TABLE OF CONTENTS Optical fiber use in telecommunications has matured beyond a basic point-to-point system. The optical signals by themselves are now multiplexed with other signals, switched, and re-routed. Achieving this requires many different optical components. The major components discussed here are:
connectors
splices
couplers/splitters
wavelength division multiplexers (WDM) and filters
circulators
isolators
attenuators
switches
modulators
The first four of these devices are passive. A passive device does not require energy from a power supply or an added signal input. All devices have fiber input/output ports and are fabricated from fibers, integrated optics, or micro-optic components in various combinations. The devices that use fibers alone are the cheapest to produce. Sometimes these components require externally applied fields. Integrated optic devices use optical waveguides implanted in substrates. Microoptic devices use lenses, filters, and gratings. Because microoptic components must be small and stable, they are the most costly to produce. However, they also can be made to be more wavelength sensitive, which makes them attractive for optical multiplexing/demultiplexing.
Connectors afford flexibility in routing fibers and are generally used in terminal equipment. They are attached to the fibers either in the field or the factory. Splices are used to make permanent connections between fibers and can also be field or factory installed. Splices are used in place of connectors whenever possible because connectors have more insertion loss, and are more prone to failure. Couplers, which are generally bi-directional, are...
