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Transparent Optical Networks, 2003. Proceedings of 2003 5th International Conference on

Date 29 June-3 July 2003

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  • Wide angle oblique beam propagation

    Page(s): 26 - 29 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    The properties of wide-angle beam propagation in oblique coordinate system are studied. The wide angle algorithm is compared with the standard paraxial one and with the beam propagation in the rectangular coordinate system. The results obtained by the new algorithm are consistent with the ones given by the standard rectangular Beam Propagation Method. It is found that when the local waveguide geometry does not match the local coordinate system used to describe it the wide-angle algorithm is sensitive to staircasing. View full abstract»

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  • Physics and design of low noise avalanche photodiodes - LEOS distinguished lecture 2003-2004

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    Summary form only given. Avalanche photodiodes (APDs) are used in many applications when conventional unity gain photodiodes cannot provide enough sensitivity and the extra amplification provided by the impact ionization process gives it an advantage. Unfortunately this amplification or gain of the incoming optical signal is always accompanied by some 'excess noise' due to the stochastic nature of the ionization process and this sets a limit to the maximum useful gain. Early work by McIntyre showed that the excess noise depended on the ratio of hole ionization coefficient (β) to electron ionization coefficient (α). α and β are semiconductor material dependent and unfortunately most III-V materials have α≈β, giving rise to relatively high excess noise. Since the ionization coefficients depend on the details of the band structure it is extremely difficult to modify, even using band-gap engineering techniques such as superlattices or MQWs. In recent years, work done at the University of Sheffield and the University of Texas (Austin) has shown that low excess noise can be obtained in homojunction structures simply by utilising thin avalanching regions. Experimental results show that contrary to conventional theory, the excess noise actually decreases as the avalanching width reduces. This behaviour has now been observed in virtually all semiconductor materials including GaAs, AlGaAs, InP, AlInAs and even silicon. The reason for this anomalous behaviour in thin devices is due to the 'dead space' (d), defined as the minimum distance a carrier has to travel before it is in equilibrium with the electric field. Conventional models of the ionization process ignored. This assumption is generally valid in devices with thick avalanching widths in which the dead space distance, d, is relatively small compared to the avalanching width, w. In thin avalanching width structures, d becomes a significant fraction of w and the ionizing process becomes more deterministic, reducing the stochastic variations that give rise to the excess noise. This talk will review these results and show that in addition to reducing the excess noise, thin avalanching widths offer APDs with other advantages such as lower operating vo- ltages, better temperature stability and predicted enhanced speed of operation. View full abstract»

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  • Optical modulation formats for high-speed DWDM systems

    Page(s): 162 - 165 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    State-of-the-art of high-capacity optical modulation formats used in high-speed DWDM transmission systems are presented. Simulations of 320 km transmission of DWDM signal show that DQPSK modulation is superior to CS-RZ (carrier-suppressed return-to-zero) and duobinary phase modulation with respect to signal degradation due to Kerr nonlinearities. View full abstract»

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  • Stabilising the Du Fort Frankel beam propagation scheme for modelling lossy structures

    Page(s): 22 - 25 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB) |  | HTML iconHTML  

    The Du Fort Frankel beam propagation method is an explicit three level scheme that is ideally suited to parallel computing. In the case of media without loss or gain, the scheme is conditionally stable allowing relatively large propagation steps, however in the presence of loss or gain it is always unstable. A stabilised Du Fort Frankel scheme is presented that extends the scope of this powerful method to cover these practically important scenarios. View full abstract»

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  • Cost effective transparent long-distance interconnection of metropolitan networks over ultra-long-haul optical links

    Page(s): 64 - 68 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB) |  | HTML iconHTML  

    In transparent optical networks, all data rates and formats can be transmitted simultaneously and the number of transponders, as the main driver of network costs, can be reduced significantly. High flexibility and an effective optical 1:N-protection can be implemented by configurable passive optical add-drop-multiplexers. We performed field experiments to interconnect metropolitan and long haul optical networks transparently. View full abstract»

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  • A comparison of inner coding options for adaptive MIMO OFDM systems

    Page(s): 141 - 144 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (434 KB) |  | HTML iconHTML  

