effective modal bandwidth (OM) (EMB)
The mode bandwidth of optical fibers is limited by mode dispersion and chromatic dispersion and is determined by the optical power spectrum. The mode bandwidth is the frequency at which the amplitude of the light signal has decreased by three decibels( dB) compared to the reference level.
The mode bandwidth corresponds to the bandwidth length product, expressed in bandwidth x distance( MHz x km). It indicates the maximum data rate over a given distance, or, in other words, the maximum distance that can be covered at a given data rate.
Effective Modal Bandwidth (EMB) is a characteristic value of optical fiber transmissions. The EMB value is used synonymously with the mode bandwidth and is composed of the properties of the light source, i.e. the light emitting diode or the VCSEL laser, and the optical fiber. It is the frequency at which the amplitude of the light signal has decreased by three decibels (dB) from the reference level. The previously calculated effective mode bandwidth is called the calculated mode bandwidth EMBc (Calculated) or miniEMBc.