Optical fiber based components

Optical fibers are currently one of the key elements in the development of telecommunications, and have enabled the advent of high and then very high data rates in optical communications, where signals (telephony, data, television) are transmitted to a light source and then carried by optical fibers to a detection system. Progress has continued unabated, with chromatic multiplexing (DWDM: Dense Wavelength Division Multiplexing) now available for terabit/s transmission. Optical fibers are also used in other fields: instrumentation, endoscopy, sensors, avionics, lighting....

The advantages of optical fibers are numerous: high transmission capacity, absence of interference between parallel links (crosstalk), very low signal attenuation, insensitivity to electromagnetic interference, electrical insulation, transmission integrity, low weight, small footprint.

The development of optical telecommunications requires end components such as sources and detectors, as well as passive components for signal routing and processing. Passing light from one conductor to another is a relatively delicate operation, requiring the use of special components such as connectors and couplers. Although great strides have been made with the advent of soldering machines and new-generation connectors, implementation requires appropriate training of personnel.

When transmission capacities are important, the use of in-line optical components, such as optical amplifiers, is an obvious advantage. Similarly, the development of multiplexers/demultiplexers has made it possible to transmit several wavelengths on a single fiber.

Finally, carrying signals over ever longer distances at ever higher data rates means that phenomena such as chromatic pulse broadening and polarization dispersion become non-negligible. This has led to research and development into high-performance compensating components.

The aim of this article is to provide an overview of components based on optical fibers. It will cover coupling problems, passive systems, amplifier systems and systems based on non-linear optics.