LED bandwidth of multimode fibers as a function of laser bandwidth and LED spectral characteristics

Equations have been developed that relate the bandwidth performance of 62.5-μm core diameter (
NA = 0.29
) graded-index multimode fiber when measured with LED sources to the LED's spectral characteristics and to the bandwidth measured with laser sources. Because the fiber's spectral loss characteristic filters the LED's power spectrum by shifting its center wavelength and narrowing its spectral width, these equations suggest that chromatic bandwidth scales more favorably than inverse linearly with length. The equations developed here have been used to predict hundreds of LED bandwidths measured independently both in the laboratory and in field installations. With typical agreement between these predictions and the measurements having an rms error of about 11 percent, these equations allow for system design and prediction of the bandwidth performance of LED-based multimode links.