Coherent 16 Quadrature Amplitude Modulation (16QAM) Optical Communication Systems

Coherent optical fiber communications for data rates of 100Gbit/s and beyond have recently been studied extensively primarily because high sensitivity of coherent receivers could extend the transmission distance. Spectrally efficient modulation techniques such as M-ary quadrature amplitude modulation (M-QAM) can be employed for coherent optical links. The integration of multi-level modulation formats based on coherent technologies with wavelength-division multiplexed (WDM) systems is key to meet the aggregate bandwidth demand. This paper reviews coherent 16 quadrature amplitude modulation (16QAM) systems to scale the network capacity and maximum reach of current optical communication systems to accommodate traffic growth. Full Text: PDF ReferencesK. Kikuchi, "Fundamentals of Coherent Optical Fiber Communications", J. Lightwave Technol., vol. 34, no. 1, pp. 157-179, 2016. CrossRef S. Tsukamoto, D.-S. Ly-Gagnon, K. Katoh, and K. Kikuchi, "Coherent Demodulation of 40-Gbit/s Polarization-Multiplexed QPSK Signals with16-GHz Spacing after 200-km Transmission", Proc. OFc, Paper PDP29, (2005). DirectLink K. Kikuchi, "Coherent Optical Communication Technology", Proc. OFC, Paper Th4F.4, (2015). CrossRef J. M. Kahn and K.-P. Ho, "Spectral efficiency limits and modulation/detection techniques for DWDM systems", IEEE J. Sel. Topics Quantum Electron., vol. 10, no. 2, pp. 259–272, (2004). CrossRef S. Tsukamoto, K. Katoh, and K. Kikuchi, "Coherent demodulation of optical multilevel phase-shift-keying signals using homodyne detection and digital signal processing", IEEE Photon. Technol. Lett., vol. 18, no. 10, pp. 1131–1133, (2006). CrossRef Y. Mori, C. Zhang, K. Igarashi, K. Katoh, and K. Kikuchi, "Unrepeated 200-km transmission of 40-Gbit/s 16-QAM signals using digital coherent receiver", Opt. Exp., vol. 17, no. 32, pp. 1435–1441, (2009). CrossRef H. Nakashima, Et al., "Digital Nonlinear Compensation Technologies in Coherent Optical Communication Systems", Proc. OFC, Paper W1G.5, (2017). CrossRef S. J. Savory, "Digital filters for coherent optical receivers", Opt. Exp., vol. 16, no. 2, pp. 804–817, (2008). CrossRef D. S. Millar, T. Koike-Akino, S. Ö. Arık, K. Kojima, K. Parsons, T. Yoshida, and T. Sugihara, "High-dimensional modulation for coherent optical communications systems", Opt. Express, vol. 22, no. 7, pp 8798-8812, (2014). CrossRef R. Griffin and A. Carter, "Optical differential quadrature phase-shift key (oDQPSK) for high capacity optical transmission", Proc. OFC, Paper WX6, (2002). DirectLink K. Kikuchi, "Digital coherent optical communication systems: fundamentals and future prospects", IEICE Electron. Exp., vol. 8, no. 20, pp. 1642–1662, (2011). CrossRef F. Derr, "Optical QPSK transmission system with novel digital receiver concept", Electron Lett., vol. 27, no. 23, pp. 2177–2179, (1991). CrossRef R. No’e, "Phase noise tolerant synchronous QPSK receiver concept with digital I&Q baseband processing", Proc. OECC, Paper 16C2-5, (2004). DirectLink D.-S. Ly-Gagnon, S. Tsukamoto, K. Katoh, and K. Kikuchi, "Coherent detection of optical quadrature phase-shift keying signals with carrier phase estimation", J. Lightw. Technol., vol. 24, no. 1, pp. 12–21, (2006). CrossRef M. Taylor, "Coherent detection method using DSP for demodulation of signal and subsequent equalization of propagation impairments", IEEE Photon. Technol. Lett., vol. 16, no. 2, pp. 674–676, (2004). CrossRef S. Tsukamoto, K. Katoh, and K. Kikuchi, "Unrepeated transmission of 20-Gb/s optical quadrature phase-shift-keying signal over 200-km standard single-mode fiber based on digital processing of homodyne-detected signal for Group-velocity dispersion compensation", IEEE Photon. Technol. Lett., vol. 18, no. 9, pp. 1016–1018, (2006). CrossRef S. Tsukamoto, Y. Ishikawa, and K. Kikuchi, "Optical Homodyne Receiver Comprising Phase and Polarization Diversities with Digital Signal Processing", Proc. ECOC, Paper Mo4.2.1, (2006). CrossRef K. Kikuchi and S. Tsukamoto, "Evaluation of Sensitivity of the Digital Coherent Receiver", J. Lightw. Technol., vol. 20, no. 13, pp. 1817–1822, (2008). CrossRef S. Ishimura and K. Kikuchi, "Multi-dimensional Permutation Modulation Aiming at Both High Spectral Efficiency and High Power Efficiency", Proc. OFC/NFOEC, Paper M3A.2, (2014). CrossRef F. I. El-Nahal and A. H. M. Husein, "Radio over fiber access network architecture employing RSOA with downstream OQPSK and upstream re-modulated OOK data", (Optik) Int. J. Light Electron Opt., vol. 123, no. 14, pp: 1301-1303, (2012). CrossRef T. Koike-Akino, D. S. Millar, K. Kojima, and K. Parsons, "Eight-Dimensional Modulation for Coherent Optical Communications", Proc. ECOC, Paper Tu.3.C.3, (2013). DirectLink B. Sklar, Digital communications: Fundamentals and Applications, Prentice-Hall, (2001).

