| With the advent of the information era, the information capacity need to be processing is constantly increasing, how to be more rapid processing huge amounts of information is particularly important. The modern information processing technology is using the integrated circuit as the carrier, and its speed depends on the integration of electronic circuits. However, the further integration chip will cause the inevitable quantum effect, leading the further information processing technology development to encounter bottleneck. Therefore, using integrated optical chip to replace integrated electronic chip as the carrier of information expected to further solve the problem of information high-speed transmission. However, the integrated optical circuit is limited by the diffraction limit, the degree of integration is confined to the light wavelength scale, even can’t reach as high as electronic circuit miniaturization.Metamaterials, namely artificial composite metal subwavelength structure, it can realize all kinds of exotic electromagnetic phenomenon by stimulating surface plasmon, such as extraordinary optical transmission, negative refraction and perfect absorption. The photonic devices based on metamaterials have the ability to modulate and transmit information by employing the surface plasmon wave. Its ability of flexible modulating and transmitting electromagnetic waves in the subwavelength scale, making the photonic devices based on metamaterials expected to break the diffraction limit. It makes the device possess the advantage of compact structure and high integration which supply opportunity of making photonic chips which is connecting to exiting electric chips. It is very important for solving the quantum effect caused by chip miniaturization.In this thesis, by utilizing the finite time domain difference method of the electromagnetic simulation, we designed two kinds of compound metal artificial micro-structure, which can realize the perfect absorption. On the basis of meeting the perfect absorption, two kinds of reflective dual-band polarization filter have been designed. The specific research results and works are as follows:1. The dual-band tunable polarization filter based on a side-by-side double asymmetric cross composite metal structure has been designed and analyzed. According to the result, different dual-band resonant wavelengths are filtered while the incident light has different polarizations. Further analysis shows that: The resonant absorption wavelength of the filter depends on the length of the metal strip which parallel to polarization direction, and independent of the length of the metal strip which vertical to polarization direction. Therefore, the filter wavelengths can be tuned freely by adjusting the length of the corresponding metal strip. In addition, the calculated results show that the reflectivity of four filter wavelength of two polarization direction are closed to zero, which implies that the filter exhibits good filtering performance.2. The dual-band tunable polarization filter based on a nested double asymmetric cross composite metal structure has been designed and analyzed. Because absorption wavelength only depends on the metal strip which parallel to incident light polarization. Therefore, by putting a different size of the periodic array of asymmetric cross metal structure nest in the periodic array of asymmetric cross metal structure, a new dual-band tunable polarization filter can be designed. According to the result, different dual-band resonant wavelengths are filtered while the incident light has different polarizations, and the filter wavelengths can also be tuned freely by adjusting the length of the corresponding metal strip. Because it is a nested structure, the device can be more compact and smaller.Highlights of the thesis are as following:Based on the perfect absorption properties of surface plasmon metamaterials, two different structures of dual-band tunable polarization filter are proposed designed. The two different resonant wavelength absorption can be realized in the Ex and Ey direction. These two kinds of dual-band tunable polarization filter have compact size, working wavelength tunable, simple manufacturing process, thus can be used in the future of the integrated optical chip. |
PDF Full Text Request