Frequency-Agile Fiber-Optic Transceivers

Fiber-optic transceivers (FOTs) that can handle digital signals at any bit rate from 10 to 300 MHz have been developed. These variable-rate FOTs offer considerable advantages over fixed-rate FOTs that have been used until now. A fixed-rate FOT contains clock- and data-signal-recovery circuits tuned to the data rate. In a system in which data streams are transmitted at different rates, the data rates must be specified in advance, and a separate fixed-rate FOT must be designed, constructed, and installed for each rate. Thus the cost of acquiring, maintaining, and operating fixed-rate FOTs for a multiple-rate system can be high, and under some circumstances, advance notice of data rates could compromise security. Obviously, costs can be reduced and security enhanced by use of variable-rate FOTs capable of operating over the full range of data rates.