Cascaded telecom fiber enabled high-order random fiber laser beyond zero-dispersion wavelength

Four-wave mixing induced spectral broadening near the zero-dispersion wavelength (ZDW) of the fiber is a bottleneck factor that limits the further wavelength extending in cascaded random fiber lasers (RFLs). In this Letter, we successfully suppress the spectral broadening near the ZDW of the fiber in the cascaded RFL by simply combining two kinds of commercial telecom fibers with different ZDWs, G655C fiber with ZDW around 1.52 µm and G652D fiber with ZDW around 1.31 µm. As a result, an 8th order Stokes light component at 1721 nm with a maximum output power of 2.1 W and a spectral purity of 96.94% is realized in this telecom-fiber-based cascaded RFL. This work provides a reference of nonlinear effect management in fiber lasers as well as affords a cost-effective way with great potential of realizing high-power widely tunable fiber lasers.