L.C. Blank

Optical time domain reflectometry on optical amplifier systems

The use of optical time-domain reflectometry (OTDR) on long-span fiber transmission systems containing in-line optical amplifiers is discussed. Having identified the specific requirements for OTDR equipment, measurements were carried out on systems of up to 300 km in length, containing three semiconductor laser amplifiers. The results demonstrate that OTDR can be used not only for fault location on fiber links several hundred kilometers in length but also as an alternative to standard system supervisory techniques, thus providing the potential for minimizing the hardware in the optical amplifier stages of future long-span fiber optic transmission systems. >

Optical multiplexing techniques for future Gbit/s transmission systems

Optical multiplexing is considered for gigabit-per-second (Gb/s) long distance transmission networks with emphasis on applications for which optical techniques can offer remote signal processing using passive components. Experimental transmission systems, operating at multi-Gb/s line rates and using both optical-time-division multiplexing and wavelength-division multiplexing are described. Particular attention is given to demonstrating realistic practical systems, emphasizing control and the use of commercially available components.<<ETX>>

Transmission and signal processing techniques for gigabit lightwave systems

The technology of optical-fiber transmission systems has advanced rapidly within recent years; a number of laboratories having reported gigabit transmission over 100-km spans. These developments have placed increasing emphasis on the associated signal processing functions such as timing extraction and regeneration. This paper will review laser, fiber, and receiver requirements for high-speed systems and describe two recent lightwave transmission experiments featuring distributed feedback lasers, low-loss dispersion-shifted fiber, germanium avalanche photodiode receivers, and gallium arsenide logic devices.

Long span optical transmission experiments at 34 and 140 Mbit/s

Long-haul optical fiber transmission system experiments have been carried out over unrepeatered spans up to 250 km. In this paper the design options for such systems will be discussed, followed by a description of five laboratory trials: a dispersion-limited 176-km 34- Mbit/s experiment, employing commercial components throughout; two loss-limited system trials over 220 km at 140 Mbit/s and 233 km at 34 Mbit/s, based on multimode lasers and dispersion-shifted fiber; and a further two experiments over 223 and 251 km at the same line rates, featuring single-line DFB lasers and step-index monomode fiber.

High electron mobility transistor lightwave receiver for broad-band optical transmission system applications

The design and construction of a broadband transimpedance lightwave receiver which features packaged, commercially available high-electron-mobility transistors is described. The receiver was constructed on a standard teflon printed circuit board with packaged tailed 30- mu m-diameter germanium avalanche photodiode as photodetector. A sensitivity of -25.5 dBm for 10/sup -9/ bit error rate was achieved at 1.31 mu m with a 5-Gb/s nonreturn-to-zero pseudorandom sequence provided by a commercial data generator and 1:4 analog demultiplexing at the receiver output. >

High-speed optical regenerator chain simulation by jitter synthesis

With the current trend toward higher capacity in regenerated optical transmission systems (e.g., Ref. 1), increased emphasis has been placed on the jitter characteristics of such links. A number of jitter measurement experiments have been reported which feature either cascaded electrical2 or looped optical regenerators.3,4 Both techniques have disadvantages as practical system simulation tools. Regenerator cascades are expensive to implement, while regenerator jitter transfer functions cannot be conveniently modified while loop experiments are in progress.

Progress In Long-Span, High-Capacity Optical Transmission System Research

Direct detection single mode optical fibre systems have evolved rapidly during recent years such that multigabit transmission has now been demonstrated over 100 km spans. At lower line rates, unrepeatered optical path lengths in excess of 250 km have been reported. This progress is largely due to technical advances such as narrow spectral line lasers, low-loss step-index and dispersion-shifted fibre together with high-sensitivity, broad-band receivers. The high speed system developments have placed increased emphasis on the associated signal processing functions such as timing extraction and regeneration, this latter function being provided with gallium arsenide logic devices. This paper will review some aspects of the high-speed and long-span transmission experiments carried out at BTRL. These include an ultra-long-span, 34 Mbit/s system and a 2.4 Gbit/s fully-regenerated high-speed optical transmission test over an installed 32 km fibre.