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  • 1. Abeywickrama, Sandu
    et al.
    Furdek, Marija
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Wong, Elaine
    Protecting core networks with dual-homing: A study on enhanced network availability, resource efficiency, and energy-savings2016Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 381, s. 327-335Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Core network survivability affects the reliability performance of telecommunication networks and remains one of the most important network design considerations. This paper critically examines the benefits arising from utilizing dual-homing in the optical access networks to provide resource-efficient protection against link and node failures in the optical core segment. Four novel, heuristic-based RWA algorithms that provide dedicated path protection in networks with dual-homing are proposed and studied. These algorithms protect against different failure scenarios (i.e. single link or node failures) and are implemented with different optimization objectives (i.e., minimization of wavelength usage and path length). Results obtained through simulations and comparison with baseline architectures indicate that exploiting dual-homed architecture in the access segment can bring significant improvements in terms of core network resource usage, connection availability, and power consumption.

  • 2.
    Aghamiri, Seyed Mohammadreza
    et al.
    Shahid Beheshti University, Department of Radiation Medicine, Tehran, Iran.
    Namedanian, Mahziar
    Shahid Beheshti University, Department of Radiation Medicine, Tehran, Iran.
    Sanjabi, Zahora
    Shahid Beheshti University, Department of Radiation Medicine, Tehran, Iran.
    Effect of gamma irradiation on the light polarization variation of PMMA polymer2008Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 281, nr 3, s. 356-359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analyzing the effect of ionized gamma irradiation on the optical parameters of materials is a solution for finding newer techniques in the field of detector and dosimeter systems. A PMMA (polymethylmethacrylate) polymer was radiated from a 60Co source with a power of 1800 C and a constant dose rate of 1.44 kGy/h in three steps of 5, 25 and 61.2 kGy. The ionized gamma irradiation affected the refractive index of polymer and therefore it changes the polarization of the incident light. The difference in the polarization phase shift of the polymer depended on the dose it had been irradiated with.

  • 3.
    Almlöf, Jonas
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Björk, Gunnar G. E.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    A short and efficient error correcting code for polarization coded photonic qubits in a dissipative channel2011Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 284, nr 1, s. 550-554Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a short and efficient non-degenerate quantum error correcting code that is adapted for qubits encoded on two orthogonal, single-photon states (e.g., horizontally and vertically polarized) subject to a dissipative channel. The proposed code draws its strength from the fact that it is adapted to the physical characteristics of the information-carrying basis states under the action of the channel. The code combines different energy manifolds and consists of only 3 spatio-temporal modes and on average 2 photons per code word.

  • 4.
    Amer, Eynas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Gren, Per
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Sjödahl, Mikael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Stimulated laser induced fluorescence holography for imaging fluorescent species2013Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 311, s. 124-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper pulsed digital holographic detection is coupled to the stimulated laser induced fluorescence (LIF) effect for imaging fluorescent species. A frequency tripled Q-switched Nd-YAG laser (wavelength 355 nm, pulse duration 12 ns) has been used to pump Coumarin 153 dye solved in ethanol. Simultaneously a frequency doubled pulse (532 nm) from the same laser is used to probe the solvent resulting in a gain through stimulated emission. The resulting gain of the probe beam is recorded using digital holography by blending it with a reference beam on the detector. Intensity maps were calculated from the recorded digital holograms and used to calculate the gain of the probe beam due to stimulated fluorescence emission which is coupled to the concentration of the dye. The results show that the amplification of the probe beam (532 nm) due to stimulated LIF emission is seen in the intensity maps. The gain is about 40% at a dye concentration of 0.32 g/L and decreases to be about 20% at a dye concentration of 0.04 g/L for a probe beam energy density of 0.1 mJ/cm2. Spectroscopic measurements have been carried out to confirm the holographic results. The results show that stimulated LIF holography is a promising technique for quantitative imaging of fluorescent species.

  • 5. Banerjee, S.
    et al.
    Rondoni, L.
    Mukhopadhyay, S.
    Misra, Amar P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption2011Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 284, nr 9, s. 2278-2291Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optical chaos is a topic of current research characterized by high-dimensional nonlinearity which is attributed to the delay-induced dynamics, high bandwidth and easy modular implementation of optical feedback. In light of these facts, which add enough confusion and diffusion properties for secure communications, we explore the synchronization phenomena in spatiotemporal semiconductor laser systems. The novel system is used in a two-phase colored image encryption process. The high-dimensional chaotic attractor generated by the system produces a completely randomized chaotic time series, which is ideal in the secure encoding of messages. The scheme thus illustrated is a two-phase encryption method, which provides sufficiently high confusion and diffusion properties of chaotic cryptosystem employed with unique data sets of processed chaotic sequences. In this novel method of cryptography, the chaotic phase masks are represented as images using the chaotic sequences as the elements of the image. The scheme drastically permutes the positions of the picture elements. The next additional layer of security further alters the statistical information of the original image to a great extent along the three-color planes. The intermediate results during encryption demonstrate the infeasibility for an unauthorized user to decipher the cipher image. Exhaustive statistical tests conducted validate that the scheme is robust against noise and resistant to common attacks due to the double shield of encryption and the infinite dimensionality of the relevant system of partial differential equations.

