Fiber Optics: Fiber Optic Amplifiers

Joe Calvitti and Bryan Rothermel, Lucent Technologies

Optical amplifiers will soon become smarter.

To meet dense wavelength division multiplexing needs, erbium-doped fiber amplifiers boost optical signals across multiple wavelengths. As communications systems add more wavelengths, however, erbium-doped fiber's challenges are becoming increasingly apparent.

Erbium-doped fiber amplifiers are assemblies of devices, including pump lasers, passive components, erbium fiber and a microprocessor. As such, their manufacture represents an inherently difficult, labor- and test-intensive assembly process. They are also expensive and noisy. When they manage substantial traffic at speeds of 2.5 to 40 Gb/s, as in long-haul communications, their cost is reasonable.

In the future, the goal is to create an optical amplifier manufacturing platform that integrates individual optical components such as isolators, wavelength combiners and splitters, and pump modules. This would produce devices that can accomplish such tasks as power monitoring with photodetectors. Future manufacturing must be flexible enough to satisfy diverse customer specifications while achieving economies of scale in the manufacturing process. To do this, the manufacturing must be automated, modular and repeatable.