Optical access couplers and a comparison of multiterminal fiber communication systems

Optical T and multiple T access couplers designed for tapped trunk line multiterminal communication systems that use bundles of multimode fibers as the transmission media have been investigated. The particular coupler designs tested used bent Pyrex rods for bifurcation and scrambling. Coupler throughput losses (not counting packing fraction losses) are 1.5-2.5 dB. The bent rod optical T and multiple T access couplers must be used with high N.A., low packing fraction loss fibers. To avoid the use of a repeater a multiple T or star configuration must be used in a system comprising ten or more terminals.