  • 6. Beck, M.
    et al.
    Vogt, Ulrich
    Will, I.
    Liero, A.
    Stiel, H.
    Sandner, W.
    Wilheim, T.
    A pulse-train laser driven XUV source for picosecond pump-probe experiments in the water window2001Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 190, nr 06-jan, s. 317-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe the development of a table top soft X-ray source based on a laser produced plasma. The plasma is produced by a Nd:YLF pulse-train laser which delivers pulse trains of up to 400 pulses each of about 25 ps duration, Number and energy of the micropulses are fully computer controlled adjustable for an optimum interaction with a rotating solid target. Spectral, spatial and temporal characteristics of the X-ray emission from Mylar and copper targets have been studied. A calibrated back-illuminated CCD camera together with a slit grating spectrograph were utilized for the measurement of the absolute soft X-ray photon fluxes. The temporal measurements were performed using a streak camera while the plasma size was measured with a zone plate. An application of the system in a X-ray absorption experiment is shown, The advantages of the system in view of possible optical pump and soft X-ray probe experiments will be discussed.

  • 7.
    Bhaduri, Basanta
    et al.
    National University of Singapore.
    Tay, C.J.
    National University of Singapore.
    Quan, C.
    National University of Singapore.
    Niu, H.
    National University of Singapore.
    Sjödahl, Mikael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Two wavelength simultaneous DSPI and DSP for 3D displacement field measurements2011Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 284, nr 10-11, s. 2437-2440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel optical system is proposed that implements digital speckle pattern interferometry (DSPI) and digital speckle photography (DSP) simultaneously using two wavelength illumination of an object for simultaneous measurement of all three components of the displacement vector field. A collimated red light illuminates both the object and a reference surface in a DSPI configuration which is sensitive to out-of-plane displacement field while a blue light illuminates the object in a DSP configuration which is sensitive to in-plane displacement fields. A color 3-CCD camera records the red and blue lights individually through its red and blue channels, respectively. Two reference images and one image in the deformed state of the object are required for quantitative measurement. Experimental results are presented to validate the system.

  • 8.
    Bjurshagen, Stefan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Koch, R.
    Acreo AB, Kista.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Quasi-three-level Nd:YAG laser under diode pumping directly into the emitting level2006Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 261, nr 1, s. 109-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present theoretical and experimental investigations on ground-state direct pumping at 869 nm into the emitting level F-4(3/2) of end-pumped quasi-three-level Nd:YAG lasers operating at 946 nm. We have demonstrated, what we believe is for the first time, a Nd:YAG laser at 946 nm directly pumped by diodes and obtained 1.6 W of output power.

  • 9.
    Björk, Gunnar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Söderholm, Jonas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Sanchez-Soto, Luis L.
    Klimov, Andrei B.
    Ghiu, Iulia
    Marian, Paulina
    Marian, Tudor A.
    Quantum degrees of polarization2010Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, nr 22, s. 4440-4447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discuss different proposals for the degree of polarization of quantum fields. The simplest approach, namely making a direct analogy with the classical description via the Stokes operators, is known to produce unsatisfactory results. Still, we argue that these operators and their properties should be basic for any measure of polarization. We compare alternative quantum degrees and put forth that they order various states differently. This is to be expected, since, despite being rooted in the Stokes operators, each of these measures only captures certain characteristics. Therefore, it is likely that several quantum degrees of polarization will coexist, each one having its specific domain of usefulness.

  • 10.
    Bogdanski, Jan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ahrens, Johan
    Bourennane, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sagnac quantum key distribution over telecom fiber networks2009Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 282, nr 6, s. 1231-1236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a new concept for compensation of single mode fiber (SMF) birefringence effects in a Sagnac quantum key distribution (QKD) setup, based on a polarization control system and a polarization insensitive phase modulator. Our experimental data show stable (in regards to birefringence drift) QKD over 1550 nm SMF telecom networks in Sagnac configuration, using the BB84-protocol [C.H. Bennett, G. Brassard, in: Proceedings of the IEEE International Conference on Computers, Systems, and Signal Processing, Institute of Electrical and Electronic Engineers, New York, 1984, p. 175] with phase encoding. The achieved total Sagnac transmission loop distances were between 100 km and 150 km with quantum bit error rates (QBER) between 5.84% and 9.79% for the mean-photon-number l = 0.1. The distances were much longer and rates much higher than in any other published Sagnac QKD experiments. We also show an example of our one-decoy state protocol implementations (for the 45 km distance between Alice and Bob, corresponding to the 130 km total Sagnac loop length), providing an unconditional QKD security. The measurement results have showed feasibility of QKD over telecom fiber networks in Sagnac configuration, using standard fiber telecom components.

