Numerical Analysis Of Spectral Riaditive Properties Of Subwavelength Metallic Grating

Thermal radiation and thermal radiative spectral control are playing an important role in many applications, such as wavelength-selective thermal radiator, thermal control in space, solar collectors and laser technology. Because of scale effects, periodic micro/nano structures have some different thermal radiative properties from the macro. They are showed having great effect on the thermal radiative spectral control, however, these structures of two or three dimension are difficultly made, except for one dimension micro/nano structures. As one-dimensional periodic micro/nano structure, sub-wavelength metallic Ag grating is introduced into thermal radiation spectral control. These structures have extraordinary spectral phenomena in the visible and infrared spectral bands. The extensive research to the spectral radiative properties of sub-wavelength metallic grating may provide a useful guide to control spectrum.By using rigorous coupled wave analysis (RCWA), the two dimension finite difference time domain method (FDTD), Lorrentz-Drude dispersion model, the spectral radiation properties of sub-wavelength metallic Ag grating are numerically analyzed under different polarization. Five kinds of gratings are constructed by changing like F-P cavity's shape and position. the reflectance spectra, transmission spectra, absorption spectra and emission spectra are simulated with RCWA and FDTD with normally incident light of which wavelength is about 400nm~4000nm. The spectral properties of different gratings with variable slit cavities are depicted. Cavity mode play an important role in extraordinary spectrum properties of sub-wavelength metallic grating in the comparison between slit array grating, cylindrical array grating and cylindrical array grating based slit cavity . The simulated results exhibit that sub-wavelength metallic Ag grating with variable slit cavity structures can achieve thermal radiation spectral control by changing the slit cavity and can be used as a selective emitter in thermal photovoltaic system and wavelength-selective thermal radiator.