Microfiber interferometer with surface plasmon-polariton involvement.

We fabricated a microfiber interferometer with surface plasmon-polaritons (SPPs) involvement. Commonly, the SPPs are not involved in interference due to the mismatch momentum and ultrashort propagation distance. In this Letter, an absorber-doped microfiber is utilized for increasing the matched momentum (i.e., their modal projection), and as a result, an SPP is coherent with an end-fire method-stimulated hybrid SPP. A mathematical model is proposed for investigating the modal-projection-caused interference, and its results show that the proposed interferometer is very dependent on the polarization. Confirmation experiments were carried out, and a good agreement between theoretical predictions and experimental results was found. The proposed interferometer will potentially facilitate many SPP studies in directly related fields.