Simulation of optical FM direct detection transmission systems

Abstract

Conventionally, optical intensity modulation (OOK, On-Off-Keying) is the common technique used in optical communication links. It is achieved by varying the drive current from a value just below threshold to a desired high level above the threshold. However, the resulting modulation is a mixture of amplitude and frequency modulation. The laser output is chirped during the turn-on transient which broadens its spectrum and leads to undesirable pulse dispersion as the light travels through a dispersive optical fiber.