Tapered tellurite step-index optical fiber for coherent near-to-mid-IR supercontinuum generation: experiment and modeling

摘要

We demonstrate broadband highly coherent near-to-mid-IR supercontinuum generation using a short length of tapered tellurite step-index fiber pumped with an ultrafast laser in normal dispersion regime. The tapered tellurite fiber possesses all-normal dispersion characteristics within the whole range of the generated supercontinuum spectrum. A highly coherent near-to-mid-IR supercontinuum spectrum spanning 1.28 to 3.31 mu m at a -40 dB intensity level is obtained using a 3.2 cm long tapered tellurite fiber when it is pumped with a 200 fs laser pulse with a peak power of 19.8 kW at 2 mu m. To obtain the supercontinuum spectrum, we also carried out numerical modeling for the tapered tellurite step-index fiber with the same geometrical parameters and pump conditions used in the experiment. The numerical observation supports the experimentally obtained result. The findings of this work show that the fabricated tapered tellurite step-index fiber is a promising nonlinear medium to obtain a coherent near-to-mid-IR supercontinuum spectrum in a short length of the fiber. (C) 2019 Optical Society of America