  • 11.
    Bogdanski, Jan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Rafiei, Nima
    Bourennane, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Multiuser quantum key distribution over telecom fiber networks2009Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 282, nr 2, s. 258-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report five-user quantum key distribution (QKD) over switched fiber networks in both star and tree configurations, using the BB84-protocol [1] with phase encoding. Both setups implement polarization insensitive phase modulators, necessary for birefringent single mode fiber (SMF) networks. In both configurations we have achieved transmission distances between 25 km and 50 km with quantum bit error rates between 1.24% and 5.56% for the mean photon number l ¼ 0:1. The measurements have showed feasibility of multiuser QKD over switched fiber networks, using standard fiber telecom components.

  • 12.
    Cai, Yangjian
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Ge, Di
    Analytical formula for a decentered elliptical Gaussian beam propagating in a turbulent atmosphere2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 271, nr 2, s. 509-516Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analytical formulas for the average intensity and decentered parameter of a decentered elliptical Gaussian beam (DEGB) propagating in a turbulent atmosphere are derived in a tensor form. The propagation properties of a DEGB in a turbulent atmosphere are investigated in detail, and found to be different from that in free space. Furthermore, as an application example, we investigate the propagation of a decentered elliptical flat-topped beam (DEFB) by expressing its electric field as a finite sum of DEGBs in a turbulent atmosphere. The properties of a DEGB or a DEFB in a turbulent atmosphere are closely related with the beam's parameters and the structure constant of the turbulent atmosphere.

  • 13.
    Cai, Yangjian
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Zhang, Lei
    Propagation of a hollow Gaussian beam through a paraxial misaligned optical system2006Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 265, nr 2, s. 607-615Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on the generalized diffraction integral formula for treating the propagation of a laser beam through a paraxial misaligned optical system in the cylindrical coordinate system, we obtain an analytical formula for a hollow Gaussian beam passing through a paraxial misaligned optical system. Furthermore, we also obtain the approximate analytical formula for a hollow Gaussian beam passing through a paraxial circularly apertured misaligned optical system by expanding the hard aperture function into a finite sum of complex Gaussian functions. As a numerical example, the propagation properties a hollow Gaussian beam through a misaligned thin lens are studied numerically.

  • 14. Chamaillard, K.
    et al.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Dainty, Chris
    Coherency matrix description for statistical linear regression of Stokes parameters in rough small-particle scattering2010Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, nr 22, s. 4519-4524Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A statistical analysis of the Stokes parameters in light scattering by randomly rough small particles shows a linear regression law between the squares of the first two components I-s and Q(s) of the Stokes vector. While the coefficients of this linear regression contain physical characteristics of the particles, they cannot be directly interpreted in terms of the degree of polarization of the scattered field. We propose an interpretation of this relationship between the Stokes parameters on the basis of the general coherence-density matrix formalism. The link between the statistical regression results and the polarization properties of the stochastic scattered components of the field is established through the coherency matrix elements.

  • 15. Chen, R.
    et al.
    Wang, M.
    Wang, S.
    Liang, Hao
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Hu, X.
    Sun, X.
    Zhu, J.
    Ma, L.
    Jiang, M.
    Hu, J.
    Li, J.
    A low cost surface plasmon resonance biosensor using a laser line generator2015Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 349, s. 83-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to the instrument designed by using a common surface plasmon resonance biosensor is extremely expensive, we established a portable and cost-effective surface plasmon resonance biosensing system. It is mainly composed of laser line generator, P-polarizer, customized prism, microfluidic cell, and line Charge Coupled Device (CCD) array. Microprocessor PIC24FJ128GA006 with embedded A/D converter, communication interface circuit and photoelectric signal amplifier circuit are used to obtain the weak signals from the biosensing system. Moreover, the line CCD module is checked and optimized on the number of pixels, pixels dimension, output amplifier and the timing diagram. The micro-flow cell is made of stainless steel with a high thermal conductivity, and the microprocessor based Proportional-Integral-Derivative (PID) temperature-controlled algorithm was designed to keep the constant temperature (25 °C) of the sample solutions. Correspondingly, the data algorithms designed especially to this biosensing system including amplitude-limiting filtering algorithm, data normalization and curve plotting were programmed efficiently. To validate the performance of the biosensor, ethanol solution samples at the concentrations of 5%, 7.5%, 10%, 12.5% and 15% in volumetric fractions were used, respectively. The fitting equation ΔRU=-752987.265+570237.348×RI with the R-Square of 0.97344 was established by delta response units (ΔRUs) to refractive indexes (RI). The maximum relative standard deviation (RSD) of 4.8% was obtained. 

