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Showing papers on "Optical communication published in 2003"


Journal ArticleDOI
TL;DR: An easy wiring system for optical communication using the existing power-line is proposed, which is emitted as visible-light from LED lighting according to the transmitted signal waveform without demodulating the signal from the power- line.
Abstract: White LED offers advantageous properties such as high brightness, reliability, lower power consumption and long lifetime. Indoor optical wireless communication systems employing white LED lighting have been proposed. This system will enable high quality of service by the high radiation power from this lighting equipment. And, this system does not cause or suffer from radio or electromagnetic interference. But, it is difficult for existing offices and households to install the communication cable to the ceiling. In this paper, an easy wiring system for optical communication using the existing power-line is proposed. This system is emitted as visible-light from LED lighting according to the transmitted signal waveform without demodulating the signal from the power-line. This system is expected to be applicable from the existing illuminant easily like exchanging electric bulbs. This integrated system will surely have a big impact as a new signal transmission system and its economical effect will be great. The basic performance of this system is analyzed. The actual system is built and its feasibility is shown through experiments.

361 citations


Journal ArticleDOI
TL;DR: A bit-error probability (BEP) model is developed that takes into account both building sway and turbulence-induced log amplitude fluctuations and assumes that the receiver has knowledge about the marginal statistics of the signal fading and the instantaneous signal-fading state.
Abstract: Urban optical wireless communication (UOWC) systems are considered a last-mile technology. UOWC systems use the atmosphere as a propagation medium. To provide a line of sight the transceivers are placed on high-rise building. However, dynamic wind loads, thermal expansion, and weak earthquakes cause buildings to sway. These sways distort the alignment between transmitter and receiver, causing pointing errors, the outcome of which is fading of the received signal. Furthermore, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, resulting in impaired link performance. A bit-error probability (BEP) model is developed that takes into account both building sway and turbulence-induced log amplitude fluctuations (i.e., fading of signal intensity) in the regime in which the receiver aperture, D0, is smaller than the turbulence coherence diameter, d0. It is assumed that the receiver has knowledge about the marginal statistics of the signal fading and the instantaneous signal-fading state.

304 citations


Proceedings Article
06 Jun 2003
TL;DR: In this paper, the four-sideband model of parametric amplifiers driven by two pump waves is reviewed and used to describe the conditions required to produce broad-bandwidth gain.
Abstract: Parametric amplifiers (PAs) are well-suited for optical communication systems. Not only can PAs provide high gain for arbitrary signal wavelengths, they can also conjugate the signals and convert their wavelengths. The four-sideband model of parametric amplifiers driven by two pump waves will be reviewed and used to describe the conditions required to produce broad-bandwidth gain. The flexibility of the two-pump architecture allows it to produce gain that is nearly independent of the signal polarization, and idlers whose spectral widths are comparable to that of the signal.

218 citations


Journal ArticleDOI
TL;DR: This paper derives a mathematical model to minimize transmitter power and optimize transmitter gain (divergence angle) as a function of the building-sway statistics, the communication system parameters, and the required bit-error probability (BEP).
Abstract: Urban optical wireless communication systems are considered a "last mile" technology. An optical wireless communication system uses the atmosphere as a propagation medium. In order to provide line-of-sight (LOS), the transceivers are placed on high-rise buildings. However, dynamic wind loads, thermal expansion, and weak earthquakes cause buildings to sway. These sways require the designer to increase the transmitter beam divergence angle so as to maintain LOS between the transmitter and the receiver. It is clear that an overly wide divergence angle increases the required laser power, and, as a result, terminal cost and complexity increase. On the other hand, an overly narrow beam divergence angle may result in cutoff in communication when there is building sway. In this paper, we derive a mathematical model to minimize transmitter power and optimize transmitter gain (divergence angle) as a function of the building-sway statistics, the communication system parameters, and the required bit-error probability (BEP). Reduction in laser power could improve overall system performances and cost. For example, for BEP of 10/sup -9/, we can attain at least a 4-dB reduction of the required transmitter power in comparison to a system with both half and twice the optimum beam divergence angle.

