title: Ultra-wide bandpass filter based on long-period fiber gratings and the evanescent field coupling between two fibers.
abstract: We demonstrate a fiber-based bandpass filter with an ultra-wide spectral bandwidth. The ultra-wide band feature is achieved by inscribing a long-period fiber grating (LPG) in a specially-designed low index core single mode fiber. To get the bandpass function, the evanescent field coupling between two attached fibers is utilized. By applying strain, the spectral shape of the pass-band is adjusted to flat-top and Gaussian shapes. For the flat-top case, the bandwidth is obtained ~ 160 nm with an insertion loss of ~ 2 dB. With strain, the spectral shape is switched into a Gaussian one, which has ~ 120 nm FWHM and ~ 4.18 dB insertion loss at the peak.
authors: Myoung Jin
authors: MJ
authors: Kim
authors: Yong Min
authors: YM
authors: Jung
authors: Bok Hyeon
authors: BH
authors: Kim
authors: Won-Taek
authors: WT
authors: Han
authors: Byeong Ha
authors: BH
authors: Lee