Coupling Light Wave Into Waveguide Through Optical Antenna

In optical integration, investigations on light control of mainly are classified as light excitation, propagation, route and transformation. A waveguide is an important carrier to guide energy in optical integration and light need to be coupled from free space into waveguide. The common coupling ways are grating coupling, prism coupling and antenna coupling. In order to improve the coupling efficiency, this thesis studies light is coupled into subwavelength waveguide by the optical antenna. The interactions between light and structures are simulated by the finite difference time domain method(FDTD), and the main research contents are as follows:1. Light is coupled from free space into waveguide by H-shaped antenna. Based on the near-fields enhancement effect of resonant antenna, the H-shaped optical antenna is designed to couple wave from free space into metal waveguide in the communication wavelength range, The parameters of the antenna are optimized for highly coupling efficiency through the FDTD method. The results shows that H-shaped antenna's coupling efficiency is higher than that of dipole antenna.2. Light is coupled from free space into subwavelength waveguide. Through antenna resonance, light wave in free space can be coupled into waveguide. Reflector is added under antenna to reflect the transmitted wave. This is to improve the utilization of incident light and coupling efficiency. The FDTD method was employed to simulate the interaction of wave and metal structure. Result shows that the coupling efficiency is increased by adding reflector, with the maximum reaching to 27.8%.3. Light is coupled from the dielectric waveguide into the plasma waveguide. The optical antenna is added at the junction of the dielectric waveguide and the plasma waveguide. The antenna resonance enhances the intensity and couples the energy from silicon waveguide to metal waveguide. The FDTD method was employed to simulate the interaction of light wave and metal structure. We optimize the structure parameters of antenna through matching light path impedance. The coupling efficiency are enhanced, reaching 78.2%.