Study On The Third-order Optical Nonlinearity Of Micro Nano Structure Enhanced Thin Films

Materials with third-order nonlinear optical properties play an important role in photon technology.Many porous nanomaterials exhibit excellent optical nonlinearity.Through the fabrication of porous nanostructures,the optical properties of the whole material can be enhanced or changed.In addition to optical applications,nano porous structure is becoming an ideal candidate material for chemical sensor applications.In recent years,dielectric nanoporous structures have been widely used,such as anodized aluminum,carbon nanotubes in electrochemical double-layer capacitors and metal nanowires in nonlinear optical applications.Among them,anodized aluminum template has become the preferred template for the growth of semiconductor quantum dots in photoelectric applications.In addition to the nonlinear optical properties of AAO template itself,the micro nano enhancement effect of porous alumina film on CS2 solution was studied by top hat Z-scan,and the nonlinear source was explored by finite-difference time-domain algorithm.The specific work of this paper is as follows:1)The two-step anodizing method was used to prepare the alumina template with thickness of 710 nm,pore diameter of 70 nm and cycle of 100 nm.After the two-way porous anodic alumina template is transferred to the glass substrate,the transferred sample is vertically immersed in the CS2 solution,and the preparation of the sample to be tested is completed.2)The ultra-thin porous anodic aluminum oxide film was immersed in the nonlinear solution CS2,and the structure was tested by top hat Z-scan with 532 nm nanosecond laser.The experimental results show that the samples with thin film structure do not show nonlinear absorption response under nanosecond pulse,but have strong nonlinear positive refraction enhancement effect.The third-order nonlinear index of the sample is 18 24 10AAO?m W-= × under nanosecond pulse.The electric field distribution of ultra-thin porous anodized aluminum film was analyzed by FDTD.The local enhancement of the surface is the main source of optical nonlinear enhancement.The sample has good structure enhanced optical nonlinear performance.In this paper,we have made some contributions in the field of micro nano structure enhanced third-order optical nonlinearity.The results show that the enhancement coefficient of the third-order nonlinear refractive index of CS2 solution is as high as 17.65% under 532 nm nanosecond pulse,.This study shows that the micro nano structure has good nonlinear optical enhancement performance,and has a strong potential application prospect in nonlinear optical devices.