Spectral responses of tilted fiber Bragg grating coated with a thin Ge2Sb2Se4Te1 layer

This article reports the spectral properties of a Ge2Sb2Se4Te1 (GSST) -coated tilted fiber Bragg grating to the changes of surrounding refractive index (SRI). The variations of the cladding mode resonance amplitudes and wavelengths under two orthogonal polarization modes are analyzed and validated with the simulation results. The introduction of the high index coating has induced non-degeneracy to the cladding modes, but the effect gradually diminishes with increasing SRI. The SRI sensitivities of the s-polarized modes have been substantially suppressed and became 20 times lower than that of p-polarized modes. The findings also reveal the association between the cladding resonance amplitudes, the imaginary part of the effective refractive indices and the evanescent field intensity distributions.

Automated summary

This article presents the spectral properties of a Ge2Sb2Se4Te1 (GSST)-coated tilted fiber Bragg grating in response to changes in the surrounding refractive index (SRI). The variations of cladding mode resonance amplitudes and wavelengths under two orthogonal polarization modes are analyzed and validated with simulation results. The introduction of a high index coating induces non-degeneracy in the cladding modes, which gradually diminishes as SRI increases. The SRI sensitivities of s-polarized modes are substantially reduced and become 20 times lower than p-polarized modes. The findings also establish the relationship between cladding resonance amplitudes, the imaginary part of effective refractive indices, and evanescent field intensity distributions.