A dispersion flattened tellurite composite holey fiber

Abstract

Highly nonlinear tellurite holey fiber can be transparent from visible to 5 μm. Its nonlinearity can be higher than highly nonlinear silica fiber by more than one order of magnitude. However, the dispersion of tellurite holey fiber is difficult to tailor because of the difficulties in fabrication. Tellurite glass shows a low viscosity at the fiber drawing temperature. Moreover the viscosity decreases sharply with increasing temperature. Tellurite holey fiber with a complex microstructure could be subject to heavy deformation during fabrication process. So far most tellurite highly nonlinear holey fibers just have a simple structure which results in an unflattened dispersion. It cancels the advantage of high nonlinearity greatly in practical applications. In this work we try to develop a dispersion flattened tellurite composite holey fiber (TCHF). The holey structure of the TCHF is composed of only one ring of holes, so the heavy deformation, which probably occurs for tellurite complex microstructured fiber during the fabrication process, can be avoided. Since the holey structure is simple, to improve the flexibility in tailoring dispersion, we use two kinds of tellurite glasses which have different refractive-indices to design and fabricate the TCHF. The holes are formed by two tellurite glasses. The fiber can be fabricated by a simple rod-in-tube method. By using this structure the dispersion is engineered to be the most flattened for the highly nonlinear soft glass fiber within 1.5-1.6 μm. More than one octave supercontinuum generation, mainly broadened by self phase modulation, is demonstrated by using the fabricated TCHF.