In summary, an ultrabroadband SC spanning from 1.5 μm to 14.3 μm with a high coherent property is obtained in a 10 cm long ANDi T-DCF pumped at 6 μm. For comparison, the SC broadening in an ANDi T-SIF under the same pumping conditions is also measured. Our results show that double clad leads not only to improve the mechanical strength but also lower the energy loss in the transition region of the fiber taper for ultra-broadband SC generation, which has a considerable practical potential in various applications.