The Coupling Effect And Their Design Of Novel Surface Plasmon Waveguides

In this paper, we proposed the new features of surface plasmon polaritons (SPPs) and SPP waveguide, e.g. beyond diffraction limit, contra-directional coupling and interference. By using these new features, several new devices with novel geometry were designed for Integrated optical circuits. In present paper, a novel composite metal-dielectric-metal (MDM) surface plasmon polariton (SPP) structures are first proposed to realize the ultra-short optical splitters with simplified designs. The operation mechanism is based on the contra-directional coupling and reference achieved in composite plasmonic slot waveguides. In certain cases, the switching function can also be realized. It is further shown that based on the same physical mechanism multi-dielectric-core composite MDM structures could serve as a novel plasmonic waveguide crossover component with low cross talk and high throughput. At last, we display a novel wavelength selector which also is important instrumental components used to obtain a certain wavelength or a narrow band of wavelengths. The main contents are described as follow:1. We performed the new features of SPPs waveguide and the calculation of dispersion curve on different waveguide geometry. Over the past years, various plasmonic waveguide structures such as metallic stripes, metal-dielectric-metal (MDM) and dielectric-metal-dielectric (DMD) structures, dielectric-loaded SPP waveguides, V-shaped metal grooves, and A-shaped metal wedges have been proposed as interconnects for information transport. Especially MDM and DMD structures are chosen to realize our design for the simple geometry.2. Under the incidence of TM plane wave. we introduced the composite MDM surface plasmon polariton structures for the ultra-short optical splitters. The contra-directional coupling between two adjacent MDM waveguides with different dielectric core but operating in the same wavelength range is first discussed. Attention that MDM waveguides have two dispersion curve. The lower branch always represents positive effective refraction and the upper branch represents negative effective refraction. Within the frequencies we interest, a silver-Si3N4-silver SPP waveguides with positive effective refraction and a silver-GaP-silver SPP waveguides with negative effective refraction were chosen. When we put these two MDM waveguides together, the contra-directional coupling occur and the input power flow into the adjacent waveguide with a opposite propagation direction. Then, we propose a composite MDM structure composed of a silver-GaP-silver structure sandwiched between two silver-Si3N4-silver SPP waveguides to realize the ultra-short plasmonic splitters at visible frequencies. In certain cases, the switching function can also be achieved. Furthermore, based on the same physical mechanism, a novel plasmonic waveguide crossover component with low cross talk and high throughput is designed and calculated.3. When the contra-directional coupling occurs, the incident light cannot propagation in the composite waveguide and these total refection means a photonic band gap appears in this structure. These band gap is similar with the conventional Bragg structure. Now we introduced the contra-directional coupling in certain section of waveguide propagation to realize a novel wavelength selector. Bragg reflector have been used in the design of integrated optical devices and indeed observed the wavelength select. However, by using the the contra-directional coupling in the MDM surface plasmon polariton structures, a wavelength selector with simple two-slit model also can well complete. Furthermore, in the Bragg reflector,-7 periods are needed to ensure the total refraction. In the contra-directional coupling structure, certain composite waveguide coupling length are also needed to ensure the total refraction. The wavelength select function and our simulations confirm the results.