    Some novel results concerning adaptive space-time-frequency coding schemes for MIMO OFDM systems are illustrated. In the proposed concatenated schemes, a conventional convolutional encoder is followed by a bit-wise interleaver and an inner orthogonal space-time encoder in order to exploit the space/frequency diversity provided by the frequency selective MIMO channel. Adaptivity can be implemented by adjusting the constellation size on a subcarrier by subcarrier basis by means of standard bit/energy-loading algorithms for SISO channels. An extension of the transmit selection diversity (TSD) technique for the two transmit/receive antenna scenario is also considered as an alternative to the inner ST code. View full abstract»

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  • Lorentz transformations in beam polarization optics

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    Summary form only given. In beam optics, polarization properties of beams can be alternatively described by a vector of the four stokes parameters, by the two-by-two polarization matrix, or by the two, in general, Jones vectors in two-dimensional polarization space. The evolution of the beam along an optical system is then given, in paraxial approximation, with the aid of the Mueller four-by-four matrices or the Jones two-by-two matrices. On the other hand, in the special theory of relativity, we deal with the space-time four-vectors, second-rank spinor matrices or with the two-dimensional spinor vectors. All these entities are transformed under four-dimensional and two-dimensional representations of the restricted six-parameter Lorentz group, respectively. Although these transformations are of different origin in both cases, the Lorentz invariance of a space-time interval in the coordinate, Minkowski space corresponds to the invariance of a polarization degree of the transforming beam. Basic features of the above correspondence are reviewed and a few examples of the Lorentz transformations of the coherent beam polarization are given. Some aspects of this correspondence, not considered in this context in the literature until very recently, are outlined. It is shown that the invariance of the beam polarization transformations specifies a definition of beam amplitude, with transformation properties independent of those related to the beam polarization. A suitable reference frame for the treatment of the beam amplitude and the beam polarization is proposed. A case of the beam transformations at a dielectric interface is discussed in more detail. This leads to a complete identification between scattering coefficients of a multilayer optical structure and the parameters of the corresponding Lorentz transformation. View full abstract»

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  • Numerical simulation reflectometry measurements of optical fibre parameters

    Page(s): 152 - 154 vol.2
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    Monte-Carlo method is used for the reflectograms simulation in optic fibre. Two type of inhomogeneousness take into the point in the calculations - local and distributed. View full abstract»

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  • Design of automatically switched optical networks

    Page(s): 125 - 128 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (669 KB) |  | HTML iconHTML  

    Due to the advances in optical component technology and the desired integration of the technological network layers, more significant professional attention is being paid to the concept and the emerging technology of automatically switched optical networks (ASON). The intelligent switching capabilities enable more dynamic networking, which may change the network characteristics significantly. The study of these changing characteristics is required in order to provide a firm basis for strategic network development decisions. After a brief overview of the ASON technology, the paper illustrates the potential advantages and drawbacks due to the dynamic behavior of the optical network. The analysis of numerical results from small network examples helps to highlight the main networking features of dynamic provisioning of optical channels. Based on the results of network simulations, a comparison of semi-permanent and switched connection based services is performed, taking into account different source activities. Finally, a quantitative analysis is given of the expected network resource savings originating from the statistical gains of automatic switching. View full abstract»

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  • Super-channel architectures for in-service capacity expansion of CWDM/DWDM systems

    Page(s): 84 - 86 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    Super-channel architectures enable many narrow spaced wavelengths to be nested into one CWDM (coarse WDM) or DWDM channel at the rates up to 10 Gb/s. This gives a low-cost, growth on demand, capacity upgrades as an overlay to existing CWDM/DWDM systems. View full abstract»

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  • Challenges of optical access networks

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    Summary form only given. Broadband access and in-house networks are prerequisites for both business and private customers for future multimedia Internet communication. Current solutions for providing capacities of more than 100 Mbit/s to residential customers and up to several gigabits per second to business customers and enterprises are too expensive in both installation and operation, and are not ready for volume production. As potential candidates for overcoming cost barriers, WDM based solutions of optical access networks are the main focus of this contribution, where aspects of cost-efficiency, simplicity, versatility, and practical issues of installation and introduction are addressed. Moreover, recent developments in the optical access network domain are touched, and the customer's need for short period high-speed transmission capacity is illustrated. View full abstract»

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  • The pumping of double-clad neodymium fiber

    Page(s): 145 - 147 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (371 KB) |  | HTML iconHTML  

