Coherence tuned fiber optic sensing system, with self-initialization, based on a multimode laser diode.

In this paper we study the potential of using multimode laser diodes as an alternative to low coherence length sources normally used white light fiber optic interferometric sensors. A simple theoretical model is introduced to demonstrate the autocorrelation function of such sources. An experimental setup of two interferometers in tandem was used to study the coherence properties of the multimode laser diode Mitsubishi ML-4406 and then to demonstrate the possibility of using it in coherence tuned multiplexing systems. The main advantage of using such sources is to launch more optical power into the monomode fiber and hence to improve the system resolution.