Saving entangled photons from sudden death in a single-mode fiber ---- Interplay of decoherence and dynamical decoupling.

We study the dynamics of decoherence in an optical fiber for the case of entangled photons. Such a study will allow us to increase the physical length of fiber for the transmission of entangled photon from the sources such as SPDC. We analytically derive the model for decoherence of entangled state photons in a single-mode fiber. We also show that entanglement lifetime can be increased with open loop control technique called dynamical decoupling.