuators B, vol. 139, p. 618, 2009.
  82. R.S. Quimby, T.F. Morse, R.L. Shubochkin and S. Ramachandran, “Yb3+ ring doping in high-order-mode fiber for high-power 977-nm lasers and amplifiers,” IEEE J. Selected Topics Quant. Electron., vol. 15, p. 12, 2009.
  83. S. Ramachandran, “Ultra-large effective-area, higher-order mode fibers: a new strategy for high-power lasers,” Invited Paper, Laser & Photon. Rev., vol. 2, p. 429, Dec. 2008.
  84. J. W. Nicholson, A. D. Yablon, S. Ramachandran and S. Ghalmi, “Spatially and spectrally resolved imaging of modal content in large-mode-area fibers,” Optics Express, vol. 16, p. 7233, 2008.
  85. M. Sumetsky and S. Ramachandran, “Multiple mode conversion and beam shaping with superimposed long period gratings,” Optics Express, vol. 16, p. 402, 2008.
  86. T-J Ahn, Y. Park, D.J. Moss, S. Ramachandran and J. Azana, “Frequency-domain modal delay measurement for higher-order mode fiber based on stretched pulse interference,” Optics Lett., vol. 33, p. 19, 2008.
  87. M. D. Mermelstein, S. Ramachandran, J. M. Fini, S. Ghalmi, “SBS gain efficiency measurements and modeling in a 1714 mm2 effective area LP08 higher-order mode optical fiber,” Optics Express, vol. 15, p. 15952, 2007.
  88. M. Schultz, O. Prochnow, A. Ruehl, D. Wandt, D. Kracht, S. Ramachandran, and S. Ghalmi, “Sub 60 fs ytterbium-doped fiber laser with a fiber-based dispersion compensation,” Optics Lett., vol. 32, p. 2372, 2007.
  89. N. Lindlein, G. Leuchs and S. Ramachandran, “Achieving Gaussian outputs from large-mode-area higher-order-mode fibers,” Applied Optics, vol. 46, p. 5147, 2007.
  90. J.W. Nicholson, S. Ramachandran and S. Ghalmi, “A passively-modelocked, Yb-doped, figure-eight, fiber laser utilizing anomalous-dispersion higher-order-mode fiber,” Optics Exp, vol. 15, p. 6623, 2007.
  91. J.H. Lee, J.V. Howe, C. Xu, S. Ramachandran, S. Ghalmi and M.F. Yan, “Generation of femtosecond pulses at 1350 nm by Cerenkov radiation in higher-order-mode fiber,” Optics Lett., vol. 32, p. 1053, 2007.
  92. P. Hamel, Y. Jaouën, R. Gabet and S. Ramachandran, “Optical Low Coherence Reflectometry for complete chromatic dispersion characterization of few-mode fibers,” Optics Lett., vol. 32, p. 1029, 2007.
  93. J.M. Fini and S. Ramachandran, “Natural bend-distortion immunity of higher-order-mode large-mode-area fibers,” Optics Lett., vol. 32, p. 748, 2007.
  94. J.V. Howe, J.H. Lee, S. Zhou, F. Wise, C. Xu, S. Ramachandran, S. Ghalmi and M.F. Yan, “Demonstration of soliton self-frequency shift below 1300 nm in higher-order-mode, solid silica-based fiber,” Optics Lett., vol. 32, p. 340, 2007.
  95. J.W. Nicholson, S. Ramachandran, S. Ghalmi, M.F. Yan, P. Wisk, E. Monberg and F.V. Dimarcello, “Propagation of femtosecond pulses in large-mode-area, higher-order-mode fiber,” Optics Lett., vol. 31, p. 3191, 2006.
  96. S. Ramachandran, S. Ghalmi, J.W. Nicholson, M.F. Yan, P. Wisk, E. Monberg and F.V. Dimarcello, “Anomalous Dispersion in a Solid, Silica-based Fiber,” Optics Lett., vol. 31, p. 2532, 2006.
  97. S. Ramachandran, J.W. Nicholson, S. Ghalmi, M.F. Yan, P. Wisk, E. Monberg and F.V. Dimarcello, “Light propagation with ultra-large modal areas in optical fibers,” Optics Lett., vol. 31, p. 1797, 2006.
  98. S. Ramachandran, M.F. Yan, J. Jasapara, P. Wisk, S. Ghalmi, E. Monberg and F.V. Dimarcello, “High Energy (nanojoule) Femtosecond Pulse Delivery with Highly Dispersive Higher Order Mode Fibers,” Optics Lett., vol. 30, p. 3225, 2005.
  99. S. Ramachandran, S. Golowich, M.F. Yan, E. Monberg, F.V. Dimarcello, J. Fleming, S. Ghalmi and P. Wisk, “Lifting polarisation degeneracy of modes by fiber design: a platform for polarisation insensitive microbend fiber gratings,” Optics Lett., vol. 30, p. 2864, 2005.
  100. S. Ramachandran, “Dispersion-tailored few-mode fibers: a versatile platform for in-fiber photonic devices,” J. Lightwave Tech., vol. 23, p. 3426, 2005.
  101. S. Golowich and S. Ramachandran, “On the polarisation dependence of microbend fiber gratings: Relation to fiber design,” Optics Exp., vol. 13, p. 6879, 2005.
