All-fiber mode-locked laser utilizing 45°-tilted fiber grating based polarization beam splitter

We have experimentally demonstrated an all-fiber mode-locked laser by using a 45°-tilted fiber grating (45°-TFG) based in-fiber polarization beam splitter (PBS). Based on the nonlinear polarization rotation (NPR), the slanted refractive index modulation structure of the 45° TFG is able to tap the pluses out from the side face of the fiber. The central wavelength of the laser is 1559.9 nm and the period of pulse train is 156 ns, corresponding to the fundamental repetition rate of 6.79 MHz, the pulse energy of 0.26 nJ and the pulse duration of 1.06ps. Additionally, the laser shows a high degree of polarization (DOP) output of 99.8%. This mode-locked fiber laser with single polarization mode output is reliable during long-term operation and thus promising for many practical applications. As a proof of principle, the demonstrated laser can provide neat solution in designing compact mode-locked fiber laser.