Unidirectional and bidirectional coupling of surface plasmons based on nonperiodic nano slit array

A 2D structure made up of nano slits to couple free space mode of any given wave front to a propagating Surface Plasmon Polariton (SPP) mode of Metal Insulator Metal (MIM) waveguide is proposed. The structure can be designed to act as either a unidirectional coupler or a bidirectional coupler. Designed structures are simulated using FEM technique and results for circular and plane wave fronts are demonstrated. From the results obtained, it is observed that there is an optimum aperture size for coupling maximum power into the MIM waveguide for the case of circular wave front. Full Text: PDF ReferencesMaier S A, Plasmonics: fundamentals and applications (Springer, Berlin 2007). CrossRef Chen J et al.,"Efficient unidirectional generation of surface plasmon polaritons with asymmetric single-nanoslit", Appl. Phys. Lett. 97, 4 (2010) CrossRef Yang X et al., "Unidirectional generation of surface plasmon polaritons by a single right-angled trapezoid metallic nanoslit", J. Phys. D: Appl. Phys., 50, 4 (2017). CrossRef Lu F et al. "An efficient and ultra-broadband unidirectional optical coupler for wide incidence angles", Opt. Commun., 379 (2016). CrossRef Liu D et al., "New RLL Decoding Algorithm for Multiple Candidates in Visible Light Communication", IEEE Photon. Technol. Lett., 27, 15 (2015). CrossRef Wang C M et al., "Angle-Independent Infrared Filter Assisted by Localized Surface Plasmon Polariton", IEEE Photon. Technol. Lett., 20, 13 (2008). CrossRef Wang C M, Feng D Y, "Omnidirectional thermal emitter based on plasmonic nanoantenna arrays", Opt. Express 22, 2 (2014). CrossRef Huang Y, Min C and Veronis G, "Light trapping by backside diffraction gratings in silicon solar cells revisited", Opt. Express 20, 20 (2012). CrossRef Liang X et al., "Undirectional launcher of surface plasmon polaritons based on subwavelength slits with side-illumination and backside-illumination", Optik 127, 3 (2016). CrossRef Dionne J A, Lezec H J and Atwater H A, "Highly Confined Photon Transport in Subwavelength Metallic Slot Waveguides", Nano letters 6, 9 (2006). CrossRef Ghatak, A., & Thyagarajan, K, An introduction to fiber optics Cambridge university press 1998). CrossRef Vial A et al., "Improved analytical fit of gold dispersion: Application to the modeling of extinction spectra with a finite-difference time-domain method", Phys. Rev. B: Condens. Matter, 71, 8 (2005). CrossRef

