Showing papers on "Wavelength-division multiplexing published in 1993"

A Wavelength-Convertible Optical Network

Abstract: Wavelength-division multiplexing is emerging as the dominant technology in future all-optical network. To efficiently use the wavelengths, wavelength converters are employed for a circuit-switched optical network in which a circuit can change its wavelength to resolve wavelength conflicts and to reuse the wavelengths. To improve the efficiency, a few converters are provided and shared by the incoming circuits in the share-per-node or the share-per-link wavelength-convertible switch. A heuristic algorithm for dynamic routing is used to reduce the number of converters. Performance gain in call blocking probability and fairness and in the reduction of the number of converters are shown

Spectrum-sliced fiber amplifier light source for multichannel WDM applications

Abstract: A potentially inexpensive light source for multichannel WDM applications is proposed The high-power amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA), which is already in the single-mode fiber, can be efficiently divided into many channels by using an integrated optic wavelength-division-multiplexing (WDM) demultiplexer This spectrum-sliced ASE can be used as light sources for WDM systems in place of several wavelength-selected DFB lasers To demonstrate the principle, the 40-nm-wide ASE spectrum of an EDFA was sliced using a narrow optical filter (3-dB bandwidth: 13 nm), and the resulting source was used for the transmission of up to 17 Gb/s of data The problem of spontaneous-spontaneous beat noise in these sources is dealt with It is estimated that the total capacity would be about 40 Gb/s, realistically, since the channel spacing should be at least three times the optical bandwidth of each channel to avoid crosstalk >

Simple multiplexing scheme for a fiber-optic grating sensor network.

Abstract: A new approach for the interrogation of a large number of fiber-optic grating sensors is proposed and demonstrated for a small number of sensors in which signal recovery is achieved by matching a receiving grating to its corresponding sensor. This technique is demonstrated for both quasi-static and periodic measurands, and the resolution achieved for a single sensor–receiving grating pair for quasi-static strain is 4.12 μ∊.

Demonstration, using sliding-frequency guiding filters, of error-free soliton transmission over more than 20 Mm at 10 Gbit/s, single channel, and over more than 13 Mm at 20 Gbit/s in a two-channel WDM

Abstract: By transmitting trains of 2 14 bit pseudorandom words in a recirculating loop containing strong, sliding-frequency guiding filters, «error-free» (measured BER≤10 -9 ) soliton transmission at 10 Gbit/s, single channel, and at 20 Gbit/s in a two channel WDM is demonstrated, over paths as great as 20 000 km and 13 000 km, respectively

More than 100-wavelength-channel picosecond optical pulse generation from single laser source using supercontinuum in optical fibres

Abstract: A novel method for generating multiwavelength-channel picosecond optical pulses from a single laser source is proposed using supercontinuum in optical fibres combined with an all-fibre birefringent periodic filter. More than 100-wavelength-channel, 10 ps optical pulses are generated simultaneously over a 1.224–1.394 μm spectral range with a 1.9 nm spacing using a 7.6 ps Nd : YLF laser pulse source.

Wavelength division multiplexed optical communication transmitters

Abstract: A wavelength-division-multiplexed transmitter has a single modulator modulating the output of an array of individually actuable semiconductor lasers integrated onto the same substrate as the modulator. An optical combiner integrated onto the same substrate between each of the lasers and the single modulator combines the outputs of the lasers. One or more of the lasers are activated as desired for wavelength division multiplexing.

Multiwavelength survivable ring network architectures

Abstract: A new architecture for implementing unidirectional and bidirectional self-healing interoffice ring networks using wavelength division multiplexing (WDM) technology for growth is proposed. The working ring uses all-optical drop-and-add multiplexers at each office and the protection path uses optical amplifiers and optical switches. The use of WDM technology, combined with all-optical drop-and-add multiplexers, accommodates growth to a network capacity of more than 1 Tb/s. >

Optical Fiber Amplifiers: Design and System Applications

Abstract: Manufacturing of active fibers properties of rare-earth ions in glass host materials characterization measurements for rare-earth-doped fibers basics of 1550-nm fiber amplifiers optimization of er-doped fiber pump wavelength choice for 1550-nm amplifiers improved 1550-nm amplifiers in advanced configurations the 1300-nm amplifiers in advanced configurations the 1300-nm fiber amplifier fiber amplifiers in digital direct detection systems distributed fiber amplifiers amplifiers for AM-modulated systems

A 16*1 wavelength division multiplexer with integrated distributed Bragg reflector lasers and electroabsorption modulators

