Low-Cost Optical Data Link Design Study.

This paper discusses some of the theoretical background and practical problems involved in designing a full duplex 1.5 Mbsec optical data link. The actual design of a fiber-optic link and an atmospheric link is treated for an atmospheric path length of 1.372 Km and a fiber path length of 2 Km. Complete designs to the block diagram level are presented, and additional details are described for the modulator circuit for the CW laser diode and LED used in the atmospheric and fiber transmitters. Also presented is sufficient data to permit calculation of the various losses encountered in fiber and atmospheric links. It is shown that currently available LEDs and low-loss graded-index optical fibers should permit production of a 2 Km long fiber optic data link to handle a data rate of 1.5 Mbs with an error rate of less than 10 to the minus 5th power.