Add-Drop Filter Based on Microfiber Mach–Zehnder/Sagnac Interferometer

In this paper, we investigate and experimentally demonstrate a Mach-Zehnder/Sagnac loop mirror interferometer (MZ-SI) fabricated from microfiber. We introduce a simple fabrication technique to assemble a miniatured MZ-SI from a single microfiber which can be used as an add-drop filter. The through and drop port transmission spectra of this microfiber structure are analyzed and they are in agreement with the theoretical model. The pattern of interference in the transmission spectra can be controlled by manipulating the parameters of this microfiber structure.