Ultrabroadband fiber Bragg gratings written with a highly chirped phase mask and infrared femtosecond pulses.

The writing of ultrabroadband Fiber Bragg Gratings (FBGs) is demonstrated in both hydrogen-free and hydrogen-loaded standard telecom fibers by the use of IR femtosecond pulses and a highly chirped first-order phase-mask. A high reflectivity filter providing a wavelength coverage of five telecom bands (E+S+C+L+U) is demonstrated over a single 35mm long grating inscribed in only 30s in H(2)-loaded SMF-28 fiber. Refractive index modulation of about 2.5x10(-3) and 5x10(-3) are obtained after a few second exposure time in both hydrogen-free and hydrogen-loaded SMF28 fibers. This report paves the way to the development of new broadband fiber-based optical components such as multi-wavelengths filters and sources.