Infrared High-gain Metal Micro-nano Optical Antenna Study

Thanks to the invention of the Nesr-field Scanning Optical Microscope (NSOM) and the continuous development of the microfabrication technology, it is possible that people investigate the optical phenomenon at nano-scale. Nowdays, the study of the nano-optics and the nano-pho tonics is in the ascendant. The surface plasmon polaritons (SPPs), a special electromagnetic mode on the interface between metal and dielectric material, is the core mechanism of the nano-photonics. It induces the free electron collective oscillation on the surface of metal,when the incident light source illuminates on the M (metal)/D(dielectric) interface. If the electron oscillation frequency matches the incident light source frequency, the surface plasmon resonance (SPR) will appear. There are high gain field enhancement and other special characteristics.Because the surface plasmon polaritons has the charatieristics of high sensitivity, it is often used in the chemical and biological detection,especially in the military. The metal micro-nano optical antenna converse the incident light into the local field to get the high field enhancement. When the metal micro-nano optical antenna is integrated with other systems, we can improve the sensitivity of the infrared detectors, reduce the system weight and make military weapons miniaturization. It can improve the S/N (signal/noise) ratio of the infrared communication system and the communication distance.In this paper, we first propose a infrared (IR) high gain metal micro-nano step-shaped dipole optical antenna, which is a good guide for the processing of the antenna. We investigate the shape and size of the metal micro-nano optical antenna that is working at far-infrared (FIR) wavelength by using the finite-difference time-domain (FDTD) method. The shape of the antenna is evolved from the dipole antenna to the step-shaped dipole antenna, at last to the bowtie antenna. We can obtain special optical properties and investigate the physical mechanism by SPPs. For all kinds of antennas,the field enhancement factor and the field distribution and the full-width of half-wave(FWHW) are compared to obtain that the bowtie antenna is optimal structure. Then, we research the planar integration of the infrared metal micro-nano optical antenna.The relation between the resonant wavelength and antenna structural parameters is investigated. At last, we deduce the formulation between the resonant wavelength and the structural parameters, which give a size guidance in the processing of the antenna. On the other hand, in order to eliminate the coupling between the infrared metal micro-nano optical antenna elements, we develop the optimal separation distance between antennas.