Patrick R. Trischitta

9000 km, 5 Gb/s NRZ Transmission Experiment Using 274 Erbium-Doped Fiber-Amplifiers

The next generation of undersea transmission systems will use Erbium-doped fiber amplifiers (EDFAs) to boost signals periodically as the signals travel across the world’s oceans[1] [2] AT&T and KDD have constructed a joint experiment to aid in the design of the first trans-Pacific optical amplifier cable[3] To date, straight line experiments have been reported up to 4500 km.[4] [5] This memorandum reports error- free performance at 5 Gb/s, through 9000 km of dispersion shifted fiber and 274 EDFAs.

The SL Undersea Lightwave System

The SL Undersea Lightwave System is a large capacity digital fiber-optic transmission system capable of spanning the worlds largest oceans and seas. The system is now being manufactured for use in teleconmmunications systems planned for the Atlantic and Pacific Oceans. In this paper we will discuss how the risks associated with using relatively new lightwave technology were minimized to design a digital undersea communication system which excels in reliability, availability, and perform mance.

A 9000 km 5 Gb/s and 21,000 km 2.4 Gb/s Feasibility Demonstration of Transoceanic EDFA Systems Using a Circulating Loop

The capacity of transoceanic undersea transmission systems can be greatly increased by using erbium-doped fiber amplifiers (EDFAs) as undersea repeaters. Of the many transmission ‘experiments that have been performed using EDFAs,[1] [2] [3] the longest distance achieved to date transported a 2.4 Gb/s signal through a 2,200 km fiber that contained 25 EDFAs spaced every 80 km.[1] Extending the transmission length-of these experiments would require a large amount of hardware. Therefore, we have chosen to show feasibility of transoceanic EDFA systems by measuring the bit error rate (BER) after multi-thousand kilometer transmission using a circulating loop.

The SL Undersea Lightguide System

A digital optical fiber undersea cable system targeted for transatlantic service in 1988 is now under development at Bell Laboratories. The system uses single-mode fibers to carry data at a bit rate of 280 Mbits/s. Using digital speech compression techniques, a total system capacity of over 35 000 two-way voice channels can be realized. With laser transmitters at 1.3 μm, repeater spacings are expected to exceed 35 km. This paper discusses system parameters, repeaters, fiber and cable design, terminal equipment, and system measurements.

The accumulation of pattern-dependent jitter for a chain of fiber optic regenerators

The experimentally validated linear, shift-invariant jitter model of an individual fiber-optic regenerator is used to derive the jitter accumulation model for a chain of nonidentical fiber-optical regenerators. The jitter characteristics of 40 regenerators are measured individually and are used as parameters in the jitter accumulation model. The calculated accumulation is compared to an accumulation measurement made along a chain of these same 40 regenerators to estimate the portion of pattern-dependent jitter that accumulates systematically. >

A circulating loop experimental technique to simulate the jitter accumulation of a chain of fiber-optic regenerators

A circulating-loop experimental technique to simulate the jitter accumulation of a chain of fiber-optic regenerators is described. This technique allows system designer to establish the jitter accumulation characteristics of systems without the need for many test regenerators. An analytic description of how well the loop technique simulates a china of identical fiber-optic regenerators is presented along with a comparison of calculated and simulated jitter accumulation. >

The Jitter Tolerance of Fiber Optic Regenerators

In this paper, we will analyze the effect accumulated jitter has on the decision making process inside the N th fiber optic regenerator of a long chain of fiber optic regenerators. The criteria for a correct bit decision in the presence of receiver noise, static phase offset, and accumulated input jitter will be derived, and calculations of the bit error rate penalties caused by the presence of known distributions of accumulated input jitter will be made. We will then define the jitter tolerance of a fiber optic regenerator as an effective measure of the regenerators capability to tolerate incoming accumulated jitter. We will show that excessive bit error rate penalties will not occur if the accumulated input jitter does not exceed the regenerators measured jitter tolerance template. Finally, the jitter tolerance measurement technique will be used to find the optimum sampling time inside a fiber optic regenerator resulting in a regenerator that is optimized for use in long-haul systems.

Global undersea networks

Summary form only given. Starting last year, a new generation of undersea systems using the latest fiber-optic and network technology began being installed worldwide and will, upon completion by the turn of the century, transform the international communications grid into truly global undersea communication networks. This paper discusses six such networks and describes how these networks will transform the business of providing international communication services by lowering costs and increasing available services bandwidth. This paper will also bring into focus how new technologies such as wavelength-division multiplexing (WDM) can be applied to enhance and expand communication services on these installed networks.

Feasibility demonstration of transoceanic EDFA transmission systems (Invited Paper)

We have demonstrated the feasibility of transoceanic fiber amplifier systems using an experimental technique that measures bit error rates in a circulating loop. We have achieved a transmission distance of 9,000 km at 5 Gb/s and 21,000 km at 2.4 Gb/s using a non-retum-to-zero pseudo-random data pattern. The bit rate distance product of the 2.4 Gb/s result was 51 Tb-km/sec.

The SL Undersea Lightwave Transmission System

A new alternative in transoceanic communication is now in production at AT&T which will provide several key advantages for the military cammunicator over existing ways of communicating across the Atlantic and Pacific Oceans. The SL Undersea Lightwave Cable System, which will be a major part of the TAT-8 and TPC-3 cable systems, will offer the military user several advantages over satellite transoceanic communications. ¿No delay or echo effects on both voice and data channels. ¿Lower system cost, longer system lifetime. ¿Immunity from atmospheric disturbances, multipath fading, etc. ¿Jam proof. ¿Extremely difficult to tap without system failure.