Effects of boron in <inline-formula><math altimg="none" display="inline" overflow="scroll"><mrow><mi>Ge</mi><mtext>-</mtext><mi mathvariant="normal">B</mi></mrow></math></inline-formula> co-doped fiber on the spectral characteristics of optical fiber gratings

Abstract

We investigate the effects of co-doping of boron on the index difference between the core and cladding of the optical fiber, the temperature and bending sensitivities of a long-period fiber grating (LPFG), and the resonance wavelength separation between the core mode and the first cladding mode of a fiber Bragg grating (FBG). We observe that the index difference between the core and cladding decreases with the slope of 1.69×10−4/SCCM and that the temperature sensitivity of the resonance wavelength shift of LPFG decreased with the slope of 0.01145 nm/°C/SCCM. The measurement results indicate that, as the amount of the co-doped boron is increased, the bending sensitivity of LPFGs increases, while the resonance wavelength separation between the core mode and the first cladding mode of FBGs decreases. These results may be used for design of Ge-B co-doped optical fibers with the desired characteristics suitable for optical fiber communication and sensing applications.