LOCNET--A local area network using optical switching

A wide-band local area network using optical switching is presently being developed by the Heinrich-Hertz-lnsitut in Berlin (West). To ensure high reliability the system will be implemented as a star type network, divided into two subsystems. All switching within the system will be done by optical switching techniques. The wide-band subsystem will use Lithium-Niobate switching matrix elements, interconnected as a multistage space switch. Thus bit rate independent channels will be available with the ability to establish various wide-band services of the in-house area. The second subsystem makes use of a single-mode star coupler. Distributed circuit switching with fast switching capability and flexible data rates will be implemented, utilizing a TDM frame, that supports 63 narrow-band connections and a capacity of 8 Mbit/s for fast data services. To prevent typical disadvantages of distributed switching like line tapping and system disturbance, caused by malfunctioning system components, LiNbO3switches will be installed in front of and behind the star coupler. The single-mode star coupler will be implemented by cascading 2 × 2 star couplers, which are available as 3-dB couplers.