Dispersion-engineered Fluorotellurite Microstructured Fibers And Their Application In Supercontinuum Generation

Tellurite fibers with high nonlinear refractive index,stable chemical and thermal properties,high damage threshold were widely used in numerous fields such as broadband amplifier,fiber lasers,optical information processing,supercontinuum light sources.In order to broaden the transmission window of the fiber materials,our team explored the fluorotellurite glass made of TeO2-BaF2-Y2O3,which had high transmittance in the spectral range of 0.4~6 ?m.By optimizing the fiber fabrication technology to avoid the crystallization during fiber drawing,we fabricated Ho3+-doped fluorotellurite microstructured fibers and obtained high-efficiency lasing at 2 ?m from such microstructured fibers.In addition,the early results showed that fluorotellurite fibers were promising candidates for generating broadband supercontinuum light.During the doctoral years,the author has worked on the design,fabrication of the dispersion-engineered fluorotellurite microstructured fibers and obtaining the broadband supercontinuum light sources from the fibers.The author achieved a series of research results as follows:(1)The air cladding fluorotellurite microstructured fibers were designed and fabricated.By controlling the relative size between the air hole and fiber core,the dispersion of the fluorotellurite microstructured fibers could be engineered in a large scale.We further designed and fabricated the dispersion-decreasing fluorotellurite microstructured fibers,whose zero-dispersion wavelengths moved from 1735 nm to845 nm.(2)The effect of horizontal and longitudinal dispersion-engineered fluorotellurite microstructured fibers on the nonlinear effects was studied.We found that addition of longitudinal engineering dispersion could realize phase matched conditions in a broadband range,which did good to obtain the supercontinuum light sources with broader bandwidth.Experimentally,by using a fluorotellurite microstructured fiber with the aperture ratio ~0.8,the core diameter ~6 ?m as the nonlinear medium and a1560 nm femtosecond fiber laser as the pump source,broadband supercontinuum generation covering from 620 to 2770 nm was obtained.By using a fluorotellurite microstructured fiber with the aperture ratio ~2.5,the core diameter ~4 ?m as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source,broadband supercontinuum generation covering from 437 to 2850 nm was obtained.In addition,we also observed a blue-shifted dispersive wave at ~489 nm from the fiber.(3)Breathing behavior of the high-order soliton and third harmonic was observed in the dispersion-decreasing fluorotellurite microstructured fiber.Experimentally,by using a fluorotellurite microstructured fiber with the aperture ratio~3,the core diameter ~3 ?m as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source,drastic breathing behavior of the high-order soliton was observed by measuring the dependence of the output spectrum on the pump power of the 1560 nm femtosecond fiber laser.To further verify the effects of breathing behavior of higher-order solitons on dispersive waves and third harmonic,we found that dispersive waves generated by breathing solitons did not breathe and the third harmonic presenten obvious breathing behavior.