181 citations


Journal ArticleDOI
TL;DR: In this article, a sub-millimeter-sized quad corner-cube retroreflectors (CCRs) were fabricated for free-space optical communication and demonstrated a 180m free space optical communication link using a CCR as a passive optical transmitter.
Abstract: We have fabricated sub-millimeter-sized quad corner-cube retroreflectors (CCRs) for free-space optical communication. Each quad CCR structure comprises three mirrors micromachined from silicon-on-insulator wafers, and is designed to facilitate manual assembly with accurate angular alignment. Assembled CCRs exhibit mirror nonflatness less than 50 nm, mirror roughness less than 2 nm, and mirror misalignment less than 1 mrad, leading to near-ideal optical performance. The quad CCR incorporates a gap-closing actuator to deflect a base mirror common to the four CCRs, allowing their reflectivity to be modulated up to 7 kb/s by a drive voltage less than 5 V. We have demonstrated a 180-m free-space optical communication link using a CCR as a passive optical transmitter. Quad CCRs have been integrated into miniature, autonomous nodes that constitute a distributed wireless sensor network. We present an analysis of the signal-to-noise ratio of CCR-based links, considering the impact of CCR dimensions, ambient light noise, and other factors.

161 citations


Patent
02 Dec 2003
TL;DR: In this article, a plurality of radiation generating sources, such as LED dies, and a corresponding plurality of optical waveguides are also provided, with each waveguide having a first and a second end, each first end being in optical communication with the corresponding LED die.
Abstract: An illumination system includes a plurality of radiation generating sources, such as LED dies. A corresponding plurality of optical waveguides is also provided, with each waveguide having a first and a second end, with each first end being in optical communication with the corresponding LED die. An array of corresponding passive optical elements is interposed between the plurality of LED dies and the corresponding first ends of the plurality of optical waveguides. The illumination system provides for substantially high light coupling efficiency and an incoherent light output that can appear to the human observer as arising from a single point of light. In addition, the light can be output remotely at one or more locations and in one or more directions.

160 citations


Book
07 Nov 2003
TL;DR: In this paper, the above threshold analysis and optimization of DFB laser Diodes using the Transfer Matrix Method is presented. But this method is not suitable for the above-threshold analysis of DFTD structures.
Abstract: Preface.Acknowledgements.Glossary of Abbreviations.Glossary of Symbols.1. An Introduction to Optical Communication Systems.2. Principles of Distributed Feedback Semiconductor Laser Diodes: Coupled Wave Theory.3. Structural Impacts on the Solutions of Coupled Wave Equations: An Overview.4. Transfer Matrix Modelling in DFB Semiconductor Lasers.5. Threshold Analysis and Optimization of Various DFB LDs Using the Transfer Matrix Method.6. Above-Threshold Characteristics of DFB Laser Diodes: A TMM Approach.7. Above-Threshold Analysis of Various DFB Lase r Structures Using the TMM.8. Circuit and Transmission-Line Laser Modelling (TLLM) Techniques.9. Analysis of DFB Laser Diode Characteristics Based on the Transmission-Line Modelling (TLLM).10. Wavelength Tunable Optical Filters Based on DFB Laser Structures.11. Other Wavelenght Tunable Optical Filters Based on the DFB Laser Structure.12. Conclusion, Summary and Suggestions.Index.

145 citations


Journal ArticleDOI
TL;DR: In this paper, an optical carrier supply module (OCSM) was proposed for superdense wavelength division multiplexing (SD-WDM) networks that utilize a large number of wavelengths with narrow channel spacing.
Abstract: This paper presents an optical carrier supply module (OCSM) that functions as a common multicarrier light source, a wavelength bank, for superdense wavelength-division multiplexing (SD-WDM) networks that utilize a large number of wavelengths with narrow channel spacing. A novel sideband generator based on a sinusoidal amplitude-phase hybrid modulation scheme is the key technique. The sideband generator generates nine flattened optical sidebands within 3 dB from one seed light source, and the input from wavelength-division multiplexing (WDM) seed carriers expands the number of generated sidebands. Scalability against the number of wavelengths is achieved by increasing the number of seed carriers used. The SD-WDM system employing OCSM reduces the number of laser diodes (LDs) and attendant wavelength monitoring/stabilization circuits. Multiple distributions to SD-WDM networks by splitting the OCSM output can promote this effect. We designed OCSM and experimentally investigated its performance pertaining to the electrical signal-to-noise ratio (SNR) of the OCSM output. The experimental results show the wavelength scalability to 1000 channels. We also developed an OCSM prototype that generated 12.5-GHz-spaced 256-channel WDM carriers. All the generated carriers exhibit the electrical SNR of more than 31.5 dB at 2.5 Gb/s and the power flatness of within 3 dB. The distribution over 100 SD-WDM networks is experimentally confirmed.

