Polarization Characteristics And Fabrication Process Of The Sub-wavelength Metal Grating

Subwavelength metallic grating has special diffraction field as its period is shorter than working wavelength. It has received great deal of interests from researchers. To the grating, the TM mode is highly transmitted and the TE mode is reflected, so its polarization properties is excellent. And also, it has been widely used in varieties of fields for its advantages of small size, wide spectrum and high integration which don't belong to the traditional grating devices.This paper has researched the metallic grating polarizer which is used in the polarized camera. It focuses on what influence the structure parameters have to the polarization properties and the fabrication process of the one dimensional subwavelength metallic grating. The work has provided the basis of theoretical and experimental for the later practical uses. The main content of the paper include:First of all, the structure of the grating was optimized. Two numerical methods based on the solutions of the Maxwell equations for the metallic grating structure were introduced: finite difference time domain method(FDTD)and rigorous coupled-wave method(RCWA). Then by using of the software Rsoft which is based on the methods above,the re lationship between the structure parameters and the polarization properties was simulated and the optimized parameters were obtained.Next, the basic fabrication process was studied with experiments. A new silicon layer was put forwarded as the second mask.Also, the difficulties that it is hard to remove the remains of etching and the photoresist is easily broken were improved. Thus, the SEM image of the sample profile proved that the depth of the etched groove was finally developed.Finally, a new structure of double metallic layer was developed to avoid the etching process.The polarization property of the double structure is better than that of the single structure's in the simulation consequence. And also, the fabrication process of this structure was completed and the sample was tested by the ellipsometer.The difference between the results got from the simulation and the experience was analyzed at last.