An equal channel spacing Sagnac filter is proposed using a high-birefringent photonic crystal fiber (PCF) with birefringence square to the operation wavelength. A PCF with four smaller central air holes surrounded by larger air holes is applied in a Sagnac filter with optimized parameters to achieve equal channel spacing of 0.8 nm. Given that the birefringence of this PCF is square to the operation wavelength, the channel spacing of the proposed filter changes by only 0.03 nm within a wavelength range from 1400 to 1650 nm; this is about one order of magnitude less than that constructed with conventional high-birefringent fibers.
© 2010 Chinese Optics Letters
(060.2330) Fiber optics and optical communications : Fiber optics communications
(060.2340) Fiber optics and optical communications : Fiber optics components
(060.2420) Fiber optics and optical communications : Fibers, polarization-maintaining
(230.7408) Optical devices : Wavelength filtering devices
Xiurong Ma and Ying Zhu, "Equal channel spacing Sagnac filter using high-birefringent photonic crystal fibers," Chin. Opt. Lett. 8, 983-985 (2010)