Nanostructured Fibers and Nonlinear Optics Lab
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Selected Presentations (keynote, tutorial, invited & post-deadline):

  1. S. Ramachandran, “Physics of guided-wave light propagation: Applications to fiber lasers and nonlinear optics,” Tutorial, EuroPhoton 2014.
  2. S. Ramachandran, “Fibers supporting OAM and their applications,” Invited Talk, OFC 2014.
  3. 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.
  4. S. Ramachandran, P. Steinvurzel, J. Demas, B. Tai and Y. Chen, “Can Fibers replace OPOs?” Invited Talk, IEEE Photonics Society Annual Meeting, 2013.
  5. S. Ramachandran and P. Gregg, “Looking inside a fiber: measuring mode content & properties,” Tutorial, IEEE Summer Topicals, 2013.
  6. 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.
  7. S. Ramachandran and P. Kristensen, “Scaling capacity by twisting light beams,” Invited Talk, Optoelectronics and Comm. Conf. & CLEO-Pacific Rim, Kyoto, 2013.
  8. 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.
  9. S. Ramachandran, “Few-mode fibers: from devices to long-distance transmission,” Invited Talk, Workshop on SDM technologies, OFC -2013.
  10. S. Ramachandran, N. Bozinovic, P. Gregg, S.E. Golowich, P. Kristensen, “Scaling Capacity by Spinning Light inside Fibers,” Invited Talk, Photonics West (SPIE) 2013.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. S. Ramachandran, P. Kristensen, “Light that spins inside fibers,” Invited Talk, OSA Summer Topicals, 2012.
  16. 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.
  17. S. Ramachandran, “Twisted light in a fiber: Science and Applications,” Invited Talk, Optoelectronics and Communications Conference, 2011 .
  18. S. Ramachandran, “Sensing with Gratings, Nanolayers & Complex Beams, in Optical Fibers,” Invited Talk, Optical Fiber Sensors Conference, 2011.
  19. 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.
  20. S. Ramachandran, “Doughnut Beams: Ramifications of Optical Vortices in Fibers,” Invited Talk, Photonics-2010
  21. S. Ramachandran, "Physics and Applications of Optical Vortices in Fibers," Invited Talk, IEEE-LEOS Annual Meeting 2010.
  22. S. Ramachandran “Making light of M2 ≠ 1: Fiber sources with spatial singularities,” Invited Talk, NSF fiber workshop, 2010.
  23. S. Ramachandran, "Fiber light sources using structured beams," Invited Talk, EuroPhoton, Hamburg, 2010.
  24. 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.
  25. 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.
  26. S. Ramachandran, “Structured light in optical fibers: Beams that can do what Gaussians cannot,” Tutorial, European Conf. Optical Comm.,2009.
  27. K. Rottwitt and S. Ramachandran, “Spontaneous emission from saturated parametric amplifiers,” Invited Talk, ICTON-2009.
  28. 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.
  29. S. Ramachandran, “Spatially structured light in optical fibers for high-power lasers,” Invited Talk, OSA Topical on Advanced Solid State Photonics, 2009.
  30. S. Ramachandran, “A new class of fibers for the management of ultra-short pulses,” Invited Talk, IEEE-LEOS Winter Topcials, 2009.
  31. S. Ramachandran, “Radially polarised (vector) beams in optical fibers, Invited Talk, Photonics-2008.
  32. S. Ramachandran, “Tailoring light, spatially and vectorially, with optical fibers,” Keynote Lecture, NICT International Symposium, Tokyo, Japan, 2008.
  33. S. Ramachandran, “Diffraction-resistant light (Bessel beams) from optical fibers,” Invited Talk, Asia Optical Exposition, 2008.
  34. S. Ramachandran and S. Ghalmi, “Diffraction-free, self-healing Bessel beams from fibers,” Post-deadline Paper, CPDB5, Conf. Lasers & Electro-optics, 2008.
  35. S. Ramachandran, “Lasers and amplifiers with ultra-large mode area fibers,” Invited Talk, Optical Soc. America Annual Meeting, 2007.
  36. S. Ramachandran, “Anomalous dispersion in fibers: Applications in the NIR and visible,” Invited Talk, Optoelectronics and Comm. Conf., Yokohama, 2007
  37. S. Ramachandran, S. Ghalmi and M F. Yan, “Ultra-Large Modal Area Fibers,” Invited Talk, Conf. Lasers & Electro-optics, 2007.
  38. 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.
  39. S. Ramachandran, J.W. Nicholson and M F. Yan, “Novel fibers for ultra-short and high-power pulses,” Invited Talk, Optical Fiber Comm.,2007.
  40. 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.
  41. S. Ramachandran, “Ultra-large mode area fibers: Approaches & Realisations, Invited Talk, Photon. West, 2007.
  42. S. Ramachandran, “Robust light propagation in fibers with ultra-large modal areas,” Invited Talk, Photon-2006.
  43. 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.
  44. S. Ramachandran, “Robust light propagation in fibers with ultra-large modal areas,” Invited Talk, European Conf. Optical Comm.,2006.
  45. 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.
  46. D.J. DiGiovanni, A. Yablon, S. Ramachandran, J. Fini, Y. Emori and C. Headley, “Progress in all-fiber components,” Invited Talk, Photonics West 2006.
  47. S. Ramachandran, “High Energy, Low Nonlinearity Femtosecond Pulse Compression and Delivery, with Dispersion Tailored Higher Order Mode Fibers,” Invited Talk, ICOL-2005; India.
  48. 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.
  49. 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.
  50. Siddharth Ramachandran, “Managing noise from modal interference: is single mode fiber a necessity?” Invited Talk, Photonics, 2004.
  51. Siddharth Ramachandran, “Novel Photonics devices in Few-Mode Fibers,” Invited Talk: ICOCN, 2004.
  52. Siddharth Ramachandran, “Dispersion management with few mode fibers,” Invited talk, Optoelectronics & Comm. Conf., 2003.
  53. Siddharth Ramachandran, “Novel grating devices in few-mode fibers,” Invited talk, OSA Topical on Bragg Gratings, Photosensitivity and Poling, 2003.
  54. Siddharth Ramachandran, “Novel photonic devices in few-mode fibers,” Paper No. FBR 2.1, Invited talk, Photonics, 2002.
  55. 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.
  56. 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.
  57. 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.
  58. 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.
  59. 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.

