Research On Numerical Z-scan Experiments Based On FDTD

Nonlinear optical materials is the physical basis to design and exploitmost optoelectronic devices. Doped the nonlinear optical materials intothe dielectric periodically, the nonlinear optical parameters of theconventional nonlinear materials can be regulated if the structure beappropriately designed, So it provide a new degree of freedom fordesigning optoelectronic components based on nonlinear effects.Therefore, how to accurately predict the effective nonlinear opticalparameters of the microphotonic materials become the primary problem todesign new optoelectronic devices based on microstructure. This articlemainly focus on the effective third-order nonlinear effect, and establisheda numerical Z-scans measured methods based on the finite-differencetime-domain. Studied the effective third-order nonlinear refractive indexcoefficient of the microstructured materials with Kerr media, and obtainedsome achievement, specifically summarized as follows.(1)Contrasted and analysed the currently existed measurement method to measure the nonlinear optical coefficient of the nonlinearmedium such as degenerate four-wave mixing method, the pump laserdetection method, nonlinear interferometry, ellipsometry, measurement ofthe beam distortion and optical Kerr effect method etc, and their principleof measuring the nonlinear optical coefficient of the material, summarizedtheir scope of aplication, advantages and disadvantages respectively.(2)Contrast to Z-scan experiment, according to the characteristics ofthe numerical simulation, established a numerical Z-scans measuredmethods based on the finite-difference time-domain, made CS2microstructured dielectric plate as a sample, extracted its third-ordernonlinear refractive index coefficient combined with theory describedpreviously. The results showed that almost completely consistent with thetheoretical value, the error rate can be controlled in less than3%. Andmade a detailed analysis on the main parameters which affect the accuracyof the third-order nonlinear refractive index of the CS2, such as theintensity and waist radius of the Gaussian beam, the thickness of thesample, the size of the hole of the recorder, summarized the note on the application of the numerical Z-scan method.