Abstract: The integrated operation of a 16*1 wavelength-division-multiplexed (WDM) source with distributed Bragg reflector (DBR) lasers and electroabsorption modulators has been demonstrated. By using repeated holographic exposures and wet chemical etching, 16 different wavelengths from 1.544 to 1.553 mu m with an average channel spacing of 6 AA are obtained. A high-performance combiner is used to obtain a very uniform coupling into the single-output waveguide, and with the integration of an optical amplifier an average optical power of -8 dBm per channel is coupled into a single-mode fiber. >

20-nm optical wavelength conversion using nondegenerate four-wave mixing

Abstract: Wavelength conversion of optical signals over 20 nm is demonstrated using highly nondegenerate four-wave mixing in a semiconductor traveling-wave optical amplifier. This technique has the potential for extremely-high-speed operation and allows continuous tuning of both input and output wavelengths over the amplifier gain bandwidth. It is demonstrated that, even for such a large wavelength conversion range, it is possible to obtain conversion efficiencies in excess of -10 dB and high extinction ratios. The feasibility of the technique is demonstrated by system measurements at 622 Mb/s, showing a 1.1-dB power penalty at 10/sup -9/ bit error rate (BER). >

Arrayed-waveguide grating add-drop multiplexer with loop-back optical paths

Abstract: A novel configuration for a multiplexer which can drop and add desired wavelength channels while transmitting other channels is proposed based on an arrayed-waveguide grating geometry with loopback optical fibre paths. A 15channel multiplexing function with a 0.8nm wavelength spacing is experimentally confirmed by using silica-based planar lightwave circuit technology.

The impact of optical amplifiers on long-distance lightwave telecommunications

Abstract: The potential of erbium-doped fiber amplifiers (EDFA) and wavelength-division multiplexing (WDM) technology for expanding transmission capacity in long-distance telecommunications is examined. Properties of EDFA are nearly ideal for application in lightwave long-haul transmission. Nonlinear effects in the transmission fiber and amplifier spontaneous emission noise limit the performance and therefore dictate the design of long-distance amplified systems, especially those employing WDM. The next-generation transoceanic system will use EDFA as repeaters, yielding a capacity almost ten times larger than what is available today. Multichannel WDM soliton transmission promises further substantial enhancement. Terrestrial long-haul networks will also benefit greatly from amplified WDM systems designed to mine the large inherent bandwidth in the embedded fiber. The ten- to fifty-fold capacity increase over present systems not only will provide for ample growth, but also will enable network operators to enhance operational flexibility and network functionality, and to facilitate a fast-recovery self-healing capability through cost-effective redundant routing. >

8*10 Gb/s transmission through 280 km of dispersion-managed fiber

Abstract: Eight WDM channels each operating at 10 Gb/s were transmitted through 280 km of dispersion-shifted fiber concatenated with small amounts of conventional fiber. No degradations from optical nonlinearities were observed. >

Protocols for optical star-coupler network using WDM: performance and complexity study

Abstract: The efficiency of protocols coordinating the data transmission between the transmitter and receivers in a network of stations connected using a passive star coupler, equipped with fixed transmitters and tunable receivers, and using wavelength-division multiplexing is discussed. Two reservation-based protocols with varying degrees of signaling complexity are proposed: the dynamic allocation scheme (DAS), which dynamically assigns slots on a packet-by-packet basis, and the hybrid time-division-multiplexing (TDM) scheme (HTDM), which combines the TDM and the DAS scheme and allows both preassigned and dynamic slot assignment. Analytical results are derived for the delay performance of the two schemes and compared with that of TDM. It is shown that the performance of DAS under ideal conditions is close to optimal, but its signaling costs are exorbitantly high. On the other hand, HTDM has lower signaling needs, but has higher delays when compared to DAS. >

All-optical packet-switched metropolitan-area network proposal

Abstract: A proposal for developing a precompetitive, commercially viable all-optical network architecture using dense optical wavelength division is described. The objective was to demonstrate a packet-switched high-capacity all-optical LAN/MAN network based on wavelength-division multiplexing (WDM) and capable of supporting several hundred to a thousand nodes, each requiring gigabit-per-second throughputs. The discussion covers the rationale and objectives of the program; tunable components, optical amplifiers, network protocol, and application development; network interconnection studies; and testbed construction. >

Tunable liquid-crystal Fabry-Perot interferometer filter for wavelength-division multiplexing communication systems

Abstract: We explain how to obtain the bandwidth and tunable range required for wavelength-division multiplexing communication systems and how to design tunable liquid-crystal Fabry-Perot interferometer filters. The main factors determining the performance are liquid-crystal loss, mirror loss, surface roughness, and parallelism, as well as mirror reflectivity and cavity gap. Experimental results closely agree with the designed performance. Temperature dependence, response time, acceptable input power, and reliability are investigated. Pigtailed polarization-independent filter modules with a Peltier controller are made and are shown to have low polarization dependence ( >