  • 16. Dai, D. X.
    et al.
    He, Sailing
    Novel ultrasmall Si-nanowire-based arrayed-waveguide grating interleaver with spirals2008Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 281, nr 13, s. 3471-3475Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel layout is presented to achieve an ultrasmall arrayed-waveguide grating (AWG) interleaver based on Si-nanowire waveguides. Spiral waveguides are inserted in the middle of arrayed-waveguide to obtain a large lightpath (required for the ultra-high diffraction order) in a small occupied area. A designed ultrasmall AWG interleaver with a free spectral range of 0.8 nm has a total size of only about 73 mu m x 372 mu m (0.027 mm(2)).

  • 17. Dai, D. X.
    et al.
    Liu, L.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Analysis of integrated corner mirrors by using a wide-angle beam propagation method2006Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 260, nr 2, s. 733-740Artikel i tidskrift (Refereegranskat)
  • 18. Dai, D. X.
    et al.
    Mei, W. Q.
    He, Sailing
    KTH, Tidigare Institutioner                               , Teoretisk elektroteknik.
    Using a tapered MMI to flatten the passband of an AWG2003Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 219, nr 01-6, s. 233-239Artikel i tidskrift (Refereegranskat)
  • 19. Dai, Daoxin
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Highly-sensitive sensor with large measurement range realized with two cascaded-microring resonators2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 279, nr 1, s. 89-93Artikel i tidskrift (Refereegranskat)
  • 20.
    Dai, Daoxin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Reduction of multimode effects in an SOI-based etched diffraction grating demultiplexer2005Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 247, nr 4-6, s. 281-290Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multimode effects in the free propagation region (FPR) of a silicon-on-insulator (SOI)-based etched diffraction grating (EDG) demultiplexer are analyzed. In a conventional design, the power coupled to the higher order modes is considerable, which introduces a significant excess loss and crosstalk. It is shown that the multimode effects in an SOI EDG demultiplexer are much more detrimental than in an arrayed waveguide grating demultiplexer. Several methods for reducing the multimode effects are discussed. In particular, a laterally tapered structure between the FPR and the input/output waveguides is proposed as a simple and effective method for reducing the power coupled to the higher order modes and consequently reducing the multimode effects. The taper width is optimized to minimize the crosstalk.

  • 21.
    Dai, Daoxin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Liu, Liu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Three-dimensional hybrid modeling based on a beam propagation method and a diffraction formula for an AWG demultiplexer2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 270, nr 2, s. 195-202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An efficient and accurate three-dimensional (3D) hybrid modeling, which combines a 3D beam propagation method (BPM) and the two-dimensional (2D) Kirchhoff-Huygens diffraction formula, is developed to simulate the field propagation in an arrayed waveguide grating (AWG) dernultiplexer. The 2D Kirchhoff-Huygens diffraction formula is used for the simulation of the light propagation in the free propagation regions (FPRs). A 3D BPM in a polar coordinate system is used to simulate the light propagation in the transition region between the input FPR and the arrayed waveguides so that the coupling coefficients for the arrayed waveguides are calculated conveniently and accurately. For the simulation in the transition region between the arrayed waveguides and the output FPR, only the central arrayed waveguide and several adjacent ones are needed in the computational window of a standard BPM and thus the computation efficiency is improved. Finally, a flat-top AWG is designed and fabricated to verify the reliability of the present simulation method. The calculated and measured spectral responses are in a good agreement.

  • 22.
    Dainese, Matteo
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Directional coupler wavelength selective filter based on dispersive  Bragg Reflection Waveguide2006Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 260, nr 2, s. 514-521Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new type of wavelength selective filter, based on high differential dispersion between two coupled waveguides, is presented. The Bragg Reflection Waveguide displays high effective refractive index dispersion, due to the interaction of the guided mode with the two confining Bragg reflectors. When coupled with a weakly guided buried channel silica waveguide, a very narrow bandwidth filter (< 1 nm) can be easily produced, in a shorter length, with respect to directional couplers made with standard step index channel waveguides. The complete design methodology, fabrication and characterization are presented.

  • 23. deMatos, C J S
    et al.
    Margulis, W
    RISE., Swedish ICT, Acreo.
    Optical fibre modulator based on electrostatic attraction2001Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 190, nr 1, s. 135-Artikel i tidskrift (Refereegranskat)
  • 24.
    Denker, Boris
    et al.
    A.M.Prokhorov General Physics Institute, Moscow.
    Galagan, Boris
    A.M.Prokhorov General Physics Institute, Moscow.
    Osiko, V.
    A.M.Prokhorov General Physics Institute, Moscow.
    Sverchkov, S.
    A.M.Prokhorov General Physics Institute, Moscow.
    Balbashov, A.
    Moscow Power Engineering Institute.
    Hellström, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Yb3+,Er3+:YAG at high temperatures: energy transfer and spectroscopic properties2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 271, nr 1, s. 142-147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy transfer and spectroscopic properties at high temperatures have been investigated in Er,Yb:YAG crystals. It is shown that at elevated temperatures around 600-800 degrees C these characteristics become similar to those in the efficient 1.5 mu m laser medium - Er,Yb-doped phosphate glasses. (c) 2006 Elsevier B.V. All rights reserved.