    The paper presents a new method of pumping lasers built on the basis of double-clad neodymium-ion doped lasers. The asymmetrical couplers were realized by grinding and built on a multi-mode PCS (pumping) fiber and a double-clad (pumped) fiber. Special software for designing such asymmetrical couplers was elaborated. It allows us to choose appropriate parameters of the coupler's elements, enabling us to obtain a maximum pumping power, introduced by the purpose-built coupler. View full abstract»

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  • Organic optoelectronics

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    Organic materials offer great potential for a wide range of applications in both linear (e.g., organic light-emitting diodes, photodetectors, polarizers, polarized light-emitting sources, birefringent optical memories) and nonlinear optics (e.g., waveguide second-harmonic generation, electro-optic modulators, directional couplers). Among the different accessible geometries, planar microcavities are interesting structures in which to study the optical properties of organic materials. Planar microcavities are one-dimensional photonic structures which result in strong modifications; of the spectral and spatial distribution of photon fields, which in turn give rise to major changes in light-matter interactions. The strong coupling between excitons and photons is one of the manifestations of such modifications and results in the formation of coupled-mode states, two-dimensional exciton polaritons. Organic molecular compounds are very attractive materials for opto-electronics applications. View full abstract»

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  • Optical filters using bends of optical waveguides

    Page(s): 155 - 157 vol.2
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    The results of calculations prove the presence of transmission characteristics dependence of optical waveguide bends on wavelength. This fact can successfully be used for creation of optical filters by choice of glass structure, radius and number of bends. The search and synthesis of new glass structures is of interest for this purpose. View full abstract»

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  • "The 2nd order of magnitude" - the video revolution and all-optical services

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    Summary form only given. "The 1st order of magnitude" - from POTS to DSL (64 kb/s to 512 kb/s) - is today being installed with a speed that exceeds expectations. It is now time to look ahead to "the 2nd order of magnitude" in research and development. This means the step from sub-Mb/s to multi-Mb/s to the end-user, and the corresponding networks. Practically the only driver for this would be video services in some form. The paper reviews the drivers for video services from a basic human and historic perspective. It also examines the bandwidth and service requirements for this "video revolution", and the role optical networks can play. The new image devices are not "stationary targets", so that the existing common perception of "2 Mb/s per image channel" will not be satisfactory for all time. Moreover, delivery will be over a multiplicity of competing media: broadcast, cable, discs, copper, and fibre. Quality and personalisation, both very bandwidth-driving, will be a critical competitive advantage. The role of optics is fundamental, but its role as an independent service-layer is more unclear, and depends on a matching between end-user and business oriented requirements, that must have a direct, technical realisation in the optical layer if the function shall be effectively solved by "all-optical" approaches. View full abstract»

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  • Numerical modelling of amplifying Gires-Tournois microinterferometer by the method of single expression

    Page(s): 118 - 121 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB) |  | HTML iconHTML  

    A model of an amplifying semiconductor Gires-Tournois microinterferometer is correctly analysed by the method of single expression (MSE). Interferometer's spectral characteristics versus the distance between the mirror and the active transient layer are obtained for different values of the active layer thickness. The optimal values of the active layer thickness and the distance between the mirror and the active layer for light maximal amplification are defined. Distributions of electric field and power flow density along the structure are obtained at the characteristic points of the structure's spectra. View full abstract»

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  • Wavelength converter-reshaper operating at 10 Gbit/s in dispersion shifted fibre

    Page(s): 193 - 195 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (317 KB) |  | HTML iconHTML  

    We demonstrate experimentally a wavelength converter-reshaper, operating at 10 Gbit/s, in a dispersion shifted optical fibre; due to the Kerr nonlinearity, it is able to generate a large number of signal replicas that permit the ITU-grid to be covered. We performed transmission experiments on the converted signals, by using an installed cable encompassing G.652, G.653 and G.655 fibres, and also polarization insensitive conversion by using a counterpropagating loop configuration. View full abstract»

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  • White-light spectral interferometry used to measure dispersion characteristics of optical fibers

    Page(s): 106 - 109 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    A new spectral-domain white-light interferometric technique employing a low-resolution spectrometer is used to measure dispersion characteristics of two-mode optical fibers. The technique utilizes the fact that the spectral interference fringes are resolved at the output of a tandem configuration of the compensated (non-dispersive) Michelson interferometer and a two-mode optical fiber only in the vicinities of so-called equalization wavelengths at which the optical path difference (OPD) in the interferometer is the same as the intermodal group OPDs. The white-light spectral interferometric technique is used to measure the spectral dependences of both the differences between propagation constants of modes and the intermodal group OPD for elliptical-core (highly birefringent) optical fibers. The measured dispersion characteristics of the optical fibers are compared with those corresponding to the results of an adequate theoretical analysis using the known parameters of the optical fibers. View full abstract»

