Characterization of notched long-period fiber gratings: effects of periods, cladding thicknesses, and etching depths.

This study proposes using an inductively coupled plasma etching process to fabricate notched long-period fiber grating (NLPFG) for sensor applications. The effects of the designed parameters (i.e., different fiber cladding thicknesses, grating periods, and etching depths) are studied to explore the characterization of NLPFG. The characterization as indicated by tests of the NLPF showed that the wavelength of NLPFG produced a redshift with decreases in cladding thickness. The drift rate of the wavelength following changes in thickness was -2.801  nm/μm. In addition, a redshift also was exhibited in the increased period, with a wavelength drift rate corresponding to the size of the period of 1.466  nm/μm. Moreover, the results showed that the transmission loss in the spectra increased with etching depth. The variation rate of transmission loss based on etching depth was -0.458  dB/μm.