  • 25.
    Dong, Hui
    et al.
    Nanyang Techbological University, Singapore.
    Shum, Ping
    Nanyang Techbological University, Singapore.
    Yan, Min
    Nanyang Techbological University, Singapore.
    Zhou, Junqiang
    Ning, Guoxiang
    Gong, Yandong
    Wu, Chongqing
    Measurement of Mueller matrix for an optical fiber system with birefringence and polarization-dependent loss or gain2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 274, nr 1, s. 116-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In an optical fiber system with both birefringence and polarization-dependent loss or gain (PDL/G), a set of input polarization states and their corresponding outputs are deduced to fulfill some general relationships in Stokes space, by considering the fact that the Mueller matrix of such an optical fiber system meets Lorentz transformation. Then, it can be proven that the minimum number of input polarization states is three for an explicit determination of such a Mueller matrix and no independent input parameter is redundant. Based on the theoretical findings, a general and simple approach is proposed to measure the Mueller matrix. The requirements regarding the choices of three inputs are presented for achieving optimum measurement stability and accuracy. Experimental results on an optical fiber system, formed by two 10-km long single-mode fibers with an optical isolator in between, show excellent agreement with the theory.

  • 26. Drummond, Miguel V.
    et al.
    Nogueira, Rogerio N.
    Violas, Manuel
    Monteiro, Paulo P.
    Sterner, Carola
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Fonjallaz, Pierre-Yves
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    All-optical generation of 40 Gb/s single sideband signals using a fiber Bragg grating2010Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, nr 12, s. 2492-2495Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we demonstrate a reliable all-optical technique for performing optical double sideband (ODSB) to single sideband (OSSB) format conversion of a 40 Gb/s non-return-to-zero signal. It is based on the optimization of a detuned optical filter, which was implemented on a fiber Bragg grating (FBG) with a complex apodization profile. An OSSB signal with negligible distortion was obtained, as the FBG presented a nearly ideal frequency response. Higher tolerance to chromatic dispersion enabled by the OSSB signal in comparison to the ODSB signal was demonstrated on both simulation and experimental results. (C) 2010 Elsevier B.V. All rights reserved.

  • 27.
    Friberg, Ari T.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Turunen, Jari
    Univ Eastern Finland, Dept Math & Phys, FI-80101 Joensuu, Finland..
    Optics communications special issue "electromagnetic coherence and polarization"2010Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, nr 22, s. 4423-4426Artikel i tidskrift (Övrigt vetenskapligt)
  • 28.
    Friberg, Ari T.
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Visser, T. D.
    Wang, W.
    Wolf, E.
    Focal shifts of converging diffracted waves of any state of spatial coherence2001Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 196, nr 06-jan, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We analyze the focusing of wave fields of any state of coherence by systems with low Fresnel numbers. We study the optical intensity on the axis in the focal region. The dependence of the focal shift and of the maximum on-axis intensity on the state of coherence is examined for some model fields.

  • 29. Fu, H. Y.
    et al.
    Ou, H. Y.
    Zhu, K.
    Remb, E.
    He, Sailing
    A tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium2008Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 281, nr 22, s. 5550-5554Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium is proposed, theoretically discussed and experimentally demonstrated. A single-wavelength LD and a modulator (either a Mach-Zehnder modulator or a phase modulator which can avoid the do bias drift problem) are used to obtain a multi-wavelength optical source. By adjusting the modulation frequency and the bias voltage on the modulators, the wavelength spacing and the relative amplitude of the optical tones change, thus making the filter tunable and reconfigurable. The experimental results show that the proposed filters have good tunability and reconfigurability and the mainlobe-to-sidelobe ratio of around 25 dB is achieved.

  • 30. Gong, Y.
    et al.
    Yang, B.
    Zhang, D.
    Hong, X.
    Lu, Y.
    He, Sailing
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. South China Normal University, Guangzhou, China.
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). South China Normal University, Guangzhou, China.
    Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks2018Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 426, s. 151-157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes a crosstalk-aware passive optical interconnect architecture based on multiple arrayed waveguide gratings (AWGs). With two-stage cascaded AWGs, it can realize the communications not only within but also among the clusters for large-scale datacenters. To overcome serious crosstalk in multiple-AWG based optical interconnects, crosstalk suppression schemes are proposed. Proof-of-concept experiments are carried out to verify the necessity and feasibility of the proposed crosstalk suppression schemes for multiple-AWG based optical interconnects.