Ultra-low material loss microstructure fiber for terahertz guidance

In this letter, we numerically demonstrate a hybrid-core microstructure fiber for low-loss terahertz guidance. Finite element method with circular perfectly matched layer boundary condition is applied to characterize the guiding properties. It is shown that by using a triangular-core inside a square lattice microstructure exhibits ultra-low effective material loss (EML) of 0.169 dB/cm and low confinement loss of 0.087 dB/cm at the operating frequency of 0.75 THz. We also discuss how other guiding properties including power fraction, single mode propagation and dispersion vary with changing of core diameter and operating frequencies. This low-loss microstructure fiber can be effectively used in numerous applications in the THz regime. Full Text: PDF ReferencesJ. J. Bai, J. N. Li, H. Zhang, H. Fang, S. J. Chang, "A porous terahertz fiber with randomly distributed air holes", Appl. Phys. B 103, 2 (2011). CrossRef S. Atakaramians, S. Afshar, B. M. Fischer, D. Abbott, T. M. Monro, "Porous fibers: a novel approach to low loss THz waveguides", Opt. Express 16, 12 (2008). CrossRef K. Wang, D. M. Mittleman, "Metal wires for terahertz wave guiding", Nature 432, 7015 (2004). CrossRef R. Islam, G. K. M. Hasanuzzaman, M. S. Habib, S. Rana, M. A. G. Khan, "Low-loss rotated porous core hexagonal single-mode fiber in THz regime", Opt. Fiber Technol. 24, (2015). CrossRef M. I. Hasan, S. M. A. Razzak, G. K. M. Hasanuzzaman, M. S.Habib, "Ultra-Low Material Loss and Dispersion Flattened Fiber for THz Transmission", IEEE Photon. Technol. Lett. 26, 23 (2014). CrossRef S. F. Kaijage, Z. Ouyang, X. Jin, "Porous-Core Photonic Crystal Fiber for Low Loss Terahertz Wave Guiding", IEEE Photon. Technol. Lett. 25, 15 (2013). CrossRef M. R. Hasan, M. A. Islam, A. A. Rifat, "A single mode porous-core square lattice photonic crystal fiber for THz wave propagation", J. Eur. Opt. Soc. Rapid Publ. 12, 1 (2016). CrossRef M. R. Hasan, M. A. Islam, M. S. Anower, S. M. A. Razzak, "Low-loss and bend-insensitive terahertz fiber using a rhombic-shaped core", Appl. Opt. 55, 30 (2016). CrossRef S. Ali et al. "Ultra-low loss THz waveguide with flat EML and near zero flat dispersion properties", in 9th Int. Conf. on Elect. and Comp. Eng., IEEE, (2016). CrossRef K. Nielsen, H. K. Rasmussen, A. J. Adam, P. C. Planken, O. Bang, P. U. Jepsen, "Bendable, low-loss Topas fibers for the terahertz frequency range", Opt. Express 17, 10 (2009). CrossRef A. W. Snyder, J. D. Love, Optical waveguide theory (London, Chapman & Hall 1983). DirectLink L. Vincetti, A. Polemi, in Antennas and Propagation Society International Symposium, IEEE (2009)G. P. Agrawal, Nonlinear fiber optics (Boston, Academic Press 1989). CrossRef B. S. Williams, "Terahertz quantum-cascade lasers", Nat. Photon. 1, 9 (2007). CrossRef H. W. Hubers et al. "Terahertz quantum cascade laser as local oscillator in a heterodyne receiver", Opt. Express 13, 15 (2005). CrossRef

Exploring the scattering directionality and light interaction in nanoparticle dimers of different semiconductors

Assuming as a starting point our recent work on a dimer of silicon nanoparticles with light scattering directionality, we have explored the light interaction between the incoming and scattered electric fields in dimers made of other different semiconductors. The scattering directionality is achieved by accomplishing Kerker's conditions. By directing the scattered light towards the gap of the dimer, interferential effects can be used to achieve high or low light intensities as a basis of all-optical nanoswitches. A comparison between dimers of different materials is shown. Full Text: PDF ReferencesR. Gómez-Medina, B. García-Cámara, I. Súarez-Lacalle, F. González, F. Moreno, M. Nieto-Vesperias and J.J. Sáenz, "Electric and magnetic dipolar response of germanium nanospheres: interference effects, scattering anisotropy, and optical forces", J. Nanophoton. 5 053512 (2011). CrossRef B. Rolly, B. Stout and N. Bonod, "Boosting the directivity of optical antennas with magnetic and electric dipolar resonant particles", Opt. Express 20 20376 (2012). CrossRef B. García-Cámara, R. Gómez-Medina, J.J. Sáenz, and B. Sepúlveda, "Sensing with magnetic dipolar resonances in semiconductor nanospheres", Opt. Express 21 23007-23020 (2013). CrossRef B. García-Cámara et al., "All-Optical Nanometric Switch Based on the Directional Scattering of Semiconductor Nanoparticles", J. Phys. Chem. C. 119, 19558?19564 (2015). CrossRef A.I. Barreda, H. Saleh, A. Litman, F. González, J-M. Geffrin, and F. Moreno, "Electromagnetic polarization-controlled perfect switching effect with high-refractive-index dimers and the beam-splitter configuration", Nat. Commun. 8, 13910 (2017). CrossRef R. Vergaz et al., "Control of the Light Interaction in a Semiconductor Nanoparticle Dimer Through Scattering Directionality", IEE Phot. Jour., 8(3), 4501410 (2016) CrossRef B. García-Cámara et al., "Size Dependence of the Directional Scattering Conditions on Semiconductor Nanoparticles", IEEE Photon. Technol. Lett. 27(19), 2059?2062 (2015). CrossRef