Fabrication and Characterization of a Broadband Long-Period Grating on a Hollow Optical Fiber with Femtosecond Laser Pulses

Abstract

We have fabricated broadband long-period gratings (LPGs) on hollow optical fibers (HOFs) by 15 corrugating slots with various widths by point-by-point exposure of a Ti:sapphire femotosecond laser. The corrugated LPGs showed unique broadband rejection whose FWHM extended to 190 nm with a low insertion loss of less than 1 dB. The maximum coupling strength was 8.5 dB, which is a significant improvement in comparison with previous HOF acousto-optic tunable filters (AOTFs). The center wavelength and coupling strength of the resonant peak could be systematically controlled by modulating the width of the corrugation.

Microstructuring of Optical Fibers Using a Femtosecond Laser

“…One-meterlong hollow optical fiber was carved by point-by-point exposure; width of 150 μm, depth of 30 μm, and period of 550 μm with 20 repeat times. The filter showed a low insertion loss of 1.7 dB and very broad FWHM of 160 nm [12]. And, we polished a photonic crystal ball lens fiber using a femtosecond laser.…”

CO2Laser Assisted Fabrication of Micro-lensed Single-mode Optical Fiber

“…Although optical fibers have been designed primarily for optical communication, they show promise in a wide range of application areas including coupling [1], fiber lasers [2], optical sensors [3][4][5][6][7][8][9], imaging and spectroscopy [10,11], and biomedical engineering [12]. In most of the cases, micro-structuring of the optical fibers is required to produce application specific optical fibers.…”

Mask-free hybrid long-period fiber grating fabrication by self-assembled periodic polymerization in silica hollow optical fiber

“…The first LPG was based on the UV photosensitivity of GeO 2 -SiO 2 core single-mode fibers (SMFs) and amplitude masks have been used under UV laser exposure to form a periodic index modulation [2]. In addition, to this UV photorefractive method, various fabrication techniques have been reported for LPGs in silica SMFs such as the use of a CO 2 laser [3,4], mechanical pressure [5,6], corrugation of cladding [7,8], and the point-to-point technique [9], to name but a few. Silica SMF-LPGs, however, have relatively low sensitivity to temperature and mechanical strain, especially when compared with polymer optical fiber (POF) LPGs [10].…”