  • 31. Han, Zhanghua
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Multimode interference effect in plasmonic subwavelength waveguides and an ultra-compact power splitter2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 278, nr 1, s. 199-203Artikel i tidskrift (Refereegranskat)
  • 32. Hong, Y.
    et al.
    Hong, Xuezhi
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation2017Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 383, s. 478-484Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.

  • 33.
    Högström, Herman
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ribbing, Carl Gustaf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    On the angular dependence of gaps in 1-D Si/SiO2 periodic structures2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 271, nr 1, s. 148-153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A multilayer of silicon and silicon dioxide was used to study the angular dependence of reflectance maxima originating from interference and bulk optical properties. Silicon dioxide has a lattice resonance in the infrared causing an interval of high reflectance for wavelengths around 9 μm. The multilayer was designed such that the interference maxima do not overlap/interact with the material related reflectance maximum. In this way the different angular behavior for the two types of reflectance maxima can be studied simultaneously. Experimental and calculated reflectance spectra for s- and p-polarized light for angles of incidence between 0° and 90° collected for every 5° are presented. The reflectance features caused by interference generally move to shorter wavelengths with increasing angle of incidence, and the materials related peak is widened for (s-polarized light) and excitation of the longitudinal modes was observed for p-polarized light.

  • 34.
    Islam, A. B. M. Hamidul
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Very low input voltage cascaded travelling wave electroabsorption modulator (CTWEAM) for more than 100 Gbps2013Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 297, s. 43-47Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the large signal modeling and simulation of two segmented travelling wave electroabsorption modulators (TWEAM) as a cascaded TWEAM (CTWEAM) structure. It will be demonstrated that a mushroom shaped mesa structure with low series resistance (0.69 Omega-mm) will have 3 dB bandwidth more than sufficient for 100 Gbps operation. For a CTWEAM device with 990 lam active segment length, 1.1 V bias voltage and only 0.4 V peak-to-peak (Vp-p) modulating voltage has a bandwidth of 110 GHz, extinction ratio >4 dB and flat frequency response. This device would be an attractive candidate for short distance optical fiber communication as well as long distance telecommunication at 0.4 Vp-p and 1 Vp-p input RF signal, respectively.

  • 35.
    Jalali-Roudsar, Amir Abbas
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Faraday rotation in two-dimensional magneto-optic photonic crystal2005Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 253, nr 1-3, s. 145-150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the enhancement of Faraday rotation in a two-dimensional square-lattice magneto-optic photonic crystal at optical wavelengths. We show that on incidence of a TM plane wave onto the magneto-optic photonic crystal, high TM-TE mode conversion takes place in the transmission bands of TM and TE fields. The photonic crystal structure increases the average wave path length, which in turn leads to a growth in the polarization rotation. We also show that associated with this phenomenon is a widening of the photonic crystal transmission band.

  • 36.
    Jaroszewicz, Zbigniew
    et al.
    Institute of Applied Optics, Warsaw.
    Burvall, Anna
    National University of Ireland, Galway.
    Goncharov, Alexander
    National University of Ireland, Galway.
    Kolacz, Katarzyna
    Institute of Applied Optics, Warsaw.
    Spheric long-focal-depth lens: a comment2008Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 281, nr 19, s. 4849-4850Artikel i tidskrift (Refereegranskat)
  • 37.
    Johansson, Sandra
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Hansson, Renee
    Ekvall, Katrin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laser diode beam shaping with GRIN lenses using the twisted beam approach and its application in pumping of a solid-state laser2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 274, nr 2, s. 403-406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a novel beam shaping method for laser diodes based on the concept of twisted Gaussian Schell-model beams using GRIN lenses. This method enables a more symmetric pump as well as a compact setup for pumping of solid-state lasers. In the experiment with a standard 2 W diode, the beam quality factors in the two orthogonal directions were equalized to M-x(2) approximate to 24 and M-y(2) approximate to 18, respectively, which pumped an intra-cavity frequency-doubled Nd:YAG laser at 946 run with an output of 28 mW at 473 nm.

