Simultaneous multi-wavelength pulsing of passively Q-switched erbium-doped fiber laser assisted by intracavity long-period fiber grating

Abstract Intracavity wavelength-dependent loss elements in passively Q-switched fiber lasers (FL) enable adjustments to their operational regimes, first of all, the laser wavelength. Among others, long-period fiber gratings (LPFGs) are spectrally selective devices with loss-bands that can be integrated into FL cavities to modify the gain. This work demonstrates simultaneous pulsing in a passively Q-switched erbium-doped FL with a ring cavity at multiple wavelengths. A saturable absorber we used to get passive Q-switching comprises a Tm-Ho co-doped fiber and a LPFG, an intracavity spectrally selective loss element. Up to six simultaneously pulsed laser lines are achieved by deforming the LPFG to modify its loss bands spectrally. Adjusting the pump power and the LPFG’s spectral response enables repetition rates ranging from 4.17 to 16.13 kHz. This configuration demonstrates versatility and precision, thus offering new opportunities for telecommunications and advanced laser systems applications. The ability to obtain multiple spectral lines at pulsed lasing and dynamically adjust the repetition rate through LPFG tuning underscores this design’s potential for laser research and development.