Optical switch and lD devices for future optical subscriber loop systems.

Introduction of optical switches and laser diodes (LDs) to optical subscriber loop systems is discussed. An optical switch for fault testing is presented for upcoming subscriber loop systems. It can connect a pair of probe fibers to any one of 48-channel subscriber-line fibers. Insertion loss in a normal state is 0.79 dB. An LD optical amplifier and LD wavelength selector are discussed as elements for future subscriber loop systems. Characteristics of the devices for wavelength-division-multiplexing transmission are reported.