Journal Articles:

  1. J. Demas and S. Ramachandran, “Sub-second mode measurement of fibers using C2 imaging,” Opt. Exp. vol. 22, p. 23043, 2014.
  2. 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.
  3. 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.
  4. S. Ramachandran and P. Kristensen, “Optical vortices in fiber,”Invited Paper, J. Nanophotonics vol. 2, p. 455, 2013.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. R.A. Barankov, K. Wei, B. Samson and S. Ramachandran, “Resonant Bend Loss in Leakage Channel Fibers,” Optics Letters, vol. 37, p. 3147, 2012.
  13. D.N. Schimpf and S. Ramachandran, “Polarization-resolved imaging of an ensemble of waveguide modes,” Optics Letters, vol. 37, p. 3069, 2012.
  14. 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.
  15. 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.
  16. 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.
  17. S. Ramachandran, C. Smith, P. Kristensen, P. Balling, “Nonlinear generation of broadband polarisation vortices,” Optics Express, vol. 18, p. 23212, 2010.
  18. 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.
  19. 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.
  20. 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.
  21. 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.
  22. 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.
  23. 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.
  24. 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.
  25. M. Sumetsky and S. Ramachandran, “Multiple mode conversion and beam shaping with superimposed long period gratings,” Optics Express, vol. 16, p. 402, 2008.
  26. 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.
  27. 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.
  28. 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.
  29. 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.
  30. 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.
  31. 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.
  32. 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.
  33. 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.
  34. 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.
  35. 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.
  36. 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.
  37. 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.
  38. 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.
  39. 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.
  40. S. Ramachandran, “Dispersion-tailored few-mode fibers: a versatile platform for in-fiber photonic devices,” J. Lightwave Tech., vol. 23, p. 3426, 2005.
  41. S. Golowich and S. Ramachandran, “On the polarisation dependence of microbend fiber gratings: Relation to fiber design,” Optics Exp., vol. 13, p. 6879, 2005.
  42. 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.
  43. 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.
  44. 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.
  45. 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.
  46. 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.
  47. Z. Wang and S. Ramachandran, “Ultrasensitive long-period fiber gratings for broadband modulators and sensors,” Optics Lett., vol. 28, p. 2458, 2003.
  48. 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.
  49. 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
  50. 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.
  51. S. Ramachandran, “Novel photonic devices in few mode fibers,” Invited paper, IEE Proc. – Circuits Devices Sys., vol. 150, p. 473, 2003.
  52. 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.
  53. 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.
  54. 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.
  55. 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.
  56. 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.
  57. 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.
  58. 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.
  59. 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.
  60. 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.
  61. 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.
  62. 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.
  63. 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.
  64. 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.
  65. 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.
  66. 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.

Books, Book Chapters

  1. 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.
  2. Fiber-based dispersion compensation, S. Ramachandran, Editor, Springer, New York, 2007.
  3. 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.
  4. 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 8290317.
  33. “Systems and techniques for generating Bessel beams,” S. Ramachandran, US Patent: 8358888.
  34. “Segmented gain-doping of an optical fiber,” D.J. Digiovanni, S. Ramachandran, S. Ghalmi, M. Mermelstein, US Patent 8412015.
  35. “Compression of generated optical continuum utilizing higher-order-mode fiber,” J.W. Nicholson, S. Ramachandran, US Patent 8478134.
  36. “Non-linear optical system and techniques,” J.W. Nicholson, S. Ramachandran, US Patent 8507877.
  37. “Selectively pumping a gain-doped region of an optical fiber,” D.J. Digiovanni, S. Ramachandran, US Patent 8520299.

 


Prof. Siddharth Ramachandran
ECE Department & Photonics Center, Boston University
8 St. Mary’s Street, Room 521, Boston, MA 02215, USA
Phone: (617) 353-9881, Email: sidr [at] bu [dot] edu