Wavelength division multiplexed fiber optic link for RF polarization diversity receiver

Abstract: A single transmission optical fiber is used to transmit RF signals of the same frequency but different polarization from a source to a polarization diversity receiver without introducing interference between the signals. The incoming signal of one polarization modulates a first laser transmitter operating at one wavelength, and the incoming signal of the other polarization modulates a second laser transmitter operating at a different, second wavelength. The two modulated optical beams are combined in an optical coupler whose output is connected to the transmission fiber leading to the polarization diversity receiver. At the receiver, a wavelength division multiplexing coupler is used to separate out the two modulated optical carriers. The two RF signals used to modulate the laser transmitters are separately recovered via photodiode detectors to provide inputs to the polarization diversity receiver.

Tapered Fabry-Perot waveguide optical demultiplexer

Abstract: We describe a novel waveguide spectrometer for use in wavelength division multiplexing (WDM) systems. A high refractive index resonator is coupled to a waveguide and extracts light from the waveguide at its resonance frequency. A taper in the thickness of the resonator allows light of different wavelengths to be extracted at different positions. A structure is fabricated for use at 750 nm with a measured dispersion of 29 nm/cm and a wavelength resolution of 1 nm. The device operation is in good agreement with first-order coupled-mode calculations. >

Wavelength-division multiplexed optical integrated circuit with vertical diffraction grating

Abstract: A semiconductor optical integrated circuit for wave division multiplexing has a semiconductor waveguide layer, a succession of diffraction grating points in the waveguide layer along a predetermined diffraction grating contour, a semiconductor diode array in the waveguide layer having plural optical ports facing the succession of diffraction grating points along a first direction, respective semiconductor diodes in the array corresponding to respective ones of a predetermined succession of wavelengths, an optical fiber having one end thereof terminated at the waveguide layer, the one end of the optical fiber facing the succession of diffraction grating points along a second direction, wherein the diffraction grating points are spatially distributed along the predetermined contour in such a manner that the succession of diffraction grating points diffracts light of respective ones of the succession of wavelengths between the one end of the optical fiber and corresponding ones of the optical ports.

The receiver collision avoidance (RCA) protocol for a single-hop WDM lightwave network

Abstract: We propose a multiple access protocol for a single-hop wavelength division multiplexing (WDM)-based multichannel local lightwave network. The protocol can support a large number of high-speed bursty traffic nodes interconnected via a passive optical star coupler. Each node is equipped with only one transmitter and one receiver, both of which are tunable over all the channels. A single control channel is established to arbitrate access to the other channels, called data channels. Access to the control channel is provided via a variation of slotted ALOHA so that the system is scalable. Unlike other protocols proposed in [11], [18], [23], our protocol contains a simple mechanism which can dynamically detect and avoid receiver collisions (hence it is called the receiver collision avoidance (RCA) protocol)

Hierarchical scalable photonic architectures for high-performance processor interconnection

Abstract: Introduces two hierarchical optical structures for processor interconnection and compares their performance through analytic models and discrete-event simulation. Both architectures are based on wavelength division multiplexing (WDM) which enables multiple multi-access channels to be realized on a single optical fiber. The objective of the hierarchical architectures is to achieve scalability yet avoid the requirement of multiple wavelength tunable devices per node. Furthermore, both hierarchical architectures are single-hop: a packet remains in the optical form from source to destination and does not require cross dimensional intermediate routing. >

Topologies for wavelength-routing all-optical networks

Abstract: Three regular meshed topologies are compared in light of their possible use for the implementation of large all-optical wavelength-routing communication networks (or interconnection systems). These systems provide all source-destination pairs with end-to-end transparent channels that are identified through a wavelength and a physical path. The considered topologies are the K-dimensional bidirectional square lattice, the twin shuffle, and the de Bruijn graph. The comparison is based on the maximum and average distance between source and destination (number of traversed nodes), on the degree of connectivity for each node (number of input and output fibers), and on the minimum number of wavelengths in the WDM comb necessary to discriminate all source-destination pairs. >

Wavelength conversions ∼1.5 μm by difference frequency generation in periodically domain‐inverted LiNbO3 channel waveguides

Abstract: Wavelength conversions ∼1.5 μm are realized by difference frequency generation in periodically domain‐inverted LiNbO3 channel waveguides for the first time. A wide wavelength conversion bandwidth, which is very important for future wavelength division multiplexing optical communication system, is demonstrated in this kind of devices.

