All-fiber passively Q-switched erbium-doped laser with Cr2+:ZnSe nanocrystals saturable absorber

Abstract

We experimentally demonstrate an all-fiber Q-switched erbium-doped laser using polyvinyl alcohol-based Cr2+:ZnSe nanocrystals (NCs) as saturable absorbers (SAs). The Cr2+:ZnSe NCs were produced by femtosecond laser ablation, and were spherical, with an average radius of about 107 nm. The nonlinear saturable absorption was characterized with a saturable optical intensity of 20 MW cm−2 and a modulation depth of ∼24%. By placing the SA inside an erbium-doped fiber (EDF) laser cavity, a stable 3.152 μs pulse with a repetition rate of 34.452 kHz centered at 1564 nm was achieved, when pumped at the maximum pumping power of 300 mW. The maximum pulse energy reached 33 nJ and the signal-to-noise ratio was 48 dB. The results indicate that Cr2±:ZnSe NCs are promising for the development of a stable all-fiber passively Q-switched EDF laser.