138 citations


Patent
23 Sep 2003
TL;DR: In this article, an optical interconnection module (60) having an enclosure defining walls and a cavity within the walls for receiving and supporting optical fibers (21-32) and connectors (40); an optical connector station (51-56) formed in a wall of the module having a plurality of optical fiber connectors; the optical paths and the optical connectors being optically interconnected by optical fibers disposed in the cavity.
Abstract: An optical interconnection module (60) having: an enclosure defining walls and a cavity within the walls for receiving and supporting optical fibers (21-32) and connectors (40); an optical interconnection section formed in a wall of the module, the optical interconnection section having a multi-fiber connector (40) with multiple optical paths formed therein, the optical paths being arranged in a generally planar array with the paths being immediately adjacent to at least one other optical path for optical alignment with optical fibers in an optical fiber ribbon (20); an optical connector station (51-56) formed in a wall of the module having a plurality of optical fiber connectors; the optical paths and the optical connectors being optically interconnected by optical fibers disposed in the cavity, fiber pairs being formed by the optical fibers, at least one of the fiber pairs being routed to a respective connector station that is in optical communication with the optical paths.

132 citations


Journal ArticleDOI
TL;DR: In this paper, an advanced microelectromechanical systems (MEMS) optical switch that consists of actuator, suspension beam, micromirror, and fiber grooves using deep RIE (DRIE) etching fabrication process is described.
Abstract: Optical switch is widely used in the optical fibre communication networks. This paper described an advanced microelectromechanical systems (MEMS) optical switch that consists of actuator, suspension beam, micromirror, and fiber grooves using deep RIE (DRIE) etching fabrication process. Based on the specification and design requirements of optical switch, the DRIE etching fabrication process is combined with the anisotropic and isotropic, the two different types of etching methods that improve the surface roughness of the micro mirror. Net structure with arcs is introduced to obtain a good release and microloading effect is used and prevented trickily. As a result, promising performances of the optical switch such as low driving voltage of 30 V, low insertion loss, fast switching speed of less than 100 μs and high reliable operation of more than 20 million cycles are achieved. The actuator of the optical switch enables to the delivery of a moving displacement which is as large as 45 μm. This MEMS optical switch has a broad applications for fibre optical communication systems such as n×n optical crossconnects (OXCs), variable optical attenuator (VOA), etc.

118 citations


Journal ArticleDOI
TL;DR: The basic principles and characteristics of MSM techniques in optical wireless communications are presented and some block codes that convert information bits to be transmitted to the symbol amplitudes of subcarriers are used to increase the minimum value of the MS electrical waveform.
Abstract: This article overviews multiple-subcarrier modulation techniques in optical wireless communications. The basic principles and characteristics of MSM techniques in optical wireless communications are presented. MSM optical wireless systems are explained where some block codes that convert information bits to be transmitted to the symbol amplitudes of subcarriers are used to increase the minimum value of the MS electrical waveform. MSM optical communications systems using subcarrier signal point sequences (SSPS) that can improve the power efficiency of MSM systems are also explained. The performance of MSM optical communications systems is presented in the intensity modulation with direct detection (IM/DD) channel without dispersion and in atmospheric optical communications where the effects of scintillation exist.

Journal ArticleDOI
TL;DR: In this article, the performance of ultra-fast all-optical XOR gate using two types semiconductor optical amplifier-based Mach-Zehnder interferometers (SOA-MZIs) is analyzed.

Journal ArticleDOI
TL;DR: In this paper, an optical frequency comb generator, an optical injection-locking filter, and a unitraveling-carrier photodiode were used to synthesize 10-110 GHz millimeter-wave signals with 3dBm output at 60 GHz.
Abstract: This paper demonstrates multi-octave, milliwatt-class millimeter-wave synthesis using three key components: an optical frequency comb generator, an optical injection-locking filter, and a unitraveling-carrier photodiode. The experimental system synthesizes 10-110-GHz millimeter-wave signals with 3-dBm output at 60 GHz. Phase noise results are also presented.

