Research On Detection Technology Of Weak Light Signal Based On The Microwave Resonance Method

Optical signal detection is one of the critical technologies in the fields of radio-over-fiber wireless communication,microwave/optical dual-mode guidance technology,and starry sky exploration.Its weak light detection performance directly reflects the state-of-the-art of detection-related fields.At present,the research focus of light detection technology is mainly on the improvement of the response characteristics,material composition,and structural form of the detector,while most of the detection methods are still to convert the light response of the detector into the electrical response for detection through various detection circuits.And there are few studies on using other detection methods to improve the working performance of the detector.Therefore,it strongly necessitates developing a new high-sensitivity weak light detection technology to contribute to the innovation of the light detector.Based on the interaction mechanism between light and microwave,and the characteristics of high accuracy,fast response speed,and high response sensitivity of microwave resonance method,the research on weak light signal detection technology based on microwave resonance method is proposed innovatively in this dissertation.Based on the existing test methods and systems,a test method and evaluation method for the evolution law of dielectric properties of sensitized materials under irradiation is proposed,which verifies the microwave response mechanism and response mechanism of sensitized materials.Then,for the main influencing factors of optical signal detection technology,the technical method of using microwave resonator as optical signal test sensor is proposed,which realizes the detection from optical response to microwave response,and improves the weak light signal detection ability of the test system.In addition,the microwave test sensor itself is used as the microwave bias source on the detector,which reduces the influence of the internal noise of the device and the external bias source on the weak light signal test results.And the weak light with the irradiation power of P<2×10-10W,the response of R?0.48dB/nW,the response time of ??l.36ms,the noise equivalent power of NEP?7.797×10-14 W/(?),and the specific detection rate of D*?2.751×1012cm·(?)/W is measured successfully.The results indicate that when the detectors are cadmium sulfide(CdS),the weak light signal detection technology based on the microwave resonance method improves the performance indexes such as NEP and D*by one order of magnitude.The main contents and contributions of this dissertation are summarized as follows:1.The interaction of the light,microwave,and semiconductor is analyzed in detail.Then,according to the research status of weak light detection technology at home and abroad,taking the microwave response characteristics of semiconductor sensitized materials as the bridge,a new weak light detection technology based on the microwave resonance method is proposed,which reduces the noise content of the test system and improves the weak light signal detection ability.2.The field distribution and energy distribution of the re-entrant coaxial resonator and the quasi-optical resonator are analyzed and calculated,which are proved by simulation.Then,the equation between the irradiation power and the dielectric properties of the sensitized material is established,which provides a theoretical basis for studying the dielectric properties of sensitized materials under irradiation.Finally,the equivalent circuit theory and the normal mode helical antenna theory are analyzed,and the equation between the irradiation power and the resonance parameters of the microwave sensor is established,which provides theoretical support for the weak light detection based on the microwave resonance method.3.Based on the theory of microwave resonance test method and the semiconductor material sensitization,the test models and systems of sensitized materials dielectric properties by re-entrant coaxial cavity method and quasi-optical resonator method are constructed respectively,and the evolution law of dielectric properties with irradiation light intensity is obtained.In addition,the time-domain and frequency-domain scanning methods are used to study the variation of microwave performance of the test sensor under irradiation.Then the influence of thermal effect on the test results in short-time and long-time irradiation is analyzed,and the microwave response characteristics and mechanism of semiconductor sensitized materials are further clarified.The results verify the feasibility of the weak light signal detection technology based on the microwave resonance method.4.According to the test results of the dielectric properties,the photoresistor is loaded on the microwave resonance sensor to combine the photosensitive characteristics of the sensitized material with the microwave resonance characteristics of the test sensor.Thus,the optical response of the detector will be transformed into the microwave response for detection.Then,the weak light test models and systems of the open-ended coaxial cavity method and the normal mode helical antenna method are constructed respectively.And the frequency-domain and time-domain scanning methods are used to study the weak continuous light signal and modulated pulse light signal.In addition,the weak light signal detection technology based on the microwave resonance method is theoretically analyzed,experimentally verified and compared in terms of noise and technical indexes.The results indicate that the weak light test system designed in this dissertation has the advantages of high response sensitivity,fast response speed,low noise equivalent power.