Tellurite composite microstructured optical fibers with ultra-flattened and zero dispersion

Abstract

We report the fabrication of tellurite composite microstructured optical fiber (CMOF) with ultra-flattened zero dispersion (±3 ps/nm/Km) over 200nm band. To obtain this dispersion profile together with high nonlinearity, one ring of air holes and two layers of glass cladding are employed in the tellurite CMOF. The core of fiber is made of TeO 2 -Li 2 O-WO 3 -MoO 3 -Nb 2 O 5 (TLWMN) tellurite glass which possesses high linear and nonlinear refractive indices. The refractive index (n) at 1544nm and nonlinear refractive index (n2) of TLWMN glass is 2.08 and 3.78×10 -11 esu, respectively. TeO 2 -ZnO-Na 2 O-La 2 O 3 (TZNL) glass with n of 1.96 at 1544 nm and TeO 2 -ZnO-Li 2 O-Na 2 O-P 2 O 5 (TZLNP) glass with low refractive index n of 1.63 at 1544 nm are used as the first cladding and the second cladding, respectively. Six small air holes are located between the core and the first glass cladding. Such kind of fiber with ~1.7 μm core and ~0.6 μm air holes are fabricated by a rod-in-tube method. The chromatic dispersion of the fiber is calculated by the fully vectorial finite difference method (FV-FDM) and becomes (±3 ps/nm/Km) in the wide range from 1.53 μm to 1.72 μm. And the nonlinear coefficient of present fiber is about 3.47 m -1 W -1 which is much higher than that of silica MOFs. Furthermore, broad and flattened supercontinuum generation is demonstrated in 30-cm-long fiber with femtosecond laser pumping at 1557 nm. This kind of fiber has promising potential in nonlinear applications owing to the high nonlinearity and flattened dispersion profile.