Journal ArticleDOI
TL;DR: A model of light transmission through fogs of different optical densities and types using Monte Carlo simulations is developed and the handicap of a transceiver pointing error is added to the model, and the paradoxically advantageous aspects of the transmission medium are exposed.
Abstract: Terrestrial optical wireless communication (OWC) is emerging as a promising technology, which makes connectivity possible between high-rise buildings and metropolitan and intercity communication infrastructures. A light beam carries the information, which facilitates extremely high data rates. However, strict alignment between the transmitter and the receiver must be maintained at all times, and a pointing error can result in a total severance of the communication link. In addition, the presence of fog and haze in the propagation channel hampers OWC as the small water droplets scatter the propagating light. This causes attenuation due to the resultant spatial, angular, and temporal spread of the light signal. Furthermore, the ensuing low visibility may impede the operation of the tracking and pointing system so that pointing errors occur. We develop a model of light transmission through fogs of different optical densities and types using Monte Carlo simulations. Based on this model, the performance of OWC in fogs is evaluated at different wavelengths. The handicap of a transceiver pointing error is added to the model, and the paradoxically advantageous aspects of the transmission medium are exposed. The concept of a variable field of view receiver for narrow-beam OWC is studied, and the possibility of thus enhancing communication system performance through fog in an inexpensive and simple way is indicated.

Journal ArticleDOI
TL;DR: Using the new approach, conventional passive optical components such as arrayed waveguide gratings for wavelength-division-multiplexed transmission systems can be fabricated in a more compact way than using standard silica-on-silicon waveguide methods.
Abstract: The rapidly growing optical communication market requires photonic components with ever-increasing functionality and complexity that can be fabricated reliably at low cost. Of the various approaches used to fabricate photonic components, those based on planar waveguides have achieved high performance and represent a promising path toward compact integration of optical functions. We present an overview of an approach used to produce an optical single-mode waveguide. Through its strong mode confinement, the approach makes it possible to integrate optical filter functions with higher functionality, as required for high-data-rate communication networks. The waveguide is based on the use of a silicon oxynitride (SiON) core and silicon oxide cladding layers, and can be fabricated using conventional chip fabrication techniques. Using the new approach, conventional passive optical components such as arrayed waveguide gratings for wavelength-division-multiplexed transmission systems can be fabricated in a more compact way than using standard silica-on-silicon waveguide methods. Moreover, the realization of more enhanced, adaptive optical functions such as finite- impulse-response as well as infinite-impulse-response filters is possible. Reconfiguration is achieved through the thermo-optic effect. A reconfigurable gain-flattening filter and an adaptive dispersion compensator are presented as examples.

Proceedings ArticleDOI
24 Jun 2003
TL;DR: The solution, called light-trails, coalesces a hardware platform and software protocol for realizing efficient optical communications from IP bursts to lightpaths and presents the first practically implementable solution to enable burst transport with mature and off-the-shelf technology and eased switching requirements.
Abstract: We propose a solution for implementing a conceptual framework for catering to dynamic traffic in the optical domain. The solution, called light-trails, coalesces a hardware platform and software protocol for realizing efficient optical communications from IP bursts to lightpaths. It is a paradigm shift from conventional optical communication modes, in supporting, amongst others, very fast lightpath setup and tear down - burst communication - and presenting a novel approach to bandwidth management and provisioning for dynamically configurable networks and a first solution to support multicasting, a key element for many of the central motivator services for optical capacity needs. Contrary to existing proposals for IP type communication, bursts etc., it also presents the first practically implementable solution to enable burst transport with mature and off-the-shelf technology and eased switching requirements.

Journal ArticleDOI
TL;DR: In this paper, singlemode ridged optical waveguide devices using GaN/AlGaN heterostructures have been designed, fabricated, and characterized for operation in 1550 nm wavelength window.
Abstract: Refractive indices of AlxGa1−xN with different Al concentrations have been measured in infrared wavelength regions. Single-mode ridged optical waveguide devices using GaN/AlGaN heterostructures have been designed, fabricated, and characterized for operation in 1550 nm wavelength window. The feasibility of developing photonic integrated circuits based on III-nitride wide-band-gap semiconductors for fiber-optical communications has been discussed.

