Dispersion mitigation using cascaded FBGs with hybrid apodization profiles

Abstract

Abstract The performance of high-speed optical communication systems is constrained by Chromatic Dispersion (CD), which poses a significant challenge to data transmission integrity. This paper proposes a method to mitigate CD using cascaded Apodized Fiber Bragg Gratings (AFBGs). The apodization function plays a crucial role in dispersion mitigation, effectively reducing side lobes in the Fiber Bragg Grating (FBG) reflection spectrum. The proposed model employs two cascaded stages, each utilizing an apodization function that merges the Nuttall and Bartlett profiles. This model is investigated to enhance FBG performance and is compared with other apodization functions. Using an induced refractive index of 2.8 × 10⁻⁵ and a grating length of 60 mm, numerical results show that the Nuttall-Bartlett apodization function achieves the narrowest Full Width at Half Maximum (FWHM) of 0.027 nm—a 20.48% improvement over the uniform model—while maintaining a reflectivity of 99.12%. The performance of the proposed model is further evaluated through the quality factor (Q-factor) and Bit Error Rate (BER), yielding an improvement in both metrics over the uniform model.