The Propagation And Control Analysis For Micro-nano Beam Waveguide

Micro-nano beam is the most promising nano-optical integrated information carrier. To control the transmission of micro-nano beam, we must first do research on the minimum size of micro-nano beam; then it will be possible to achieve the minimum size of micro-nano beam; finally a micro structure at the magnitude of sub-wavelength will be used to constitute a new structure, which may work with the function of beam shaping, widening/ narrowing the beam and wavelength selection.Slot waveguide structure is introduced in this thesis to confine the size of micro-nano beam. Taking advantage of high refractive index contrast, the beam was localized in the low refractive index slot region. Because electric field intensity in low refractive index region is much higher than in the high refractive index region, the localized beam could propagate with high electric field intensity. To improve the signal transmission characteristics of slot waveguide, photonic crystal in slot waveguide is composited in this thesis, constituting slot photonic crystal waveguide(SPCW). SPCW is expected to be able to enhances the efficiency of energy transporting, improve the signal to noise ratio, and localizes the energy in the cavity defects better, thus SPCW can be used to achieve high efficiency coupling and energy splitter.To realize the splitter structure of micro-nano beam, two kinds of splitter structure are designed which are based on coupled cavity theory and evanescent field directly coupling theory respectively. We compare characteristics such as beam splitting and the energy coupling of the two structures. Once the length of coupling slot region is beyond a certain threshold, SPCW beam splitter can achieve a extremely high efficiency of energy coupling. A new structure based on evanescent field directly coupling is designed to achieve the ability of wavelength selection. Using this structure based on SPCW, we can have two signal of the incident 1.55μm and 1.3μm communicating wavelength export though two separated output ports, achieving the purposes of two signals'wavelength selection.