CIRCULATING LOOP TRANSMISSION EXPERIMENTS FOR THE STUDY OF LONG-HAUL TRANSMISSION-SYSTEMS USING ERBIUM-DOPED FIBER AMPLIFIERS

A circulating loop transmission experiment is a useful tool for the re search and development of long-haul transmission systems that use Erbi um-doped fiber-amplifier repeaters. Circulating loop techniques, appli ed to an amplifier chain of modest length, can pro,ide an experimental platform to study a broad range of transmission phenomena for EDFA-ba sed transmission systems. A loop experiment attempts to simulate the t ransmission performance of a multi-thousand kilometer long system by r eusing or recirculating an optical signal through a modest length ampl ifier chain of tens to hundreds of kilometers. This paper reviews orig inal loop techniques developed to study various parameters of long-hau l transmission using Erbium-doped fiber-amplifiers repeaters for under sea systems. Transmission experiments were performed at transoceanic d istances with 33 and 46 km amplifier spacing, operating at 5 and 10 Gb /s. Experimental data is provided here for various parameters, includi ng bit error ratio, Q-factor, and spectral broadening.