Fabrication And Supercontinuum Spectrum Generation Of As₂S₃ And As₄₀Se₄₀Te₂₀ Fibers

Chalcogenide glass has characteristics of high refractive,non-linear refractive index,low phonon energy,excellent infrared transmission performance,unique photosensitivity,and various photoinduced effects.Therefore,it has great potential applications in many fields,such as medical detection,spatial nulling interferometer,and mid-infrared sensing.In addition,due to the high nonlinearity and the mid-far infrared transmission performance of the chalcogenide glasses,the chalcogenide fiber becomes the best medium for generating the supercontinuum spectrum.At present,the loss of optical fiber is still the biggest factor restricting the further development of the chalcogenide fiber.Therefore,how to reduce the impurity content to reduce fiber loss by improving the purification process has been one of the research hotspots of chalcogenide glasses and fibers.According to the existing preparation and purification process of chalcogenide glasses,As₂S₃ glass with good stability and mature preparation process,and As₄₀Se₄₀Te₂₀ glass with wide mid-infrared transmission and weak crystallization were selected as the main research objects.The preparation processes of two low-loss chalcogenide fibers were studied and developed for glass components.The influence of pump wavelength and pump power on the output characteristics of SC spectrum was studied by pumping with optical parametric amplifier（OPA）.The research contents and results are as follows:（1）The effects of parameters such as glass melting temperature,rest time and annealing temperature on the formation of chalcogenide glasses were investigated.The purification process of multiple dynamic distillation,whole distillation,addition of oxygen scavenger,addition of hydrogen removal agent,were studied.Finally,a high purity chalcogenide glass preparation technology combining various purification processes was explored.（2）The isolation extrusion technology and fiber drawing technology for preparing step-index As-S and As-Se-Te fibers were studied,The As₂S₃ fiber with core-cladding ratio 1:25 and the As₄₀Se₄₀Te₂₀ fiber with core-cladding ratio 1:5 were prepared.The minimum loss of As₂S₃ fiber is 1.76 d B/m.The minimum loss of As₄₀Se₄₀Te₂₀ unclad and step-index fiber is 1.70 d B/m and 5.65 d B/m,respectively.（3）A widest supercontinuum spectrum covering 1.4⁸.5 μm is obtained by pumping As₂S₃ fiber with different pump powers and wavelengths in the anomalous dispersion region.The analysis found that at low power,the broadening of the SC spectrum increases with the pump power,but there is an optimal pump power.The pump wavelength,which is in the anomalous dispersion region and close to the zero dispersion wavelength（ZDW）,is easier to obtain a wider SC spectrum.（4）The supercontinuum with the widest coverage of 1.8¹3 μm is obtained by pumping As₄₀Se₄₀Te₂₀ fiber with different pump powers and wavelengths in the normal dispersion region.The experimental results show that a shorter pump wavelength can produce a wider SC spectrum in the normal dispersion region away from ZDW（9.4 μm）.The mid-infrared supercontinuum regeneration spectrum of chalcogenide glass fibers,especially the ultra-wideband output spectrum covering 2¹3 μm,is expected to be developed into a new generation of mid-infrared broadband source,which has important applications in mid-infrared gas sensing,laser medical,femtosecond photon microscopic imaging,laser processing,and other fields.