Baud rate response: characterizing modal dispersion for digital fiber optic systems

A method of characterizing modal dispersion in optical fibers, for baseband digital applications, is developed. Pulse distortion due to modal dispersion is simulated using modal transfer functions and pseudorandom pulsetrains. The extent of the distortion at given baud rates is identified with eye diagrams. Received optical power penalties are calculated from eye diagrams for a spectrum of baud rates, resulting in a penalty-versus-baud rate function called a baud rate response (BRR). Three useful parameters are derived from the BRR. The BRR magnitude parameter and shape parameter are used accurately to calculate a fiber´s modal-dispersion power penalty for any given baud rate. The maximum baud-rate length product provides a mechanism for specifying modal dispersion quality along fibers