PMD in a fiber cable increases with time due to weather in the cable. As it increases, the cable becomes less usable until a time it crosses the PMD tolerance of the equipment installed to use the cable hence the cable deteriorates at some rate. Is the Arrhenius model the best to apply while determining this? are there other models?
To reinforce what Vincent has said, are you certain you are observing degradation of the cable, and not simply the small random changes in local birefringence and polarisation mode coupling expected in any cable?
How are you measuring the PMD? If the DGD is sufficiently high to cause problems, you need to know whether there is a systematic change in the mean, rather than fluctuations in the instantaneous DGD. One approach is to measure DGD as a function of wavelength and over as broad a spectral range as possible, and repeat this at regular intervals for an extended period.
Regarding an Arrhenius model, you need a very thorough understanding of the degradation mechanism to provide theoretical values for the activation energy and rate constant. Alternatively you need systematic measurements of the rate of change of DGD and the change of mean PMD as a function of temperature. For such an intrinsically random process, this would require a very large number of individual DGD measurements. It may be simpler to find a supplier with a more suitable cable design.
Alan.
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