  102. Z. Wang, J.R. Heflin, R.H. Stolen and S. Ramachandran, “Highly sensitive optical response of optical fiber long period gratings to nm-thick ionic self-assembled multilayers,” Appl. Phys. Lett., vol. 86, 223104, 2005.
  103. Z. Wang, J.R. Heflin, R.H. Stolen and S. Ramachandran, “Analysis of optical response of long period fiber gratings to nm-thick thin-film coatings,” Optics Exp., vol. 13, p. 2808, 2005.
  104. S. Ramachandran and S.G. Bishop, “Photoinduced integrated-optic devices in rapid thermally annealed chalcogenide glasses,” IEEE J. Selected Topics Quant. Electronics, vol. 11, p. 260, 2005.
  105. S. Ramachandran, S. Ghalmi, J. Bromage, S. Chandrasekhar and L.L. Buhl, “Evolution and systems impact of coherent distributed multi-path interference,” IEEE Photon. Tech. Lett., vol. 17, p. 238, 2005.
  106. C. Dorrer and S. Ramachandran, “Self-referencing dispersion characterization of multimode structures using direct instantaneous frequency measurement,” IEEE Photon. Tech. Lett., vol. 16, p. 1700, 2004.
  107. Z. Wang and S. Ramachandran, “Ultrasensitive long-period fiber gratings for broadband modulators and sensors,” Optics Lett., vol. 28, p. 2458, 2003.
  108. B.R. Acharya, S. Ramachandran, T. Krupenkine, C.C. Huang and J.A. Rogers, “Tunable optical fiber devices based on broadband long period gratings and pumped microfluidics,” App. Phys. Lett., vol. 83, p. 4912, 2003.
  109. F. Cattaneo, K. Baldwin, S. Yang, T. Krupenkine, S. Ramachandran and J.A. Rogers, “Digitally tunable microfluidic fiber devices,” J. Microelectromechanical Sys., vol. 12, p. 907, 2003
  110. S. Ramachandran, M.F. Yan, E. Monberg, F.V. Dimarcello, P. Wisk and S. Ghalmi, “Record bandwidth, spectrally flat coupling with microbend gratings in dispersion-tailored fibers,” IEEE Photon. Tech. Lett., vol. 15, p. 1561, 2003.
  111. S. Ramachandran, “Novel photonic devices in few mode fibers,” Invited paper, IEE Proc. – Circuits Devices Sys., vol. 150, p. 473, 2003.
  112. S. Ramachandran, J.W. Nicholson, S. Ghalmi and M.F. Yan, “Measurement of multi-path interference in the coherent cross-talk regime,” IEEE Photon. Tech. Lett., vol. 15, p. 1171, 2003.
  113. J.W. Nicholson, S. Ramachandran, S. Ghalmi, E. Monberg, F. DiMarcello, M. Yan, P. Wisk and J. Fleming, “Electrical spectrum measurements of dispersion in higher order mode fibers,” IEEE Photon. Tech. Lett., vol. 15, p. 831, 2003.
  114. S. Ramachandran, S. Ghalmi, S. Chandrasekhar, I. Ryazansky, M.F. Yan, F.V. Dimarcello, W.A. Reed and P. Wisk, “Tunable dispersion compensators with higher-order-mode fibers,” IEEE Photon. Tech. Lett., vol. 15, p. 727, 2003.
  115. S. Ghalmi, S. Ramachandran, E. Monberg, Z. Wang, M.F. Yan, F.V. Dimarcello, W.A. Reed, P. Wisk and  J. Fleming, “Low loss, all-fiber high-order mode dispersion compensators for lumped or multi-span compensation,” Electron. Lett., vol. 38, p. 1507, 2002.
  116. S. Ramachandran, M. Das, Z. Wang, J. Fleming, and M.F. Yan, “High extinction, broadband polarisers using long-period fiber-gratings in few-mode fibers,” Electron. Lett., vol. 38, p. 1327, 2002.
  117. S. Ramachandran, S. Ghalmi, Z. Wang, and M.F. Yan, “Band-Selection Filters using Concatenated Long-Period Gratings in Few-mode Fibers,” Optics Lett., vol. 27, p. 1678, 2002.
  118. S. Ramachandran, Z. Wang and M.F. Yan, “Bandwidth control of long-period grating-based mode-converters in few-mode fibers,” Optics Lett., vol. 27, p. 698, 2002.
  119. S. Ramachandran, G. Raybon, B. Mikkelsen, M.F. Yan, L. Cowsar and R-J. Essiambre, “1700-km Transmission at 40-Gb/s with 100-km Amplifier-Spacing Enabled by Higher-Order-Mode Dispersion-Compensation,” Electron. Lett., vol. 37, p. 1352, 2001.
  120. S. Ramachandran, B. Mikkelsen, L. C. Cowsar, M. F. Yan, G. Raybon, L. Boivin, M. Fishteyn, W. A. Reed, P. Wisk, D. Brownlow, R. G. Huff, and L. Gruner-Nielsen, “All-Fiber Grating-Based Higher Order Mode Dispersion Compensator for Broad-Band Compensation and 1000-km Transmission at 40 Gb/s,” Photon. Tech. Lett., vol. 13, p.632, 2001.
  121. S. Ramachandran and S.G. Bishop, “Low loss photoinduced waveguides in rapid thermally annealed films of chalcogenide glasses,” Appl. Phys. Lett., vol. 74, p13, 1999.
