Easy fabrication of long‐period fiber grating by winding a wire around an optical fiber fixed to cylindrical ROD

A new approach is presented for the easy fabrication of wire-winding long-period fiber grating based on the periodic winding of a wire around an optical fiber attached to a cylindrical rod. The periodic pressure of the wire induces change of the refractive index of the optical fiber core, and so the resonance wavelengths of the grating can be easily controlled according to the winding-wire pitch controlled by a microprocessor. At the winding-wire pitch of 500 mu m, the spectra show resonancewavelength dips corresponding to the LP02, LP03, LP04, and LP05 cladding modes; the resonance wavelengths go to longer wavelengths at the increased winding pitch of 510 mu m; these are in good agreement with theoretical values. The polarization dependence of a resonance wavelength shift of 9 nm and transmission power difference of 2.5 dB was shown at the 520 mu m grating pitch. When the diameter of the cylindrical metal rod was smaller, or higher tension by the winding pressure was applied, stronger mode coupling resulted in deeper dips in the transmission spectra according to induced higher index variation. (C) 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:19371941, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26951