Harmonic mode-locked fiber laser based on photonic crystal fiber filled with topological insulator solution

Abstract

We reported that the photonic crystal fiber (PCF) filled with TI:Bi2Te3 nanosheets solution could act as an effective saturable absorber (SA). Employing this TI-PCF SA device; we constructed an ytterbium-doped all-fiber laser oscillator and achieved the evanescent wave mode-locking operation. Due to the large cavity dispersion; the fundamental mode-locking pulse had the large full width at half maximum (FWHM) of 2.33 ns with the repetition rate of ~1.11 MHz; and the radio frequency (RF) spectrum with signal-to-noise ratio (SNR) of 61 dB. In addition; the transition dynamics from a bunched state of pulses to harmonic mode-locking (HML) was also observed; which was up to 26th order.