Power profiles, along with variations in fiber uniformity, can cause modal dispersion which is measured by differential modal delay (DMD). Modal dispersion is caused by the different speeds of the individual modes in a light pulse. The net effect causes the light pulse to spread over distance, introducing intersymbol interference. The greater the length, the greater the modal dispersion. his resulted in the development of Laser Optimized Multi-Mode Fiber (LOMMF) to counter the effect.

Differential Modal Dispersion DMD is a measurement of multimode fiber bandwidth.