Infrared Radiative Properties Of Micro Scale Structures Of Near-surface

Traditional thermal radiative heat transfer theory is based mainly on the geometric optics assumptions. It does not consider the wave effect of radiative transfer in the near-surface of microstructures. Thus, it has high computational efficiency and accuracy in the calculation of macro-scale thermal radiative transfer. However, the wave effect of the radiative transfer in the near-surface microstructures can not be ignored, and traditional geometrical optics is no longer applicable to the calculation of the effect of microscale heat transfer, when the parameter scale of the structures is gradually close to the thermal incident wavelength.Rigorous electromagnetic field numerical methods, which are built on the basis of Maxwell equations, can accurately simulate the propagation of electromagnetic field and the microscale radiative transfer effects. However, it takes a relatively large computer memory and more computing time.In this paper, rigorous electromagnetic numerical methods, such as finite-difference time-domain (FDTD) and rigorous coupled-wave analysis (RCWA), are used to calculate the micro scale radiative heat transfer. A hybrid partial coherence and geometry optics (HPCGO) method is developed, considering the wave effect. The measurement devices of microscale heat radiative properties are introduced. The measured results are compared and analyzed with the numerical results. The main work includes the following four aspects:1. The bidirectional reflectance distribution function (BRDF) of random rough aluminum surfaces is studied. The influences of the oxide films and water films contamination are also considered. Considering coherence caused by oxide films to improve the traditional geometric optics approximation (GOA) method and develop the HPCGO method. The radiative properties of one-dimensional random rough silicon surfaces coated with oxide films are studied by the HPCGO method. It is compared with the FDTD method to find out the percentage error and the applicable region.2. The infrared radiative properties of metal gratings, especially their unique resonance properties are studied in detail in order to achieve an effective method for controlling the infrared radiative properties of gratings. The radiative properties of non-metallic and composite gratings are studied to identify the cavity resonance modes with different resonance wavelengths. Devices for measuring microscale heat radiative properties are introduced. Sine-structure aluminum grating samples are measured in microscale. Moreover, the measured results are compared and analyzed with the numerical results.3. The impact of the oxide film on the radiative properties of two different grating structures (rectangular grating and sawtooth grating) is calculated. The influence of slight geometry modification, generated by fabrication errors, on radiative properties of the triangular grating is mainly investigated. An optical vortex is found due to the coupling of the surface waves, the oblique incident wave and the scattering waves.4. We develop an alternative approach to selective wavelength of light absorption (both TE and TM waves), based on an optical board periodical embedded with optical black holes. It is very useful to develop a novel geometry for wavelength-selective light absorption without the limitation of the incidence light’s polarization state. We further discuss the infrared radiative properties of the elliptical optical black hole with the GOA method and the FDTD method. A square optical black hole (SOBH) is used instead of a circular one. A critical wavelength of diffraction effects is found. Finally, eleven different materials for insulators and semiconductors are selected. The infrared radiative properties of the square cylindrical optical black hole of these materials are studied. The effects of the number of different types of materials and the structure sizes on the infrared radiative properties are summarized.