  • 38. Jonsson, Jacob C.
    et al.
    Brandén, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för teknisk databehandling. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    Obtaining the bidirectional transmittance distribution function of isotropically scattering materials using an integrating sphere2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 277, s. 228-236Artikel i tidskrift (Refereegranskat)
  • 39.
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Boundary symmetries in linear differential and integral equation problems applied to the self-consistent Green's function formalism of acoustic and electromagnetic scattering2006Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 265, nr 2, s. 383-393Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Explicit symmetry relations for the Green's function subject to homogeneous boundary conditions are derived for arbitrary linear differential or integral equation problems in which the boundary surface has a set of symmetry elements. For corresponding homogeneous problems subject to inhomogeneous boundary conditions implicit symmetry relations involving the Green's function are obtained. The usefulness of these symmetry relations is illustrated by means of a recently developed self-consistent Green's function formalism of electromagnetic and acoustic scattering problems applied to the exterior scattering problem. One obtains explicit symmetry relations for the volume Green's function, the surface Green's function, and the interaction operator, and the respective symmetry relations are shown to be equivalent. This allows us to treat boundary symmetries of volume-integral equation methods, boundary-integral equation methods, and the T matrix formulation of acoustic and electromagnetic scattering under a common theoretical framework. By specifying a specific expansion basis the coordinate-free symmetry relations of, e.g., the surface Green's function can be brought into the form of explicit symmetry relations of its expansion coefficient matrix. For the specific choice of radiating spherical wave functions the approach is illustrated by deriving unitary reducible representations of non-cubic finite point groups in this basis, and by deriving the corresponding explicit symmetry relations of the coefficient matrix., The reducible representations can be reduced by group-theoretical techniques, thus bringing the coefficient matrix into block-diagonal form, which can greatly reduce ill-conditioning problems in numerical applications. (c) 2006 Elsevier B.V. All rights reserved.

  • 40. Karlsson, G.
    et al.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    Tellefsen, J. A.
    Q-switching of an Er-Yb: glass microchip laser using an acousto-optical modulator2003Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 217, nr 06-jan, s. 317-324Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a compact Q-switched Er-Yb:glass microchip laser operating at the wavelength of 1.535 mum using an acousto-optical modulator. A Q-switched peak power of 325 W with a pulse-duration of 38 ns and a pulse-to-pulse jitter of less then 10 ns was achieved. Well-controlled pulses were obtained for repetition rates up to 10 kHz while the maximum pulse energy was 12 muJ. The experimental results are compared with theoretical analysis, which shows how to optimize the laser as well as fundamental limitations.

  • 41.
    Khan, Salman Naeem
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Dai, Daoxin
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Liu, Liu Ming
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Optimal design for a flat-top AWG demultiplexer by using a fast calculation method based on a Gaussian beam approximation2006Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 262, nr 2, s. 175-179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Passband broadening of an AWG (array waveguide grating) demultiplexer with an MMI (multimode interference) coupler connected at the end of a tapered input waveguide is considered. An explicit formula based on the field propagation of an approximate Hermit-Gaussian beam is used to calculate quickly and reliably the spectral response of the AWG demultiplexer. The widths of the input waveguide, the output waveguides and the MMI coupler are optimized. The optimal design is verified with the experimental measurement.

  • 42. Lebedev, A
    et al.
    Vegas Olmos, JJ
    Pang, X
    RISE., Swedish ICT, Acreo.
    Tafur Monroy, I
    Larsen, K
    Forchhammer, S
    Low complexity source channel coding for mm-wave hybrid fiber-wireless links2014Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 318, s. 142-Artikel i tidskrift (Refereegranskat)
  • 43. Lee, Hwang Woon
    et al.
    Lee, Kwangjin
    Cho, Sunghun
    Anthony, John Kiran
    Lee, Soonil
    Lim, Hanjo
    Kim, Kihong
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Rotermund, Fabian
    Evaluation of the third-order optical nonlinearity of Au:SiO2 nanocomposites in the off-resonant spectral region2013Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 286, s. 347-352Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The third-order nonlinear optical susceptibility (chi((3))) of Au:SiO2 nanocomposite films with different Au particle sizes was measured to be on the order of 10(-10) esu to 10(-9) esu in the off-resonant spectral region, and the particle size-dependent behavior of chi((3)) was observed. The results were found to deviate substantially from those of the conventional Maxwell-Garnet theory. By adapting the modified invariant imbedding method, which takes into account the effect of interparticle interactions on the nonlinear response, we successfully explain the enhanced third-order nonlinear susceptibility of metal-dielectric nanocomposites at off-resonant wavelengths.

  • 44. Li, J. S.
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Broadband traveling-wave modulator based on Si2N2O substrate2005Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 254, nr 04-6, s. 236-241Artikel i tidskrift (Refereegranskat)
  • 45.
    Lin, Rui
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. Huazhong University of SciandTech (HUST), China.
    Feng, Z.
    Tang, M.
    Wang, R.
    Fu, S.
    Shum, P.
    Liu, D.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. South China Normal University, China.
    Palm-shaped spectrum generation for dual-band millimeter wave and baseband signals over fiber2016Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 367, s. 137-143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to offer abundant available bandwidth for radio access networks satisfying future 5G requirements on capacity, this paper proposes a simple and cost-effective palm-shaped spectrum generation scheme that can be used for high capacity radio over fiber (RoF) system. The proposed scheme can simultaneously generate an optical carrier used for upstream and two bands of millimeter wave (MMW) that are capable of carrying different downstream data. The experiment results show that the proposed palm-shaped spectrum generation scheme outperforms optical frequency comb (OFC) based multi-band MMW generation in terms of upstream transmission performance. Furthermore, simulation is carried out with different dual-band MMW configurations to verify the feasibility of using the proposed spectrum generation scheme in the RoF system.