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  • Broadband optical wavelength converters

    Page(s): 171 - 174 vol.2
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    In this letter some of the techniques nowadays used for all-optical wavelength conversion will be briefly characterized. Following, the Broadband orthogonal pumps method will be addressed in its theoretical aspects. Several evolution stages of a possible implementation will be presented as well as a new simplified version of this converting scheme. Also, some performance results will be shown. View full abstract»

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  • Plastic electronics

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    Summary form only given. Plastic electronics is a rapidly growing activity owing to the big economic impact expected from the new generation of organic electroluminescent screens. We have specialized in Angers into some aspects of the technology, which promises great technological development although still demanding fundamental and technological research: plastic solar cells, organic lasers, field effect transistors. The analysis of the problem requires in each situation a multiscale approach. I will illustrate in detail this multiscale approach in the case of plastic solar cells in which each basic process appears to be associated with a particular scale which is almost the range of the interaction: absorption, exciton diffusion, charge transfer, charge transport, electric properties. This approach permits to define the limits of the process and also the direction in which we can expect improvement of the devices. Our today's devices reach 1% solar power efficiency in bilayer structures, 2% efficiency with co-deposited molecules and 3% efficiency with polymer blends. View full abstract»

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  • Optical local area networks using uncooled photonic components

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    Summary form only given. The paper describes recent advances in optical local area network design, enabled by the development of low cost WDM based components. The network uses separate spectral channels for wavelength control and data transmission. It primarily uses multiwavelength transmission to enable flexible network control, but additional flexibility is provided through space switching. The paper describes new multiplexing and space switching components that have allowed successful network operation. View full abstract»

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  • Performance analysis of the simple prioritized buffering algorithm in optical packet switch for DiffServ assured forwarding

    Page(s): 148 - 151 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (487 KB) |  | HTML iconHTML  

    The paper addresses the problem of providing QoS management for an optical packet switch. In particular, we propose the simple prioritized buffering algorithm (SPBA) for prioritized buffer management, which aims to guarantee different packet loss probabilities to different packet streams. In contrast to other solutions, SPBA does not need any resource reservation or threshold dropping, but only makes use of priority scheduling. A theoretical model of SPBA with K classes of service applied to an optical packet switch with fiber-delay line buffers and tunable wavelength converters is presented. The analytical model is verified by simulations. View full abstract»

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  • Transmission spectra of superimposed fiber Bragg gratings

    Page(s): 122 - 124 vol.2
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    Multi-wavelength in-fiber passband optical filters have numerous applications in fiber-optic communication. In this paper, we investigate superimposed Fiber Bragg Gratings (FBG) through computer modeling. We show that by superimposing several gratings on the same length of fiber, it is possible to obtain transmission spectra with multiple passband characteristics. Investigations were carried out by using non-traditional Method of Single Expression (MSE), which accurately describes the wave propagation in the stratified media by numerically solving the wave equation. View full abstract»

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  • Strategies for spectrally efficient optical fiber communication systems with direct detection

    Page(s): 58 - 63 vol.2
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    In order to use the available optical bandwidth efficiently, efforts are under way to achieve spectral efficiencies of at least 0.8 bits/s/Hz. For such spectrally efficient systems (considering copolarized WDM-channels), we discuss the importance of filtering for different modulation formats, different channel bitrates from 10-160 Gbit/s and different dispersion map designs. It turns out that the optimisation strategy for spectrally efficient WDM systems shows considerable differences to that of single channel systems. The specific modulation format and the chosen channel bitrate turn out to be of minor importance, thus enabling simple analytic expressions for the achievable system performance. View full abstract»

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  • COST Action 273 at the National Institute of Telecommunications

    Page(s): 137 - 140 vol.2
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    The COST Action 273, "Towards Mobile Broadband Multimedia Networks", is a framework of research efforts at the European level in the mobile broadband area. The paper overviews topics in the framework of the action proposed for investigation in joint research at the National Institute of Telecommunications in Warsaw and the University of Modena and Reggio Emilia. View full abstract»

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