Optical circulating loop experiments

A circulating loop set-up was initially made to support 2.5 Gbit/s transmission. It has been upgraded to 10 Gbit/s by constructing a clock recovery system and employing a HP test set with gating capabilities. In order to monitor eye diagrams for a specific distance a trigger gate for triggering an oscilloscope was build.
The loop experiment was further upgraded with a new loop switch consisting of three acousto-optic modulators used as optical switches and passive optical couplers. This new loop switch provides a large on-off ratio with low insertion losses independent of polarization and wavelength.
Initially the circulating loop set-up was used for simulating very long distance transmission using in-line amplifiers. Although investigations of specific amplifier configurations in long distance transmission is still a topic, the study of cascading WDM components has become a growing and important part of the experimental work which uses the loop set-up as the test bed. Cascading of components like WDM filters, optical add/drop multiplexers and optical wavelength converters have been investigated. Also subsystems (e.g. a partly equipped optical cross-connect) have been investigated.
Long-haul multi-channel transmission with a total capacity of 100 Gb/s using Raman amplification was investigated in cooperation with Tyco Submarine Systems Ltd. in their loop testbed during the external visit of Ph.D. student Morten Nissov. Record performance was achieved.
In 1997 the main responsibility of the EMI loop experiment was transfered to Fenghai Liu.
Publications: P1340, P1373, P1450, P1452, P1454, P1437, P1481
The project has been moved to COM by Dec. 31, 1998.