Patent
11 Jul 2003
TL;DR: In this paper, an optical communication system by which an optical axis is easily adjusted between a transmitting part and a receiving part was proposed. But the optical axis was not adjusted between the transmitting and receiving parts.
Abstract: PROBLEM TO BE SOLVED: To provide an optical communication system by which an optical axis is easily adjusted between a transmitting part and a receiving part. SOLUTION: The transmitting part 12 is mounted on an equipment main body 11 and transmits an optical signal with an elliptic light distribution pattern which is long in the vertical direction and short in the horizontal direction. The transmitting part 12 faces to the receiving part 13 and the optical signal transmitted from the transmitting part 12 is received by the receiving part 13. COPYRIGHT: (C)2003,JPO

Proceedings ArticleDOI
08 Jun 2003
TL;DR: A MEMS mirror for optical switching consisting of a double-gimbaled mirror with on-chip high voltage drive electronics and low-voltage CMOS for capacitive position sense is reported on.
Abstract: The ability of silicon micromachining to produce small, precision, movable parts provides an opportunity for MEMS component use in optical communications networks. To address this potential market, Analog Devices has developed the Optical iMEMS/sup /spl reg// process for fabricating MEMS optical components with integrated, on-chip electronics. While this process could be used to make a variety of optics components including mirrors, shutters and actuators for precision alignment, we report here on a MEMS mirror for optical switching. The device consists of a double-gimbaled mirror with on-chip high voltage drive electronics and low-voltage CMOS for capacitive position sense. The mirror can tilt about both the X- and Y-axis, with position sense in both directions of tilt.

Patent
Gary Sasser1, Chris Togami1
17 Nov 2003
TL;DR: In this paper, an integrated array for optoelectronic components in an optical communications system is disclosed, which consists of a plurality of optolectronic modules such as optical transceivers, in a compact, integrated geometry for positioning within an optical device, such as an optical switch or router.
Abstract: An integrated array for optoelectronic components in an optical communications system is disclosed. The integrated array incorporates a plurality of optoelectronic modules, such as optical transceivers, in a compact, integrated geometry for positioning within an optical device, such as an optical switch or router. In one embodiment, the integrated array includes a component structure comprised of a plurality of optical transceiver sub-modules, each having dual optical ports. The component structure is integrated as a single structure to minimize the spacing between each transceiver sub-module. This in turn increases the optical port density of the integrated array. The integrated array is received by a cage that is attached to a host board within the optical device. A latching mechanism is included to selectively secure the integrated array within the cage.

Patent
18 Aug 2003
TL;DR: In this article, an AC power source light modulation apparatus is used for broadcasting useful data from a computer system to one or more specialized optical detectors located within any given space illuminated by standard electrical light fixtures all connected downstream from this same power source.
Abstract: An AC power source light modulation apparatus is used for broadcasting useful data from a computer system to one or more specialized optical detectors located within any given space illuminated by standard electrical light fixtures all connected downstream from this same power source. The AC power modulation impressed by this system on the power signal, causes imperceptible changes to the light output of electrical lamps being supplied electricity from this common AC power source. This invention may be installed at any AC power source located upstream of one or more standard light fixtures in order to induce changes that may include deltas in amplitude and phase in the luminous output of these light fixtures. Changes in the electrical ambient illumination are produced by this modulated power signal which result in the broadcasting of optical signals that are received, demodulated and decoded by a specialized type of optical data receiver. This optical data broadcasting network includes a new type of optical networking card or optical receiver, capable of demodulation and decoding changes in the characteristics of the light output of the electrical lamps, which are generally imperceptible to the human eye. The AC power source light modulation apparatus and the optical receiver units comprise an optical data broadcasting network that provides a low-cost and single-point installation for applications where the lowest cost and the simplest indoor wireless infrastructure is desirable by users. Including applications such as the automation of prices in retail and supermarkets and for use by other applications that require optical communications for data broadcasting and remote wireless networking systems.