  122. S. Ramachandran and S. G. Bishop, “Excitation of Er3+ emission by host glass absorption in sputtered films of Er-doped Ge10As40Se25S25 glass,” Appl. Phys. Lett., vol. 73, p3196, 1998.
  123. S. Ramachandran, J.C. Pepper, D.J. Brady, S.G. Bishop, “Micro-optical lenslets by photo-expansion in chalcogenide glasses,” J. Lightwave Tech., vol. 15, p. 1371, 1997.
  124. S. Ramachandran, S.G. Bishop, J.P. Guo, D.J. Brady, “Fabrication of holographic gratings in As2S3 glass by photoexpansion and photodarkening,” IEEE Photon. Tech. Lett., vol. 8, p. 1041, 1996.
  125. S. Q. Gu, S. Ramachandran, E. E. Reuter, D. A. Turnbull, J. T. Verdeyen, and S. G. Bishop, “Photoluminescence and excitation spectroscopy of Er-doped As2S3 glass: Novel broad band excitation mechanism,” J. Appl. Phys., vol. 77, p. 3365, 1995.
  126. S. Q. Gu, S. Ramachandran, E. E. Reuter, D. A. Turnbull, J. T. Verdeyen, and S. G. Bishop, “Novel broad-band excitation of Er3+ luminescence in chalcogenide glasses,” Appl. Phys. Lett, vol. 66, p. 670, 1995.
Select Presentations
  1. S. Ramachandran, “Scaling fiber mode counts to 100 and beyond: Light guidance via Topological Confinement,” Invited Talk, CLEO Pacific Rim, 2024.
  2. S. Ramachandran, “Topological Confinement: a new mechanism for light transport in optical fibers,” Hot Topics, Plenary Session, Photonics West 2024.
  3. S. Ramachandran, “High Dimensional Structured Light Quantum Sources,” Invited Talk, Photonics West 2024.
  4. S. Ramachandran, “Multimode Fiber Nonlinear Optics,” Short Course, ASSL/FIO 2023.
  5. S. Ramachandran, “High-dimensional quantum sources via multimode nonlinearities in fibers, Invited Talk, IEEE Summer Topicals 2023.
  6. S. Ramachandran, “Fiber Mode Count Scalability via Topological Confinement,” Invited Talk, OECC 2023.
  7. S. Ramachandran, “The physics and applications of topologically complex light, Invited Talk, APS March Meeting 2023.
  8. S. Ramachandran, “Scaling modal capacity of fibers by exploiting topological properties of light,” Invited Talk, OFC 2023.
  9. S. Ramachandran, “Multimode Nonlinear Fiber Optics,” Plenary Lecture, AFL 2022.
  10. S. Ramachandran, “Quantum Source Engineering in Higher Dimension,” Invited Talk, Student Conference on Optics and Photonics, 2022.
  11. S. Ramachandran, “Spatially, vectorially and topologically complex light in fibers: Implications & Applications,” Tutorial, ECOC 2022.
  12. Ramachandran, “Scaling fiber modal capacity by topological confinement,” Invited Talk, Workshop, ECOC 2022.
  13. S. Ramachandran, “Structured Light in Fibres: Principles and Applications,” Invited Talk, ICO Congress 2022.
  14. S. Ramachandran, “Nonlinear Optics meets Topological Photonics: the Influence of Angular Momentum and Chirality on Fiber Nonlinear Optics,” Tutorial, CIVIS Workshop on Multimode Photonics 2022.
  15. S. Ramachandran, “Topological guidance of light: a new mechanism for light transport,” Invited Talk, IEEE Summer Topicals 2022.
  16. S. Ramachandran, “High Dimensional Quantum Sources with Optical Fibers,” Invited Talk, ICOAM 2022.
  17. S. Ramachandran, “Sensing and Imaging with Topologically Complex Light, Invited Talk, Winter Colloquium on Physics of Quantum Electronics (PQE) 2022.
  18. S. Ramachandran, “Multimode Fiber Optics: recent paradigm shifts driving its resurgence,” Plenary Lecture, USST Young Scientist Forum, 2021.
  19. S. Ramachandran, “Nonlinear optics influenced by light’s topological structure,” Invited Talk, OSI Symposium 2021.
  20. Z. Ma, P. Kristensen, S. Ramachandran, “Record (60) Uncoupled Modes in A Step-Index Fiber due to A New Light Guidance Mechanism: Topological Confinement,” High-scored paper, Tu4A.3, ECOC 2021.
  21. S. Ramachandran, “Optical Activity in Strictly Isotropic Materials (Fibers),” Invited Talk, OSA-FIO 2020.
  22. H.B. Kabagöz, A. Antikainen, S. Ramachandran, “Time-Locked Multi-Color Single-Aperture Fiber Sources via Soliton Self-Mode Conversion,” Invited Talk, Th-A2.1, EuroPhoton 2020.
