By Carl J. McGrath, AT&T Bell Laboratories
In the past 12 months practical multi-channel AM fiber optic links have moved from the R&D lab into real world applications. In this paper, we focus on the design, characterization and performance capabilities of systems intended for use with signal spectra covering 20-80 CATV channels using distributed feedback (DFB) laser diodes and single mode optical fiber.
We discuss first the fundamental concepts used in a direct modulated AM laser based communications link. The noise and other degradation sources are identified and techniques used in mitigating their affects on performance are presented. Measurement techniques and practical results are also discussed.
We then discuss results on several laboratory demonstrations and field installations using the broad band AM link technology, with attention to the implementation issues faced by operators in the real-world environment of CATV networks.