Optical fiber solitons, their properties and uses

Abstract: The history and mathematical formulation of solutions are briefly reviewed. Solitons of the nonlinear Schrodinger equation are studied in greater detail because they describe nonlinear pulse propagation on dispersive optical fibers. The proposal by A. Hasegawa and the experiments of L.F. Mollenauer on long distance soliton propagation for use in repeaterless transoceanic fiber transmission cables are described. In 1986, limitations on the distance that can be spanned by a repeaterless link for a given bit rate were shown to exist. It has been shown recently that by proper design these limitations can be overcome, so that newer transoceanic cable designs are likely to utilize solitons. The special properties of solitons make them particularly suited for all optical switching and logic operations. Some recent experiments with such switches are described. >

A prototype circuit-switched multi-wavelength optical metropolitan-area network

Abstract: A description is given of Rainbow, a prototype optical network based on wavelength-division multiaccess (WDMA). Rainbow supports full-duplex circuit-switched interconnection of up to 32 workstations over a diameter of 25 km, at sustained bit rates of up to 300 Mb/s per connection, allowing a total network capacity of 9.6 Gb/s. Different connections are transparent to each other and may use different protocols and bit rates. >

Optical path layer technologies to enhance B-ISDN performance

Abstract: Path layer technologies play a key role in the development of a powerful and failure resilient broadband integrated services digital network (B-ISDN). The authors discuss wavelength division multiplexing/frequency division multiplexing (WDM/FDM) techniques and demonstrate that optical paths can greatly enhance the path layer capability and, therefore, network performance. It is shown that effective network failure restoration can be achieved with optical paths. The applicability of the wavelength path (WP) technique to global area networks is revealed. WPs are applied to the national backbone network example to evaluate the required number of wavelengths and to identify optical cross-connect node requirements. A new optical path concept is proposed, i.e., the virtual wavelength path (VWP). In the VWP scheme, wavelengths are assigned on a link-by-link basis. The wavelength assigned to a wavelength path has only local significance. Significant benefits of the VWP such as the simplified path accommodation design within a transmission facility network and the reduced number of wavelengths needed, are elucidated. >

Routing and switching in a wavelength convertible optical network

Abstract: A wavelength-convertible switch architecture and routing algorithm for circuit-switched wavelength-division-multiplexing optical networks is studied. Wavelength converters are used to resolve wavelength conflicts and to reuse wavelengths. These converters are not dedicated to individual channels, but are shared by the channels of a node or those of an outbound link in the share-per-node or the share-per-link wavelength-convertible switch, respectively. A routing algorithm is developed to converse wavelength converters while maintaining performance close to that of a network with abundant converters. It is found that converters can improve the network performance, such as the blocking probability and fairness, considerably. >

Fiber delay lines optical buffer for ATM photonic switching applications

Abstract: An optical buffer shift register based on a set of fiber delay lines is presented, with the goal of providing cell storage and queuing in asynchronous transfer mode (ATM) photonic switches. The concept of multiwavelength cell buffering is adopted, to realize a shared buffer with a storage capacity equivalent to a set of shift registers. Since only one wavelength-encoded cell must enter one delay line at each time slot, contention resolution is necessary to determine the queuing order between the incoming cells. The use of optical fibers as delay lines and semiconductor optical amplifiers as gates associated with passive splitters to realize buffering and time-switching has been demonstrated. An experimental setup has been implemented at 600 Mb/s and operates without guard bands between packets. The low penalty observed shows that system synchronization and reliability are good. >

Optical fiber tree and branch network for AM signal distribution

Abstract: The use of a doped optical fiber amplifier enables the transmission of multi-channel AM-VSB television signals. An Erbium doped fiber amplifier is disclosed. The amplifier is also useful for reducing second order distortion products produced in an amplitude modulated subcarrier optical communication system. The amplifier may be used in a tree and branch structure optical fiber television network.

New advances on optical components needed for FDM optical networks

Abstract: Two critical components, needed for optical networks based on frequency division multiplexing (FDM) and frequency reuse technologies, are presented. One is a fast tunable laser, yielding 24 discrete frequencies regularly spaced by 40 GHz around 1.53 mu m. The laser can be switched randomly in less than 8 ns among these frequencies. Frequency routing of a 3-Gb/s bit stream in 10-ns packets between ten different destinations has been demonstrated with this laser. The second component is a broadband wavelength shifter capable of switching multigigabit data between optical frequencies in the 1.5- mu m region. The device is tunable and cascadable, provides conversion gain, and is nearly polarization insensitive. Data degradation after wavelength shifting is negligible. Such a device provides the means of reusing the limited set of frequencies given by the lasers and thus of realizing large size networks. >