  23. S. Ramachandran, “Linear, nonlinear and peculiar properties of OAM fiber modes,” Tutorial, IEEE Summer 2020.
  24. S. Ramachandran, “Four-Wave Mixing (FWM) with OAM modes in fibers,” Invited Talk, ACP 2019.
  25. S. Ramachandran, “The influence of OAM in fiber nonlinear optics,” Invited Talk, IEEE-IPS Annual, 2019.
  26. S. Ramachandran, “Space: the less explored dimension of light,” Short Course, Siegman School on Lasers, 2019
  27. S. Ramachandran, “Nonlinear optics exploiting the spatial dimension,” Keynote, CLEO-Europe, 2019.
  28. S. Ramachandran, “Spin-orbit interactions of light in optical fibers,” Invited Talk, ICOAM 2019.
  29. S. Ramachandran, “Structured light in fibers: Physics & Applications,” Keynote, IMCO 2019.
  30. S. Ramachandran, “The physics and applications of fibers supporting OAM,” Invited Talk, EXAT symposium, 2019.
  31. A.P. Peterson-Greenberg, G. Prabhakar, S. Ramachandran, “Single-shot, sub-picometer-resolution wavemeter using topologically enhanced optical activity of OAM fiber modes,” Post-deadline paper. JTh5A.9, CLEO 2019.
  32. S. Ramachandran and G.P. Agrawal, “Soliton Self-Mode Conversion (SSMC): Power-scalable frequency conversion with multimode fibers,” Invited Talk, SPIE Photonics West, 2019.
  33. V. Balaswamy, S. Ramachandran, V.R. Supradeepa, “High power, widely tunable, cascaded Raman fiber laser with near complete wavelength conversion,’ Post-deadline paper, ASSL 2018.
  34. S. Ramachandran, “Physics of guided-wave light propagation: Applications to fiber lasers and nonlinear optics,” Short Course, ASSL 2018.
  35. S. Ramachandran and G.P. Agrawal, “Soliton Self-Mode Conversion (SSMC): Revisiting ultrashort pulse Raman scattering,” Invited Talk, ERC Workshop, 2018.
  36. S. Ramachandran, “Classical and Quantum Communications with OAM in fibers,” Invited Talk, IEEE Annual Meeting, 2018.
  37. D. Cozzolino, D. Bacco, B. Da Lio, K. Ingerslev, Y. Ding, K. Dalgaard, P. Kristensen, M. Galili, K. Rottwitt, S. Ramachandran and L.K. Oxenløwe “High-dimensional quantum communication with twisted photons propagating in a fiber link,” Plenary, Asian Quantum Information Science Conference, 2018.
  38. S. Ramachandran, “Opto-mechanical interactions with OAM states,” Invited Talk, CLEO-PR, 2018.
  39. S. Ramachandran, “Intermodal nonlinear optics in step-index fibers,” Invited Talk, IEEE Summer Topicals, 2018.
  40. S. Ramachandran, “Space – the less explored dimension of light,” Plenary, IONS Denmark, 2018.
  41. S. Ramachandran, “Intermodal nonlinear optics in fibers,” Invited Talk, IEEE Summer Topicals, 2018.
  42. S. Ramachandran, “Multimode Nonlinear Fiber Optics: New opportunities & challenges,” Tutorial, CLEO 2018.
  43. S. Ramachandran, “Power scalable nonlinear optics in multimode fibers,” Invited Talk, JSAP 2018.
  44. S. Ramachandran, “OAM in fibers: how they are different from other fiber modes,” Invited Talk, OFC 2018.
  45. S. Ramachandran, “Scaling power and creating new colour sources via multimode nonlinear fiber optics, Tutorial, ACP 2017.
  46. S. Ramachandran, “OAM in fibers: differences from OAM in free space and other fiber modes,” Invited Talk, ACP 2017.
  47. S. Ramachandran, “OAM in Optical Fibers: similarities with, and differences from, OAM in free space,” Invited Talk, ICOAM, 2017.
  48. S. Ramachandran, “Orbital Angular Momentum (OAM) of light in fiber,” Invited Talk, ICO-24, 2017.
  49. S. Ramachandran, “Intermodal nonlinear optics with Bessel and OAM beams in fibers,” Invited Talk, OSA Nonlinear Optics, 2017.
  50. S. Ramachandran, “MW power level fiber nonlinear optics via intermodal interactions” Invited Talk, ISUPT 2017.
  51. J. Demas, L. Rishoj, X. Liu, G. Prabhakar, S. Ramachandran, “High-power, wavelength-tunable NIR all-fiber lasers via intermodal four-wave mixing,” Post-deadline paper, JTh5A.8, CLEO 2017.
  52. S. Ramachandran, “Fiber sources with structured light for biomedical imaging,” Invited Talk, Photonics 2016.
  53. J. Demas, G. Prabhakar, T. He, P. Kristensen, S. Ramachandran, “High peak power 974 nm fiber source employing parametric wavelength conversion with HOM fibers,” ATu6A.2, Post-deadline paper, ASSL 2016.
  54. S. Ramachandran, “Multimode Nonlinear Fiber Optics with Structured Light,” ATh1A.1, Invited Talk, ASSL 2016.
  55. S. Ramachandran, “How uncoupled can OAM modes remain in fibers?” Invited Talk, SDM workshop, ECOC 2016.
  56. S. Ramachandran, “Linear and Nonlinear Properties of OAM in Fibers,” Invited Talk, ECOC 2016.
  57. S. Ramachandran, “Intermodal nonlinear fiber optics: a new pathway to power scalable sources,” Keynote Address, Europhoton 2016.
  58. S. Ramachandran, “Light’s angular momentum in fiber,” Tutorial, OSA Summer Topicals 2016.
  59. S. Ramachandran, “On the Orbital Angular Momentum (OAM) of light in fiber, Tutorial, OECC 2016.
  60. P. Gregg, P. Kristensen, A. Rubano, S. Golowich, L. Marrucci and S. Ramachandran, “Spin-Orbit Coupled, Non-Integer OAM Fibers: Unlocking a New Eigenbasis for Transmitting 24 Uncoupled Modes,” Post-deadline paper, CLEO-2016.
