Study On Supencontinuum Sources Based On Tellurite Microstructured Fibers

All fiber based broadband supercontinuum light source can be usedin fundamentally cutting-edge research, optical communication,environmental monitoring, medical and even defense. Especially, indefense and security, the supercontinuum lasers can serve as ideal lightsources for infrared countermeasure due to its wide spectral bandwidth,high brightness and spatial coherence,. The realization of the broadbandsupercontinuum laser is thereby typically at a premium for both academiaand industry. Silica microstructure fiber based supercontinuum lightsource with limited wavelength range covering0.32m has beenalmost technique-mature and commercially available now. It is critical toextend the long wavelength range of the source to mid-infraredwavelength range, especially longer than2m, for real applications.The narrow transparency window of silica fiber (0.32.5m)restricts the applications in the mid-infrared spectral range itself. Thelonger wavelengths can be continued in the case of telluride、fluoride andchalcogenide fiber-based supercontinuum sources. Among them, telluridefiber is expected to yield all fiber compact and portable mid-infraredsupercontinuum sources because of the combination of high nonlinearity,thermal stability and chemical resistance properties. Despite recentprogress in this field, the systematic investigation on the supercontinuum reported. During my master study, I am focused on the systematicallyinvestigation on the supercontinuum spectrum generation in telluridemicrostructure fibers and the results are given as follows.The simulation work consists of three parts. First of all, wenumerically demonstrated the dependency of the chromatic dispersion,nonlinearity and effective mode area on the fiber structure. The resultsshow that the size of fiber core and the surrounding air holes plays a vitalrole on the fiber parameters. In detail, the nonlinearity coefficients andthe effective area of the fiber varies nonlinearly with the size of the coreand the air holes. Secondly, we modeled the pulse propagation processesand systematically studied the supercontinuum generation in telluridemicrostructure fibers by solving the numerical model with a split-stepFourier method. Note that, we incorporate the influence of the parameters,like fiber geometry、length、dispersion、pulse duration and also the peakpower of the pump into the the model and simulated the dependency ofthe peak power, pulse duration of the pump and core diameter on theproperties of the supercontinuum spectrum. The simulated results showthat the optimal core diameter is3.5μm for the generation of broadbandsupercontinuum spectrum when pumped with a1560nm femtosecondmode-locked laser. Thirdly, we investigated the broadband tunableoptical parametric process in telluride microstructure fibers numerically. By using a1560nm laser as the pump source, an optical parametricsource with a tunable wavelength range covering2065-2925nm wasobtained; In comparison, an optical parametric source with a tunablewavelength range from3540nm to4185nm was achieved when pumpedat2m.We experimentally investigated the influence of peak power, fiberlength, core diameter on the generation of supercontinuum source whenpumped by a1560nm femtosecond mode-locked laser in telluridemicrostructure fibers, which were fabricated via a rod-in-tube approach.Through careful optimization of the paremeters we studied, ansupercontinuum spectrum covering the wavelength range of1017-2300nm was obtained in a3cm telluride microstructure fiber for apump pulse width of1.2ps and an average power of725mW.