Study On Radiative Properties Of One Dimensional Microscale Gratings With Rigorous Coupled-wave Analysis

As the progress in the design, fabrication and manufacture of the micro andnano technology, gratings are not only important spectral components that are widelyused in the field of optics, but also control components of radiation characteristicsthat start to be applied to solar cells, energy conversion divices and surface thermalcontrol because of good wavelength-selective characteristics.It usually gets the electromagnetic filed in space by solving the Maxwellequations, then surface radiation characteristics of micro and nano structures can beobtained. Rigorous coupled-wave analysis (RCWA) is an algorithm that isespecially suitable for solving electromagnetic field of period structures, and it hasbeen maturely adopted in the research on electromagnetic properties of gratings. Thedevelopment of RCWA is reviewed, and the theory of the algorithm is presented indetail. Moreover, RCWA is the main technology tool for radiation characteristics ofgratings in this paper.Physical mechanisms of the extraordinary absorption and transmission areascribed to surface plamon polarizations (SPP), surface phonon polarizations (SPhP)and local magnetic polarizations (MP) recently. In the paper the reason why gratingsare wavelength-selective is explained with numerical results of RCWA. Theequivalent capacitance and inductance (LC) circuit model is analysed and modified,which is used to forecaste the peak of absorption of gratings. The influence of thedispersion relationship of penetration depth on LC circuit model are took intoaccount, as well as the distribution coefficient of electric charge. Besides, the LCmodel extends to the predication for peaks of MPn (n>1).Gratings in micro and nano scale are generally adhered to a film base. However,in the process of fabrication and fixing the film base may corrugate periodically, andthe effect of the corrugation in Si gratings is analysed and considered by multilayermodel approximation. It finds that different types of curves show varying patterns.The film corrugate at an angle can be one of fine adjustments toward radiationcharacteristics of Si gratings.Finally, the model of Morpho wing structures is proposed by the multilayergrating model, and the influence of parameters in the model on structural colors isestimated. It shows that vertical parameters affect radiation characteristics muchmore than horizontal parameters, and on the other hand it comfirms the validity of the simple multilayer model and photonic crystal model adopted in the study ofmorpho wing structural colors. The morpho wing color changes when the directionof light or the ambient refractive index alters, and results comes from numericalsimulation of grating model that imitates the structure of morpho wing exactlyexplain phenomena.