Optical Fiber Devices in Lightwave Systems,

Fiber devices in fiber transmission systems became more important than micro-optic devices from view point of reliability, low insertion loss and price. Significant requirement in recent fiber transmission systems is high return loss close to 50 dB as well as low insertion loss and this accelerates importance of fiber devices. In this paper, fiber devices mainly in NTT systems are presented. Before reviewing them, it is necessary to define the fiber devices as follows a they have no lens, and b they are alignment free devices even if bulk elements are attached toor the fibers.