Nonlinearly chirped fiber Bragg gratings by selective refractive index tuning using femtosecond laser pulses (Conference Presentation)

We present a novel approach for the inscription of nonlinearly chirped fiber Bragg gratings (N-CFBGs) using femtosecond laser pulses. This approach allows the efficient fabrication of N-CFBGs by partially tuning the average refractive index of an already inscribed linearly CFBG. No complex phase mask designs or further modifications of the inscription setup are necessary. This approach involves selectively modifying the average refractive index perturbation and the index offset of smaller sections of the grating and has the advantage of reproducibility and flexibility. It paves the way for N-CFBGs with tailored dispersion profiles used in fiber based CPA systems.