  61. S. Ramachandran, “OAM in fibers: how they are similar to, and different from, OAM in free space,” Invited Talk, Royal Society, UK, 2016.
  62. Y. Jung, Q. Kang, S. Yoo, S. Raghuraman, D. Ho, P. Gregg, S. Ramachandran, S.U. Alam, D.J. Richardson, “Optical Orbital Angular Momentum Amplifier based on an Air-Core Erbium Doped Fiber,” Post-deadline paper No. Th5A.5, OFC-2016.
  63. S. Ramachandran, “Light’s angular momentum in fiber,” Invited Talk, WRAP 2015.
  64. S. Ramachandran, “Optical vortices in fiber,” Invited Talk, OSA Annual Meeting/FIO, 2015.
  65. S. Ramachandran, “High energy nonlinear optics in fiber,” Invited Talk, CLEO-PR 2015.
  66. S. Ramachandran, “OAM modes as data channels in fiber,” Invited Talk, EXAT symposium, 2015.
  67. S. Ramachandran, “Low cross-talk fibers using OAM,” Invited Talk, SDM workshop, OSA summer topicals, 2015.
  68. S. Ramachandran, “Physics of guided-wave light propagation: Applications to fiber lasers and nonlinear optics,” Short Course , EuroPhoton 2014.
  69. S. Ramachandran, “Fibers supporting OAM and their applications,” Invited Talk, OFC 2014.
  70. S. Ramachandran, L. Yan, P. Gregg and P. Kristensen, “Light that spins inside fibers: Applications from microscopy to telecommunications,” Invited Talk, OSA Annual Meeting FIO/LS, 2013.
  71. S. Ramachandran, P. Steinvurzel, J. Demas, B. Tai and Y. Chen, “Can Fibers replace OPOs?” Invited Talk, IEEE Photonics Society Annual Meeting, 2013.
  72. S. Ramachandran and P. Gregg, “Looking inside a fiber: measuring mode content & properties,” Tutorial, IEEE Summer Topicals, 2013.
  73. S. Golowich, N. Bozinovic, P. Kristensen, P. Gregg and S. Ramachandran, “Orbital angular momentum states for mode division multiplexing in optical fiber,” Invited Talk, IEEE Summer Topicals, 2013.
  74. S. Ramachandran and P. Kristensen, “Scaling capacity by twisting light beams,” Invited Talk, Optoelectronics and Comm. Conf. & CLEO-Pacific Rim, Kyoto, 2013.
  75. S. Ramachandran, P. Steinvurzel and J. Demas, “A new route to high-energy nonlinear fiber optics,” Invited Talk, Optoelectronics and Comm. Conf. & CLEO-Pacific Rim, Kyoto, 2013.
  76. S. Ramachandran, “Few-mode fibers: from devices to long-distance transmission,” Invited Talk, Workshop on SDM technologies, OFC -2013.
  77. S. Ramachandran, N. Bozinovic, P. Gregg, S.E. Golowich, P. Kristensen, “Scaling Capacity by Spinning Light inside Fibers,” Invited Talk, Photonics West (SPIE) 2013.
  78. N. Bozinovic, Y. Yue, Y. Ren, M. Tur, P. Kristensen, A.E. Willner, S. Ramachandran, “Orbital Angular Momentum (OAM) based Mode Division Multiplexing (MDM) over a km-length Fiber,” Post-deadline Paper, Th.3.C.6, European Conf. Opt. Comm. (ECOC), 2012.
  79. S. Ramachandran, N. Bozinovic, P. Gregg, S.E. Golowich, P. Kristensen, “Optical vortices in fibres: A new degree of freedom for mode multiplexing,” Invited Talk, European Conf. Opt. Comm. (ECOC), 2012.
  80. S. Ramachandran, “How to measure (inter/intra) modal purity, and is this important for MDM?” Invited Talk, Workshop on Optical components and characterisation requirements for SDM networks, European Conf. Opt. Comm. (ECOC), 2012.
  81. S. Golowich, P. Kristensen, N. Bozinovic, P. Gregg, and S. Ramachandran, “Fibers Supporting Orbital Angular Momentum States for Information Capacity Scaling,” Invited Talk, OSA Annual Meeting FIO/LS, 2012.
  82. S. Ramachandran, P. Kristensen, “Light that spins inside fibers,” Invited Talk, OSA Summer Topicals, 2012.
  83. N. Bozinovic, S. Ramachandran, M. Brodsky, P. Kristensen, “Record-length transmission of photons entangled in orbital angular momentum (OAM),” Post-deadline paper, OSA Annual Meeting FIO/LS, 2011.
  84. S. Ramachandran, “Twisted light in a fiber: Science and Applications,” Invited Talk, Optoelectronics and Communications Conference, 2011 .
  85. S. Ramachandran, “Sensing with Gratings, Nanolayers & Complex Beams, in Optical Fibers,” Invited Talk, Optical Fiber Sensors Conference, 2011.
  86. D. N. Schimpf, R. A. Barankov, K. Jespersen, S. Ramachandran, “Modal content reconstruction of few-mode fibers by using optical low-coherence interferometry,” Post-deadline Paper, Photonics West, 2011.