Patent
03 Mar 2003
TL;DR: In this paper, a light source apparatus for radiating an induced emission light from a semiconductor laser device (200) to a free space via a multiple scattering optical system was proposed.
Abstract: A light source apparatus for radiating an induced emission light from a semiconductor laser device (200) to a free space via a multiple scattering optical system. The multiple scattering optical system comprises a first region (204) close to the semiconductor laser device (200) and a second region (205), which is in contact with the first region (204) and leads to the free space. A scattered substance is contained at a high concentration in the first region (204), the second region (205) has a lens section (205a) as a magnifier for at least the principal part of a secondary face light source formed over the boundary face between the first and second regions (204, 205). Thus, a simple constitution provides a low-power consumption light source apparatus small is size, low in cost, and suitable for an optical communication system having a high-speed, wide-range communication area, and an optical communication module comprising this apparatus. This apparatus enables a high efficiency of extracting light safe to human eyes even with a high-output semiconductor light-emitting device.

Patent
John Mcnicol1, Kieran Parsons1, Leo Strawczynski1, Kim B. Roberts1, Maurice O'Sullivan1 
11 Jul 2003
TL;DR: In this article, a compensation function is determined that substantially mitigates the chromatic dispersion, and the communications signal is then modulated in the electrical domain using the compensation function, which is implemented in the transmitter, using a look-up-table and digital-to-analog converter.
Abstract: Optical dispersion imposed on a communications signal conveyed through an optical communications system is compensated by modulating the communications signal in the electrical domain. A compensation function is determined that substantially mitigates the chromatic dispersion. The communications signal is then modulated in the electrical domain using the compensation function. In preferred embodiments, compensation is implemented in the transmitter, using a look-up-table and digital-to-analog converter to generate an electrical predistorted signal. The electrical predistorted signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical communications system.

Journal ArticleDOI
TL;DR: In this paper, a new concept of optical packet/burst switching suitable for generalized multiprotocol label switched (GMPLS)-based optical networks is presented, in which a wavelength label as well as an orthogonally modulated label, with respect to the payload modulation format, are used for switching in the node, whereas the orthogonal label defines the label-switched path.
Abstract: In this paper, we present a new concept of optical packet/burst switching suitable for generalized multiprotocol label switched (GMPLS)-based optical networks. In such networks, optical labeled switched paths are being established in a similar way as label-switched paths in MPLS. We use a wavelength label as well as an orthogonally modulated label, with respect to the payload modulation format, and which is encoded using either frequency-shift keying (FSK) or differential phase-shift keying (DPSK). Wavelength is used for switching in the node, whereas the orthogonal label defines the label-switched path. We present both simulation and experimental results to assess transmission performance of the proposed combined modulation scheme. In addition, we propose a suitable optical node architecture that can take advantage of this stacked label concept. Toward this, we use widely tunable wavelength converters to efficiently route IM/FSK (or IM/DPSK) optically labeled packets in an arrayed-waveguide grating (AWG)-based node structure. We present performance simulation results in terms of packet loss ratio and internal block probability. Internal blocking is an inherent problem of AWG optical routers, and a specific wavelength assignment algorithm has been developed to minimize it. Finally, the feasibility of IM/FSK transmission is experimentally demonstrated over an 88-km single-mode fiber span, and novel aspects of FSK generation and detection techniques are presented.

Book ChapterDOI
24 Feb 2003
TL;DR: Contrary to existing proposals for IP type communication in the optical domain light-trail node architecture also presents the first practically implementable solution to enable optical transport with mature technology, non stringent optical switching requirements, and presenting a much more cost effective alternative to electronics.
Abstract: We propose a solution for implementing a conceptual framework for IP centric communication in the optical domain. The solution, termed Lighttrails, is a combination of node architecture and protocol for realizing efficient optical communications from IP bursts to dynamic lightpaths. It is a paradigm shift from conventional optical communication modes, in supporting amongst others, very fast optical connection set up and tear down for burst of lightpaths communication, dynamic and highly bandwidth efficient sub-lambda provisioning. Light-trails also provide a first solution to optical multicasting, a key element for many of the emerging services that motivate the need for optical capacity. Contrary to existing proposals for IP type communication in the optical domain light-trail node architecture also presents the first practically implementable solution to enable optical transport with mature technology, non stringent optical switching requirements, and presenting a much more cost effective alternative to electronics.

