Compact Passive Q-Switching Pr3+-Doped ZBLAN Fiber Laser With Black Phosphorus-Based Saturable Absorber

In this paper, a compact passively Q-switched praseodymium (Pr
³⁺
)-doped fiber laser at the wavelength of 635 nm with black phosphorus (BP) saturable absorber (SA) was first investigated. BP nanoflakes were manufactured by the liquid-phase-exfoliation method and then embedded into polyvinyl-alcohol (PVA) film for the experimental usage and a fiber pigtail mirror (FPM, by coating dielectric film onto the fiber-end face) was applied to realize a compact Pr
³⁺
-doped red fiber laser. By transferring a block of the BP-PVA thin film onto the FPM and then incorporating into the compact Pr
³⁺
-doped fiber laser, the Q-switched operation at 635 nm was achieved. The pulse-repetition rate of the visible-wavelength Q-switched fiber laser can be widely tuned from 108.8 to 409.8 kHz and the shortest pulse duration of this laser is 383 ns. These results reveal that the BP is an available SA for red-light lasers.