Study On The Calibration Technique Of Field-effect Self-mixing Terahertz Detector

With the practical application of terahertz detectors in the fields of object imaging,nondestructive testing,medical diagnosis and so on,the traceability of terahertz detectors is urgently needed to ensure its effective application and reliability of measurement.Field-effect self-mixing terahertz detectors have important applications in room-temperature high sensitivity terahertz detection due to their high sensitivity and fast response.In order to ensure their accuracy and reliability of the measurement results,taking the terahertz radiometer developed by the National Institute of Metrology as the metrology standard,we develop a study on the calibration technique of field-effect self-mixing terahertz detector.The main research contents and innovations are as follows:(1)Studying on the responsivity calibration method for field-effect self-mixing terahertz detector.On the basis of analyzing the existing calibration methods of detectors,the standard terahertz detector substitution method is selected to calibrate the field-effect self-mixing terahertz detector,aiming at the problem that it is difficult to coordinate the incident light power range and the response speed between the standard detector and the tested detector by the direct substitution method,an indirect calibration method is proposed to solve the problem of traceability of the field-effect self-mixing terahertz detector with high response.(2)Manufacturing a field-effect self-mixing terahertz detector calibration device.The optical module can ensure that the received power values of each detector are consistent to achieve absolute responsivity calibration and a monitoring detector is added to the optical path to correct the influence of the light source instability.We also add displacement control module and data acquisition module.Besides,we develop an automated test system for terahertz spot power distribution,so we can analyze the quality of the terahertz spot in the calibration device and optimize the device to meet the calibration requirements.(3)Performing the calibration experiment and uncertainty analysis.Calibration experiments are performed on two field-effect self-mixing terahertz detectors using developed calibration device and uncertainty analyses are performed.At the same time,the calibration results are verified by comparison experiments in the National Institute of Metrology,the results show that:the normalized deviation E_n of the two calibration results is less than 1,which meets the requirements of consistency evaluation and verifies the feasibility and accuracy of the calibration method and device.