Carrier relaxation time divergence in single and double layer cuprates

We report the transient optical pump-probe reflectivity measurements on single and double layer cuprate single crystals and thin films of ten different stoichiometries. We find that with sufficiently low fluence the relaxation time (tau(R)) of all samples exhibits a power law divergence with temperature (T): tau(R proportional to) T-3 +/-0.5. Further, the divergence has an onset temperature above the superconducting transition temperature for all superconducting samples. Possible causes of this divergence are discussed.