Spectral Characteristics of Cascaded FBGs with Hyperbolic Tangent Apodization

Herein, a cascaded arrangement of apodized fiber Bragg gratings or FBGs of different lengths works in the C-band is presented. Each FBG in the proposed arrangement is apodized with a hyperbolic tangent function. Through the use of MATLAB, the presented structure is simulated and examined. Such a cascaded arrangement can be utilized as narrow-band filter for communication or as a passive optic device to improve the performance of the optical link. As per the simulation results, the introduced arrangement attains the highest reflectivity of 70.82% corresponding to a full width at half maximum (FWHM) of 0.09 nm. Further, an enhanced FWHM at the expense of reflectivity is presented.