An architectural approach that meets high bandwidth requirements by introducing a communication architecture based on lightpaths, optical transmission paths in the network, is introduced. Since lightpaths form the building block of the proposed architecture, its performance hinges on their efficient establishment and management. It is shown that although the problem of optimally establishing lightpaths is NP-complete, simple heuristics provide near optimal substitutes for several of the basic problems motivated by a lightpath-based architecture. >

Lightpath communications: an approach to high bandwidth optical WAN's

A system of distributing video and/or audio information employs digital signal processing to achieve high rates of data compression. The compressed and encoded audio and/or video information is sent over standard telephone, cable or satellite broadcast channels to a receiver specified by a subscriber of the service, preferably in less than real time, for later playback and optional recording on standard audio and/or video tape.

Audio and video transmission and receiving system

The system issues and network applications of acoustooptic tunable filters (AOTFs) are discussed. AOTFs are thought to be attractive system components in dense wavelength-division multiplexed (WDM) networks because of their broad continuous electronic wavelength tunability and narrow filter bandwidth. Their unique multiwavelength filtering capability adds a greater dimension of flexibility to network design. The characteristics of the AOTF are reviewed from a system viewpoint and the performance and capabilities of bulk-devices, integrated-optic devices, and fiber-based devices are discussed and compared. Three network applications using the acoustooptic tunable filters are described. The first application is as wavelength-tunable receivers or taps for local users in a subscriber loop distribution network. The second is as multiwavelength tunable receivers in a broadcast local-area cross-connect for packet communication with very-high-throughput data rate. The third is as wavelength-selective space-division switch fabric for routing and cross-connect between central offices. Future prospects and various issues for future research are also discussed. >

Acoustooptic tunable filters in narrowband WDM networks: system issues and network applications

Applications for erbium-doped fiber optical amplifiers have been multiplying in recent years, and increasingly complex structures have been introduced. We review characteristics and design parameters, the use of interstage elements, and various digital transmissions systems applications for multi-stage amplifiers. A notation is introduced to describe multi-stage fiber amplifiers. >

Multi-stage erbium-doped fiber amplifier designs

A balanced doped fiber optical amplifier is disclosed which requires only a single wavelength division multiplexer to provide pump and signal inputs to multiple amplifier stages. In particular, a first section of doped fiber is coupled to an "input" port of the multiplexer and a second section of doped fiber is coupled to an "output" port of the multiplexer. First and second pump signals are coupled to the remaining ports to provide a counter-propagating pump signal to the first doped fiber section and a co-propagating pump signal to the second doped fiber section. The parameters of each doped fiber section (e.g., length, dopant concentration, pump power, pump wavelength) may be individually tailored to provide the desired results (pre-amplification or power boosting, for example). A plurality of balanced optical amplifiers may be cascaded to provide multi-stage amplifiers, and the pump signal levels may be controlled to provide gain equalization. Preferably, the balanced amplifier is spliceless and comprises only two sections of doped fiber, the multiplexer formed as a coupling region between the fibers.

Balanced optical amplifier

The simultaneous amplification of 16 distributed feedback (DFB) lasers over a 34-nm spectral range in an erbium-doped fiber amplifier is reported. Sixteen DFB lasers spaced at approximately 2-nm intervals and covering 34 nm in the 1.55- mu m band were modulated with a total of 100 studio-quality analog FM-TV channels and six 622-Mb/s channels. >

Simultaneous distribution of multichannel analog and digital video channels to multiple terminals using high-density WDM and a broad-band in-line erbium-doped fiber amplifier

A limiting optical amplifier is demonstrated using three cascaded stages of erbium-doped fibre amplifiers. A constant output power of +12.9 dBm was obtained for an input power ranging from −30 to 1.5 dBm. The optical noise figure of the amplifier has been measured over the >30 dB dynamic range. Design guidelines for optical limiting amplifiers are also presented.

High gain limiting erbium-doped fibre amplifier with over 30 dB dynamic range

Distribution of 100 FM-TV Channels and Six 622 Mb/s Channels of 4096 Terminals Using High-Density WDM and A Broadband In-Line Erbium-Doped Fiber Amplifier

Germanium-, phosphorous-, and aluminium-containing silica glasses have been extensively used as hosts for lanthanide-series rare-earth-doped fiber lasers and optical amplifiers.1,2 Er3+-doped fiber lasers and optical fiber amplifiers are of particular interest because their spectral emission falls in the ultra-low-loss transmission region of high-silica single-mode fibers. It is now well established that Al-codoped fibers2 provide a broader spectral bandwidth and permit higher Er3+ doping concentration.

Er3+-doped GeO2-CaO-Al2O3 silica core fiber amplifier pumped at 813 nm

Optical limiting amplifiers (OLA's) provide a high constant output power for a wide range of input power variations. Therefore, OLA's based on erbium-doped fiber amplifiers (EDFA's) may find applications in transmission and distribution networks. For example, OLA's with a large dynamic range can be used as a power amplifier, an in-line amplifier, or a preamplifier in a subscriber loop or a long-haul system, where distribution/transmission losses vary significantly from location to location [Fig. 1(a)]. On the other hand, OLA's can be used to equalize the unequally received power from different terminals in a switching network [Fig. 1(b)]. In this paper, we report on an OLA with more than 30 dB of dynamic range. It provides a constant output power of +12.9 dBm for an input power varying from −30 to +1.5 dBm. The noise figure for this OLA has also been examined.

A. Von Lehman

Papers

Simultaneous distribution of multichannel analog and digital video channels to multiple terminals using high-density WDM and a broad-band in-line erbium-doped fiber amplifier

High gain limiting erbium-doped fibre amplifier with over 30 dB dynamic range

Distribution of 100 FM-TV Channels and Six 622 Mb/s Channels of 4096 Terminals Using High-Density WDM and A Broadband In-Line Erbium-Doped Fiber Amplifier

Er3+-doped GeO2-CaO-Al2O3 silica core fiber amplifier pumped at 813 nm

High-gain-limiting erbium-doped fiber amplifier with over 30 dB of dynamic range