STUDY ON WAVEGUIDE-TYPE ELECTRIC-FIELD SENSOR USING NONLINEAR POLYMER FOR PRECISELY MEASURING ELECTROMAGNETIC NOISES.

点击翻译按钮获取中文摘要

Recently, accompanied with the popularization and the higher speed operation of electronic equipments as personal computers, electromagnetic wave noises with wide frequency range affect other electronic equipments and occasionally lead to mis-operation. We then study a wideband electric-field sensor to measure precisely the electromagnetic noises. The sensor is composed of a wideband planar small antenna and a wideband optical modulator using a nonlinear polymer.We analyze and design a small planar bow-tie antenna which is expected to be wideband. It is seen that the antenna has wider bandwidth than a planar dipole antenna, and it becomes the widest at a bow-tie angle of 90 deg. Furthermore, an antenna that each side opposite to the knot of the bow-tie change from, a straight line to an arc, has much wider bandwidth.We design an optical modulator in which the material of optical waveguide is the side-chain type nonlinear polymer,3RDCVXY with small wavelength dispersion, and the simple coplanar waveguide (CPW) is used. To make channel' waveguides with the photobleaching method, we measured the decrease in refractive index by uv exposure and confirmed that the decrement is stable with time. We could design the modulator with both the impedance matching and the velocity matching between the optical wave and the modulating microwave. As the result, we obtain the designed modulating bandwidth of 496 GHz at an interaction length of 2 cm.At this condition the bandwidth is decided only by the propagation loss of the CPW. We made the designed CPW and measured the loss. The measured loss is over 10 dB/cm at this time, and the large loss suggests a bandwidth of 30 GHz at an interaction length of 2 cm. We plan to improve the fabrication method and the propagation loss to go near the bandwidth to the designed one.