Proceedings ArticleDOI
20 Oct 2003
TL;DR: A Light-trails solution that is applicable to mesh networks and presents the first practically implementable solution to enable optical transport with mature technology, nonstringent optical switching requirements, and potentially presents a cost effective alternative to electronics in supporting IP networks.
Abstract: Light-trails communication (Chlamtac and Gumaste, 2003) proposes a solution for implementing a conceptual framework for IP centric communication in the optical domain which is a combination of node architecture and protocol for realizing efficient optical communications from IP bursts to dynamic lightpaths. In this paper we introduce a Light-trails solution that is applicable to mesh networks. Contrary to existing proposals for IP type communication in the optical domain light-trail node architecture also presents the first practically implementable solution to enable optical transport with mature technology, nonstringent optical switching requirements, and potentially presents a cost effective alternative to electronics in supporting IP networks.

Journal ArticleDOI
TL;DR: In this paper, slow wave structures that consist of a cascade of directly coupled optical resonators have been proposed for all-optical processing, which could make them the cornerstone of switches and other wideband devices.
Abstract: Nonlinear processes are enhanced in slow wave structures that consist of a cascade of directly coupled optical resonators. Although slow wave propagation has not yet been deployed at optical frequencies, new research could make slow wave structures the cornerstone of switches and other wideband devices for all-optical processing.

Journal ArticleDOI
TL;DR: Electronic tracking of IR links allows both high data rates and high capacity for wireless access in small office and home environments and is shown in an experimental demonstrator.
Abstract: A high-speed wireless system (/spl ges/100 Mb/s) for indoor infrared (IR) communications via the line of sight is described and feasibility is shown in an experimental demonstrator. A diffuse link is used for connectivity, and tracked directed links are used for high-speed communications. The transmitter is made of a laser diode array in combination with multiple-beam forming optics. For the receiver (Rx), a wide-angle lens, and an avalanche photodiode array are used. For the diffuse link, the signals from all pixels in the array are combined. Pixels are selectively addressed to realize directed links. Fast electronic tracking of a directed link is possible by switching the signal path onto the right pixel in the array. Diffuse link, directed link, position detection, and tracking can be realized with one and the same transceiver hardware. A favorite system design is derived from constraints due to the IR channel, eye safety, lenses, photodetectors, and the overall system complexity. The experimental system shows some key features, namely 155-Mb/s wireless transmission over a distance of nearly 2 m with electronic tracking at an imaging IR Rx. Electronic tracking of IR links, thus, allows both high data rates and high capacity for wireless access in small office and home environments.

Patent
06 Nov 2003
TL;DR: In this paper, a converging lens is arranged between the light source and the optical fiber to generate a light intensity distribution in light reflected by the light entrance face depending on a position where the light beam is incident on the entrance face.
Abstract: An optical communication device includes a light source that emits a light beam and an optical fiber having a core and a cladding. The optical fiber has a light entrance face having a core region and a cladding region. The light beam emitted by the light source is converged by a converging lens on the core region and is transmitted through the optical fiber. The entrance face is configured to generate a light intensity distribution in light reflected by the light entrance face depending on a position where the light beam is incident on the entrance face, a converging lens arranged between the light source and the optical fiber.

01 Aug 2003
TL;DR: In this paper, a design control table for an optical communications link from a spacecraft in Mars orbit to a ground-based receiving station on Earth is described, along with an end-to-end system analysis to provide the expected signal and background-noise photons as a function of the Earth-Mars range.
Abstract: This article describes the elements of a design control table for an optical communications link from a spacecraft in Mars orbit to a ground-based receiving station on Earth. A fixed average laser transmitter power of 5 W transmitted through a 30-cmdiameter near-diffraction-limited telescope is assumed, along with a 10-m-diameter ground receiving antenna. Pulse-position modulation of the laser with direct detection also is assumed. An end-to-end systems analysis is presented to provide the expected signal and background-noise photons as a function of the Earth–Mars range. The signal and noise photons received are treated using an ideal Poisson channel model in order to predict data rates when Mars is close to conjunction. The data rates range from 5 to 40 Mb/s with a large part of the uncertainty owing its origin to variability of the atmosphere. The article also concludes that further work is required in order to narrow the rather wide range of preliminary data rates presented.