Efficient Waveguide Coupling of 1D Photonic Crystal Surface Plasmon Coupling Cavity

The emerging surface plasmon technology could break through the diffraction limit by the miniaturization of the laser. However, the efficient coupling from the plasmon lasers to waveguides is still a fundamental and practical challenge. In the paper, a novel surface plasmon square cavity with tapered one-dimensional photonic crystal (1D PhC) structure coupling to a waveguide is designed. We simulate and optimize the PhC plasmon coupling cavity structure parameters. The waveguide coupling efficiency of similar to 77% is achieved. The simulated results show that the quality factor is similar to 385 for this double-cavity coupling scheme at a operating wavelength of 1561nm. The coupling cavity width is only about lambda/3. It is nearly lossless for the light propagating in the coupled Si waveguide. Moreover, the tapered PhC coupling cavity can be served as an ultra-small emitter source with an output power of 50 mu W at the input current of 100 mu A, which is similar to 7 times more than that of the straight waveguide cavity case. Such surface plasmon cavity with tapered 1D PhC will become a promising candidate for on-chip laser sources in the next generation optical interconnection.