A new microstructured optical fiber with composite square air-hole lattice is presented
the cladding of which is composed of air holes of different sizes.The effects of the changes of its geometric structural parameters on the dispersion curves of the fundamental mode are analyzed by using the Finite-Difference Time-Domain(FDTD)method.The results show that with two sets of air holes
this microstructured fiber has strong dispersion control capability and relatively lower and more flattened dispersion curves by optimization.