  We analytically derive a decoherence model for orbital angular momentum
states of a photon in a multimode optical fiber and show that rate of
decoherence scales exponentially with $l^2$, where $l$ is the azimuthal mode
order.~We also show numerically that for large values of $l$ the orbital
angular momentum photon state completely dephases.~However for lower values of
$l$ the decoherence can be minimized by using dynamical decoupling to allow for
qudit high-bandwidth quantum communication and similar applications.
\end{abstract}
