Carbon nanoparticles (CNPs) as a saturable absorber for a passively Q-switched erbium (Er3+) doped fiber laser

Abstract

The carbon nanoparticles (CNPs) are demonstrated to be capable of acting as a saturable absorber (SA) for the Q-switching of an erbium doped fiber laser (EDFL). The Q-switched EDFL based on CNPs-SA emits at a central wavelength of 1566 nm with a 3 dB spectral bandwidth of 1.72 nm. The radio-frequency (RF) spectrum has a signal-to-noise ratio (SNR) of 42 dB at the fundamental repetiton rate, indicating a good pulse stability. The stable pulse operation can be maintained under the pump power of ranging from 28 to 272 mW. The pulse repetition frequency increases from 12.26 to 73.30 kHz, and the pulse narrows down from 23.32 to 6.27 μs, correspondingly. In addition, we investigate the nonlinear saturable absorption property of CNPs, and measure the SA’s damange threshold as well as the modulation depth. The synthesized CNPs are also characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Energy dispersive X-rays (EDX), Raman, Photoluminescence (PL), X-rays diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy. These experimental results reveal that CNPs-based SAs can be equivalent or even superior to the widely used nanoparticle SAs, and will have potential applications for pulsed laser sources.