The Optical Isolator Based On Surface Plasmon Polaritons

The optical isolator is a necessary non-resource optical element in modernoptical system. An optical isolator prevents optical resource or optical elementsdamaged by reflected optics. The common optical isolator base on Faraday rotationand this is a mature technology. The size of the common optical isolator is aboutseveral centimeters. However, this is not suitable for light path integration. TheSurface Plasmon Polaritons is a hot field of Nanophotonics. It comes from theoscillation of electrons and propagates at the interface of a metal and a dielectric.SPP is a slow wave. The wavelength of it is one of ten of the excitation optics. Forthis reason, it can be used in optical elements and there are some reports about thisresearch.We have designed two modes of optical isolators which base on the theory ofSPP. The first mode makes use of the nonreciprocal coupling of waveguides. Weformulate a dielectric waveguide and a SPP waveguide which is composed by somemagneto-optical material. When at the forward direction, the light propagatessuccessfully for the mismatching of the two propagation constants. At the reversedirection, however, the light is lost because of the effective coupling of the twowaveguides.The second mode is also based on the nonreciprocal coupling of the twowaveguides, but there is a fault in the dielectric waveguide. We also formulate adielectric waveguide and a SPP waveguide while the material of the two waveguidesis not the same with the first mode. When at the forward direction, the light couplesinto the metallic waveguides. And with the SPP, the light propagates successfullythrough the fault of the mode. At the reverse direction, however, the light is not ableto couple into the metallic waveguide for the mismatching of the phase. The light isisolated for the nonexistent of the waveguide structure in the fault of the mode.