  87. S. Ramachandran, “Doughnut Beams: Ramifications of Optical Vortices in Fibers,” Invited Talk, Photonics-2010
  88. S. Ramachandran, “Physics and Applications of Optical Vortices in Fibers,” Invited Talk, IEEE-LEOS Annual Meeting 2010.
  89. S. Ramachandran “Making light of M2 ≠ 1: Fiber sources with spatial singularities,” Invited Talk, NSF fiber workshop, 2010.
  90. S. Ramachandran, “Fiber light sources using structured beams,” Invited Talk, EuroPhoton, Hamburg, 2010.
  91. J.W. Nicholson, A.M. DeSantolo, S. Ghalmi, J.M. Fini, J. Fleming, E. Monberg, F. Dimarcello, S. Ramachandran, “Nanosecond Pulse Amplification in a Higher-Order Mode Er-Doped Fiber Amplifier,” Post-deadline Paper, CLEO 2010.
  92. S. Ramachandran, C. Smith, P. Balling, P. Kristensen, “Multi-Colour Vortex Beam Generation by Cascaded Raman Processes in Optical Fibers,” Post-deadline Paper , Photonics West, 2010.
  93. S. Ramachandran, “Structured light in optical fibers: Beams that can do what Gaussians cannot,” Tutorial, European Conf. Optical Comm.,2009.
  94. K. Rottwitt and S. Ramachandran, “Spontaneous emission from saturated parametric amplifiers,” Invited Talk, ICTON-2009.
  95. J.M. Fini, P.I. Borel, P.A. Weimann, P. Kristensen, J. Bjerregaard, K. Carlson, M.F. Yan, P.W. Wisk, S. Ramachandran, A.D. Yablon, D.J. DiGiovanni, D.Trevor, C.J. Martin, A. McCurdy, “Bend Insensitive Fiber for FTTX Applications,” Invited Talk, OTuI4, Optical Fiber Comm.,2009.
  96. S. Ramachandran, “Spatially structured light in optical fibers for high-power lasers,” Invited Talk, OSA Topical on Advanced Solid State Photonics, 2009.
  97. S. Ramachandran, “A new class of fibers for the management of ultra-short pulses,” Invited Talk, IEEE-LEOS Winter Topcials, 2009.
  98. S. Ramachandran, “Radially polarised (vector) beams in optical fibers, Invited Talk, Photonics-2008.
  99. S. Ramachandran, “Tailoring light, spatially and vectorially, with optical fibers,” Keynote Lecture, NICT International Symposium, Tokyo, Japan, 2008.
  100. S. Ramachandran, “Diffraction-resistant light (Bessel beams) from optical fibers,” Invited Talk, Asia Optical Exposition, 2008.
  101. S. Ramachandran and S. Ghalmi, “Diffraction-free, self-healing Bessel beams from fibers,” Post-deadline Paper, CPDB5, Conf. Lasers & Electro-optics, 2008.
  102. S. Ramachandran, “Lasers and amplifiers with ultra-large mode area fibers,” Invited Talk, Optical Soc. America Annual Meeting, 2007.
  103. S. Ramachandran, “Anomalous dispersion in fibers: Applications in the NIR and visible,” Invited Talk, Optoelectronics and Comm. Conf., Yokohama, 2007
  104. S. Ramachandran, S. Ghalmi and M F. Yan, “Ultra-Large Modal Area Fibers,” Invited Talk, Conf. Lasers & Electro-optics, 2007.
  105. J.H. Lee, J.V. Howe, C. Xu, S. Ramachandran and S. Ghalmi, “Energetic Soliton Self-Frequency Shift below 1300 nm over a 240 nm Range in a Solid Silica-Based Fiber, Post-deadline Paper, PDP38, Optical Fiber Comm.,2007.
  106. S. Ramachandran, J.W. Nicholson and M F. Yan, “Novel fibers for ultra-short and high-power pulses,” Invited Talk, Optical Fiber Comm.,2007.
  107. S. Ramachandran, K. Brar, S. Ghalmi, K. Aiso, M. Yan, D. Trevor, J. Fleming, C. Headley, P. Wisk, G. Zydzik, M. Fishteyn, E. Monberg, F. Dimarcello, “High-power amplification in a 2040-mm2 higher order mode,” Post-deadline Paper, LBN-7, Photonics West, 2007.
  108. S. Ramachandran, “Ultra-large mode area fibers: Approaches & Realisations, Invited Talk, Photon. West, 2007.
  109. S. Ramachandran, “Robust light propagation in fibers with ultra-large modal areas,” Invited Talk, Photon-2006.
  110. S. Ramachandran, S. Ghalmi, M F. Yan, J.W. Nicholson, J. Fleming, P. Wisk, E. Monberg, F.V. Dimarcello, “Novel Fibers using Higher Order Modes: Applications to Femtosecond Pulses,” Invited Talk, IEEE- Lasers & Electro-optics Annual Meeting, 2006.
  111. S. Ramachandran, “Robust light propagation in fibers with ultra-large modal areas,” Invited Talk, European Conf. Optical Comm.,2006.
  112. S. Ramachandran, S. Ghalmi, J.W. Nicholson, M.F. Yan, P. Wisk, E. Monberg and F.V. Dimarcello, “Demonstration of Anomalous Dispersion in a Solid, Silica-based Fiber at l < 1300 nm,” Post-deadline Paper PDP3, Optical Fibers Comm., 2006.
