Microwave Characteristics Analysis of Photosensitive Material InP under Weak Optical Irradiation

Abstract In this paper, the microwave characteristic of photosensitive material InP irradiated by different optical signals is studied based on the coaxial resonant cavity. The coaxial resonant cavity sensor has an operating frequency range from 1 to 4 GHz, an operating mode of TEMn/4, and a quality factor of 8000 or more. According to the theory of semiconductor and electromagnetic field, the equation describing the relationship between the irradiation power and the quality factor of the coaxial resonator is derived. Additionally, in the short-time irradiation experiment, the variation of microwave characteristics of InP with irradiation power of 10mW, 50mW, 100mW, and 250mW is studied by frequency-domain and time-domain scanning methods, respectively. The measurement results indicate that the microwave characteristic variation of the InP under short-time weak power irradiation is mainly caused by the non-thermal effect, while the thermal effect is not obvious. In order to investigate the influence of thermal effect on the microwave characteristic of InP under continuous illumination, taking the irradiation power of 100mW as an example, the irradiation experiment with a duration of 1 min is performed on the InP. The thermal and non-thermal effects at the moment of opening and closing of the monochrome light source and during irradiation are analyzed. Furthermore, the stability and response speed of the system are analyzed and tested, and the measurement results are in good agreement with the theoretical analysis.