  • 46.
    Lin, Rui
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). Huazhong University of Sci&Tech (HUST), China.
    Szczerba, K.
    Agrell, E.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Liu, D.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Scalability analysis methodology for passive optical interconnects in data center networks using PAM2017Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 403, s. 283-289Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A framework is developed for modeling the fundamental impairments in optical datacenter interconnects, i.e., the power loss and the receiver noises. This framework makes it possible, to analyze the trade-offs between data rates, modulation order, and number of ports that can be supported in optical interconnect architectures, while guaranteeing that the required signal-to-noise ratios are satisfied. To the best of our knowledge, this important assessment methodology is not yet available. As a case study, the trade-offs are investigated for three coupler-based top-of-rack interconnect architectures, which suffer from serious insertion loss. The results show that using single-port transceivers with 10 GHz bandwidth, avalanche photodiode detectors, and quadratical pulse amplitude modulation, more than 500 ports can be supported.

  • 47. Lindberg, J.
    et al.
    Setala, T.
    Kaivola, M.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Coherence and polarization properties of a three-dimensional, primary, quasi-homogeneous, and isotropic source and its far field2010Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, nr 22, s. 4452-4456Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the spatial coherence properties of a three-dimensional, primary, quasi-homogeneous, and isotropic source and the far field that it generates. We assess the spectrum, degree of polarization, electromagnetic degree of coherence, and effective degree of coherence of the source and of the far field. We also demonstrate the formalism for a spherical Gaussian Schell-model current source. The polarization properties of light are fully accounted for in the analysis, and it is found that certain results pertaining to scalar coherence theory are reproduced also within the electromagnetic treatment.

  • 48.
    Liu, Liu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Han, Z.
    Forsberg, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Ultra-compact Directional Couplers and Mach-Zehnder Interferometers employing Surface Plasmon Polaritons2005Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 259, nr 2, s. 690-695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optical directional couplers and Mach-Zehnder interferometers employing surface plasmon polaritons are proposed and their characteristics are analyzed numerically using a finite-difference time-domain method. It is shown that these devices can have transverse size smaller than the incident wavelength and can then be regarded as true subwavelength photonic elements. The ultra-compact characteristic of these devices can be utilized as a basis of next generation of integrated photonic circuits. Furthermore, calculations also show that these devices behave differently from their traditional all-dielectric counterparts. For the proposed optical directional coupler, the phase difference between the two output ports will no longer be 90 degrees even when the two ports have the same power outputs.

  • 49. Lu, Xiang
    et al.
    Cai, Yangjian
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Analytical formulas for a circular or non-circular flat-topped beam propagating through an apertured paraxial optical system2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 269, nr 1, s. 39-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Propagation of a flat-topped beam of circular or non-circular (rectangular or elliptical) symmetry through an apertured optical system is investigated. By expanding the hard aperture function as a finite sum of complex Gaussian functions, some approximate analytical propagation formulas are derived for a flat-topped beam of circular or non-circular (rectangular or elliptical) symmetry propagating through an apertured paraxial general astigmatic (GA) optical system or an apertured paraxial misaligned stigmatic (ST) optical system. The derived formulas are very fast to compute. The results obtained by using the approximate analytical expressions are in a good agreement with those obtained by direct numerical integration. The present analytical formulas provide a convenient and effective way for studying the propagation and transformation of a circular or non-circular flat-topped beam through an apertured general optical system.

  • 50.
    Lu, Yang
    et al.
    KTH. Hangzhou Dianzi University, China.
    Bi, M.
    Hu, M.
    Wei, Y.
    Yang, G.
    Zhou, X.
    Li, Q.
    Orthogonal modulation application to achieve flexible migration and colorless ONUs for next generation PON2017Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 403, s. 252-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Flexible migration that reuse the deployed infrastructure and colorless ONUs which avoid inventory problem are two major challenges of next-generation passive optical network (NGPON). In this paper, flexible migration is achieved by the coexistence of legacy PON and NGPON and colorless ONUs is achieved by upstream remodulation. Orthogonal modulation methods such as DPSK, PolSK and WSK are applied for NGPON downstream signal to ensure the constant amplitude. The amplitude-constant NGPON downstream signal induces low crosstalk to the coexisting legacy PON signal and the remodulated upstream signal. The experimental demonstration shows error free transmission and verifies the feasibility of the proposed scheme.

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