Fiber-integrated concept to electrically tune pulsed fiber lasers based on step-chirped fiber Bragg grating arrays

We present a novel method to discretely tune the emission wavelength of pulsed fiber-integrated lasers. As spectral filter, a step-chirped fiber Bragg grating (FBG) array is employed combining a monolithic structure with an unrivaled design freedom enabling large tuning bandwidths as well as tailored spectral characteristics towards fingerprint tuning features. Together with an electrical control mechanism ensuring programmable operation, this tuning method promotes fiber-integrated lasers to access new fields of applications e.g. in biophotonics and distributed sensing. The potential of this tuning concept is investigated based on an Ytterbium-doped fiber laser. The system shows superb emission properties including excellent wavelength stability, high spectral signal contrast (up to 50dB) and narrow linewidth (15GHz) as well as adjustable pulse durations in the nanosecond range with peak powers up to 100W. Additionally, the unique spectral potential of this method is demonstrated by realizing filter designs enabling e.g. a record tuning range of 74nm for fiber-integrated lasers.