一款光控频率选择表面的器件开关特性研究

Study on Switching Characteristics of Devices Loaded on Optical Frequency Selective Surfaces

研究了一款光敏电阻型开关,用以实现光控有源频率选择表面(Optically Controlled Active Frequency Selective Surface, OCAFSS)。该开关在LED等光源激励下亮态阻值可小于20Ω,暗态值接近0.2 MΩ,并随着光源强度的变化阻值可调。通过对光敏电阻内部结构的分析以及借鉴硅片型光控微波开关的建模经验,使用CST等电磁仿真软件对该开关进行了建模与仿真。经实物加工和测试,所得测试结果与仿真结果一致,显示出该光敏电阻在频段0.1~1 GHz可切换亮/暗状态,其S21参数分别为-3 dB以上和-10 dB以下,对应的传输信号可以通过或被阻挡;但随着频率的升高,开关效果不再明显,当频率大于2 GHz以后,亮暗态S21均在-7 dB以上,不再具备开关性能。对该光敏电阻的开关特性研究表明,可将其使用于特定频段OCAFSS。为验证这一结论的正确性,我们制作了一款该使用频段的吸波型OCAFSS,最终测试结果与预期值符合。

To realize Frequency Selective Surface(FSS) with controlled light, this paper explores the microwave switching characteristics of a photo-resistor. Under the excitation of LED and other light sources, the light resistance value can be less than 20 Ω, the dark resistance value can be close to 0.2 MΩ, and switch resistance is adjustable following the change of light intensity. Based on the analysis of the internal structure of the photosensitive resistance and the modeling experience of the silicon wafer optically controlled microwave switch, the CST and other electromagnetic simulation software are used to model and simulate the switch, and the physical processing and testing are carried out. The test results show that the switch can be switched in the light/dark state between 0.1-1 GHz in the operating state of OCAFSS. The S21 parameters are above-3 dB and below-10 dB respectively, and the corresponding signals can be passed and blocked. With the increase of frequency, the switching effect is no longer obvious. When the frequency is greater than 2 GHz, the light and dark S21 are all above-7 dB and the difference are very small, so the switching performance is no longer available. The switching characteristics of the photosensitive resistor show that it can be used in OCAFSS. In order to verify the correctness of this result, we made an OCAFSS of this frequency band, and the final test result is in line with the expected value.