Stannic oxide saturable absorbers for generating Q-switched erbium-doped fiber lasers

As a kind of transition metal oxides (TMO), stannic oxide (SnO2) has aroused extensive attention due to its direct bandgap N-type semiconductor property. However, few studies have been focused on the nonlinear property and optical modulation. Herein, passively Q-switched erbium-doped fiber lasers based on SnO2 saturable absorber (SA) are constructed and experimentally verified. To our best knowledge, this is the first report on the optical nonlinearity of SnO2 as a Q-switcher for the near-infrared fiber laser. There are two kinds of SAs fabricated by the filmy and D-shaped fiber (DF) deposition methods. A stable Q-switching operation at 1568 nm was achieved induced by the SnO2 film. After replacing SnO2 film with the SnO2-DF SA, Q-switched operations with an operating wavelength of 1532 nm was achieved. To be noted for a comparison, the performance of 1530 nm Q-switched pulses is obviously improved. Our experimental results could further promote the progress of nonlinear optic and pulsed fiber lasers.