Optical amplifiers-light boosters in a chip

One potential way of building transmission systems able to accommodate capacity upgrades is to use optical amplifiers. These devices simply amplify the incoming optical signal. They are insensitive to the transmission bit rate and data format, have a broad optical bandwidth, and, in principle, pass signals in either direction. Optical amplifiers are thus highly flexible devices, potentially able to accommodate a wide range of improvements in the transmission system including increases in the bit rate, frequency-division multiplexing and coherent transmission. The author describes the construction of optical amplifiers and their operation including packaging, gain control and fault location. Their use in submarine links between the UK and mainland Europe is also discussed