Simulation Of Radiation And Polarization Characteristics Of Porous Microstructure And Rough Surfaces

When the incident wavelength is close to the geometrical scale of micro-structure, the microscale effect is generate. The radiative and polarization characteristics of the micro-structure should be obtained by the Maxwell equations. In the past few years, the study mainly focused on the preparation method and energy transmission. This thesis investigated a metal porous microstructure and a random rough surface. The first part is the radiative and polarization characteristics of a metal porous microstructure, the second part is correction effect of the effective roughness layer model in ellipsometric experiments.In this work, the finite-difference time-domain(FDTD) method for electromagnetics was used to calculate the spectral radiative properties of the metal porous microstructure. It is found that, when the pore diameter is range of 0.2~0.8μm, the absorption spectra of the nickel porous microstructure will generate two peaks within the wavelength range of 0.2~2.0μm at normal incidence of light. Furthermore, the value, position and shape of the absorption peaks have tightly coupled relationships with the pore diameter, the filling height of nickel, the incident angle and polarization of light. Besides, the effect of temperature on the tungsten porous microstructure was also studied. Additionally, it is revealed that the power absorption predominantly focuses on the top surface of the structure, especially on the region near the orifice. In practical application, we can enhance the efficiency of power absorption in the target wavelength by modulating the pore size, the filling height of nickel, the incident angle and polarizati on of light, which has great potential in many fields such as thermophotovoltaic(TPV) systems and impact energy absorption applications. Besides, the effect of the pore diameter on the polarization characteristics of the nickel porous microstructure was also studied.The effective roughness layer(ERL) model is used for optical constant correction in ellipsometric experiments. In this paper, t he FDTD method for electromagnetics and the effective roughness layer model for effective medium approximation were used to calculate the ellipsometry parameters of a random rough surface, take the results of FDTD method as standard, compared the two groups of data, analysised the correction effect of the effective roughness layer model in ellipsometric experiments. The results show that, the bigger the root-mean-square(RMS) roughness is, the lower the accuracy of the ERL model becomes, and the smaller the incident wavelength is, this trend is more obvious. When the incident angle is close to the Brewster angle, the accuracy of the ERL model will decrease, and the smaller the value of optical constant k is, this trend is more obvious. In addition, the autocorrelation length also have influence on the accuracy of the ERL model, the results show that, when the autocorrelation length is 0.5?m, the accuracy of the ERL model is the highest. This work can provide an error range of the ERL model in ellipsometric experiments using this model for optical constant correction in future.