  113. D.J. DiGiovanni, A. Yablon, S. Ramachandran, J. Fini, Y. Emori and C. Headley, “Progress in all-fiber components,” Invited Talk, Photonics West 2006.
  114. S. Ramachandran, “High Energy, Low Nonlinearity Femtosecond Pulse Compression and Delivery, with Dispersion Tailored Higher Order Mode Fibers,” Invited Talk, ICOL-2005; India.
  115. S. Ramachandran, J.W. Nicholson, S. Ghalmi, M.F. Yan, P. Wisk, E.Monberg and F.V. Dimarcello, “Robust, Single-Moded, Broadband Transmission and Pulse Compression in a Record Aeff (2100 um2) Higher-Order-Mode Fiber,” Post-deadline Paper Th4.4.1, European Conf. Optical Comm., 2005.
  116. S. Ramachandran, M.F. Yan, J. Jasapara, P. Wisk, S. Ghalmi, E.Monberg and F.V. Dimarcello, “10x Higher Energy Femtosecond Pulse Delivery than SMF with Record Dispersion Higher Order Mode Fiber,” Post-deadline Paper, OSA Topical on Optical Amplifiers and their Applications, 2005.
  117. Siddharth Ramachandran, “Managing noise from modal interference: is single mode fiber a necessity?” Invited Talk, Photonics, 2004.
  118. Siddharth Ramachandran, “Novel Photonics devices in Few-Mode Fibers,” Invited Talk: ICOCN, 2004.
  119. Siddharth Ramachandran, “Dispersion management with few mode fibers,” Invited talk, Optoelectronics & Comm. Conf., 2003.
  120. Siddharth Ramachandran, “Novel grating devices in few-mode fibers,” Invited talk, OSA Topical on Bragg Gratings, Photosensitivity and Poling, 2003.
  121. Siddharth Ramachandran, “Novel photonic devices in few-mode fibers,” Paper No. FBR 2.1, Invited talk, Photonics, 2002.
  122. S. Ramachandran, S. Ghalmi, S. Chandrasekhar, I. Ryazansky, M.F. Yan, F.V. Dimarcello, W.A. Reed and P. Wisk, “Wavelength-continuous broadband adjustable dispersion compensator using higher order mode fibers and switchable fiber-gratings,” Post-deadline Paper PD 2.6, European Conf. Optical Comm., 2002.
  123. Siddharth Ramachandran, “Higher-Order-Mode Dispersion Compensation for Broadband Dispersion and Non-linearity Management in Transmission Systems,” Invited Talk WU-5, Opt. Fiber Comm., 2002.
  124. Siddharth Ramachandran, Samir Ghalmi, Zhiyong Wang, Kenneth Feder and Man Yan, “Dispersion-free, Tunable Band-Selection Filters using Long-Period Gratings in Few-moded Fibers”, Post-deadline Paper PD-1, OSA Topical on Bragg Gratings, Photosensitivity and Poling, 2001.
  125. S. Ramachandran, “Higher-Order-Mode Dispersion-Compensation: Enabler for long-distance WDM at 40 Gb/s,” Invited Talk Paper No. 4532-34, ITCOM (SPIE), 2001.
  126. S. Ramachandran, B. Mikkelsen, L.C. Cowsar, M.F. Yan, G. Raybon, L. Boivin, M. Fishteyn, W.A. Reed, P. Wisk, D. Brownlow and L. Gruner-Nielsen, “All-fiber, grating-based, higher-order-mode dispersion compensator for broadband compensation and 1000-km transmission at 40 Gb/s,” Post-deadline Paper PD-2.5, European Conf. Optical Comm., 2000
Books/Book Chapters
  1. Y. Jung, S. Alam, D.J. Richardson, S. Ramachandran and K.S. Abedin, “Multicore and multimode optical amplifiers for space division multiplexing,” in Optical Fiber Telecommunications VII, Chapter 7,  A.E. Willner, Ed., Academic Press, 2020.
  2. J. Wang, M.J. Padgett, S. Ramachandran, N, Bozinovic, S. Golowich, M.P.J. Lavery, H. Huang, Y. Yue, A.E. Willner “Multimode communications using OAM,” in Optical Fiber Telecommunications VI-B, I. Kaminow, T. Li, A.E. Willner, Ed., Academic Press, 2013.
  3. Fiber-based dispersion compensation, S. Ramachandran, Editor, Springer, New York, 2007.
  4. S. Ramachandran and M.F. Yan, “Static and tunable dispersion management with higher order mode fibers,” in Fiber-based dispersion compensation, S. Ramachandran, Ed., Springer, New York, 2007.
  5. S. Ramachandran, “Dispersion-tailored higher order mode fibers for in-fiber photonic devices,” in Guided wave optical components and devices, B.P. Pal, Ed., Elsevier, Burlington, 2005.
Patents
  1. “Tunable polarizers,” S. Ramachandran, US Patent 6768824.
  2. “Tunable mode-converters using few mode fibers,” S. Ramachandran, US Patent 6768835.
  3. “Optical fiber-based device with tunable birefringence,” S. Ramachandran, US Patent 6778715.
  4. “Optical bandpass filter using long period gratings,” S. Ramachandran, US Patent 6845194.
  5. “Optical bandpass filter using long period gratings,” S. Ramachandran, US Patent 6980578.
