A Tunable-Transmission Sagnac Interferometer Using an Optical Microfiber

This paper deals with fabrication of an optical microfiber and demonstration of a Sagnac loop interferometer constructed with it. An optical microfiber with a diameter similar to 2 mu m and loss similar to 0 03 dB/mm is manufactured by tapering a conventional single-mode fiber using a flame-brushing technique A Sagnac interferometer is assembled by twisting the fabricated microfiber into a loop The intertwisted section of the loop functions as a directional coupler whose coupling ratio is tunable by changing the twist rate. Transmission characteristics of the interferometer may allow us to use it as a potential photonic device such as a linear edge filter, an optical variable attenuator, or a gain flattening filter. (C) 2010 The Japan Society of Applied Physics