We demonstrate implementation of an all-fiber Mach–Zehnder interferometer formed in a photonic crystal fiber (PCF). We formed the all-PCF Mach–Zehnder interferometer by mechanically inducing two identical long-period fiber gratings (LPGs) in the PCF. The spectral properties of a LPG and a LPG pair were investigated. The interference fringe formed within the stop band of the LPG pair varied with the period and the strength of the gratings, and the fringe spacing was decreased with increasing grating separation. From the fringe spacing measurement the differential effective group index of the PCF was calculated to be Δ<i>m</i>∼2.8×10<sup>-3</sup> .
© 2004 Optical Society of America
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.2340) Fiber optics and optical communications : Fiber optics components
(230.0230) Optical devices : Optical devices
(350.2770) Other areas of optics : Gratings
Jong H. Lim, Hyun S. Jang, Kyung S. Lee, Jin C. Kim, and Byeong H. Lee, "Mach-Zehnder interferometer formed in a photonic crystal fiber based on a pair of long-period fiber gratings," Opt. Lett. 29, 346-348 (2004)