  6. “Adjustable dispersion compensator with few mode fibers and switchable mode converters,” S. Ramachandran, US Patent 6937788.
  7. “Highly index-sensitive optical devices including long period gratings,” S. Ramachandran, US Patent 6950578.
  8. “Optical fiber having enhanced separation of HOMs,” S.E. Golowich, S. Ramachandran, US Patent 7110651.
  9. “Large mode area fibers using higher order modes,” D.J. Digiovanni, S. Ramachandran, US Patent 7171074.
  10. “Large mode area fibers using higher order modes,” D.J. Digiovanni, S. Ramachandran, US Patent 7272288.
  11. “Large mode area fibers using higher order modes,” D.J. Digiovanni, S. Ramachandran, US Patent 7386209.
  12. “Large mode area fibers using higher order modes,” D.J. Digiovanni, S. Ramachandran, US Patent 7483612.
  13. “Polarization insensitive microbend fiber gratings and devices using the same,” S. Ramachandran, US Patent 7177510.
  14. “Polarization insensitive microbend fiber gratings and devices using the same,” S. Ramachandran, US Patent 7340132.
  15. “Polarization insensitive microbend fiber gratings and devices using the same,” S. Ramachandran, US Patent 7340139.
  16. “Polarization insensitive microbend fiber gratings and devices using the same,” S. Ramachandran, US Patent 7352939.
  17. “Polarization insensitive microbend fiber gratings and devices using the same,” S. Ramachandran, US Patent 7519254.
  18. “Short pulse lasers using large mode area fibers and higher order modes,” S. Ramachandran, J.W. Nicholson, US Patent 7228029.
  19. “Fiber structure with improved bend resistance,” J.M. Fini, S. Ramachandran, US Patent 7257293.
  20. “Fiber optic sensor or modulator using tuning of long period gratings with self-assembled layers,” Z. Wang, J.R. Heflin, S. Ramachandran, US Patent 7336861.
  21. “Achieving gaussian outputs from large-mode-area-higher-order mode fibers,” G. Leuchs, N. Lindlein, S. Ramachandran, US Patent 7672552.
  22. “Measuring modal content of multi-moded fibers,” P. Kristensen, J.W. Nicholson, S. Ramachandran, A.D. Yablon, US Patent 7817258.
  23. “Visible continuum generation utilizing a hybrid optical source,” J.W. Nicholson, S. Ramachandran, US Patent 7826499.
  24. “Locally perturbed optical fibers for mode transformers,” S. Ramachandran, M. Sumetsky, P.S. Westbrook, US Patent 7865045.
  25. “Pumping in a higher-order mode that is different from a signal mode,” S. Ramachandran, US Patent 7925128.
  26. “Phase-engineered fibers for generating cylindrical vector beams,” S. Ramachandran, US Patent 7941012.
  27. “Sequentially increasing effective area in higher-order mode (HOM) Signal Propagation,” D.J. Digiovanni, S. Ramachandran, US Patent 8000570.
  28. “Preventing dielectric breakdown in optical fibers,” S. Ramachandran, A.D. Yablon, US Patent 8103142.
  29. “Optical fibers and optical fiber devices with total dispersion greater than material dispersion,” S. Ramachandran, US Patent 8175435.
  30. “Optical fibers and optical fiber devices with total dispersion greater than material dispersion,” S. Ramachandran, US Patent 8175436.
  31. “Optical fibers and optical fiber devices with total dispersion greater than material dispersion,” S. Ramachandran, US Patent 8189977.
  32. “Production of optical pulses at a desired wavelength utilizing higher-order-mode (HOM) fiber,” S. Ramachandran, US Patent 8126299.
  33. “Production of optical pulses at a desired wavelength utilizing higher-order-mode (HOM) fiber,” S. Ramachandran, US Patent 8290317.
  34. “Systems and techniques for generating Bessel beams,” S. Ramachandran, US Patent: 8358888.
  35. “Segmented gain-doping of an optical fiber,” D.J. Digiovanni, S. Ramachandran, S. Ghalmi, M. Mermelstein, US Patent 8412015.
  36. “Compression of generated optical continuum utilizing higher-order-mode fiber,” J.W. Nicholson, S. Ramachandran, US Patent 8478134.
  37. “Non-linear optical system and techniques,” J.W. Nicholson, S. Ramachandran, US Patent 8507877.
  38. “Selectively pumping a gain-doped region of an optical fiber,” D.J. Digiovanni, S. Ramachandran, US Patent 8520299.
  39. “High-power fiber laser employing nonlinear wave mixing with higher-order modes,” S. Ramachandran, US Patent 9203209.
  40. “Optical fiber systems for delivering short high power pulses,” S. Ramachandran, S. Wielandy, US Patent 9417381.
  41. “Ultrashort pulse fiber laser employing Raman scattering in higher order mode fibers,” S. Ramachandran, L. Rishoj, J.D. Demas, US Patent 10734782.
  42. “Engineered optical fibers and uses thereof,” S. Ramachandran, G. Prabhakar, A.P. Greenberg, US Patent 10823667.
  43. “Optical imaging system employing vortex fiber for multiple-mode illumination,” S. Ramachandran, L. Yan, P. Kristensen, US Patent 10827911.
  44. “Optical fiber system employing topological guidance of light,” S. Ramachandran, Z. Ma, US Patent 11506841.