All-Fiber Bandpass Filter Based on Helicoidal Long-Period Grating Pair and Null Core Hollow Optical Fiber With Flexible Transmission Control

• Published in: IEEE photonics technology letters Vol. 20; no. 2; pp. 153 - 155
• Main Authors: Shin, W., Oh, K., Yu, B.-A., Lee, Y.L., Eom, T.J., Noh, Y.-C., Ko, D.-K., Lee, J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.01.2008; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Band pass filters; Bandpass filters; Concatenated codes; Core loss; Devices; Diffraction gratings; Fiber gratings; Fiber optics; Gratings (spectra); optical communication; Optical control; optical fiber applications; optical fiber device fabrication; Optical fiber devices; optical fiber filters; Optical fiber polarization; Optical fibers; Photonics; Photorefractive effect; Propagation losses; Spectra; Thermal stresses
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2007.912498

We report an all-fiber bandpass filter (BPF) based on a null core hollow optical fiber serially concatenated between a pair of helicoidal long-period fiber gratings (HLPFGs) with flexible transmission control capability. With novel spectral functionality of HLPFGs that can be varied by the torsional stress to the helix, and core mode blocking in a hollow core fiber, the proposed device showed unique BPF characteristics whose transmission can be flexible and altered along with a low polarization-dependent loss and low thermal variation, which have not observed in prior photorefractive grating devices.