Research On Measurements Of High Speed Photodetectors

The research work of this thesis was supported by the sub-project one "Theory on heterogeneous materials compatibility and Key Structure & Technology Innovations for Monolithic Integrated Optoelectronic Devices" (Project No.2003CB3149001) of the 973 project "Basic Research on Integrated Optoelectronic Devices and Microstructure Optical Fibers with Structure and Technology Innovations for Future Advanced Optical Communications"(project No. 2003CB314900 ), national nature science key projects "Research in the material and fabrication method of GaAs/InP taper structure and applications in the novel opt-electronic devices "(project No. 9001002), the 2nd stage project of 111 project "Communications and network technology innovation and personnel core base" (project No. B07005) and Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0609) , MOE, China.Along with the development of information technology, optical communication technologies have been pushed towards ultra high speed characters. The parameters of Photodetectors, which is the core device in optical communication systems, such as dark current, responsivity, quantum efficiency, frequency response and nonlinear characters, should be measured precisely. And these parameters could be used to design and fabricate new photodiodes.In this master's thesis, almost all important parameters of photodetectors and how to measure these parameters are introduced, Two normal method of measuring the frequency response of photodetectors, light wave component analyzer and optical heterodyne method, were analyzed and many measurements has been taken to prove the conclusions. The research results can be summarized as follows:1. Parameters of photodetectors, such as I-V character, dark current, responsivity, quantum efficiency and frequency response, and how to measure these parameters are introduced.2. The principle of light wave component analyzer is introduced here and the meaning of S parameters of photodiodes is given. Three small signal model of photodetector is analyzed and the parameter is extract and the model is simulated by ADS.3. A systematic calibration method of measuring photodetector frequency response based on optical heterodyne technique is approved. The expression of photodetector frequency response is achieved by analyzing the fundamental principle of optical heterodyne. It is found that the main reason of influencing the measurement results is the instable light of lasers during tuning. Experiments improve that the calibration method is feasible and effective.4. Nonlinear phenomenon is observed during measuring the frequency response, and the principle is analyzed, and the conclusions are corresponding to the result that measured.5. The automatic measurement system of measuring the reflection/ transmission spectrum and the response spectrum is established by using C# and VISA architecture.