An microfiber-based integrated interferometer comprises a Sagnac loop formed at one end by bending a microfiber to form the loop and a pair of extensions stretching away from the loop thereof; a first optical coupling structure and a second optical coupling structure, formed by intertwining the pair of extensions; a Mach-Zehnder interferometer constituted of a pair of arms, a first arm and a second arm, spanning in between the first and second optical coupling structures that the first and second arms are unequal in length; a light input and light throughput respectively constituted of the pair of extensions projecting from the second optical coupling structure; and a drop port, characterized in that the drop port is positioned at the light input; whereby the transmission spectra of the integrated interferometer is adjustable via varying dimension of the first optical coupling structure and the length difference in between the first and second arms.