Research On Power Correction In High-frequency Characterization Of High-speed Optoelectronic Devices

High-speed optoelectronic devices are the key elements of optical fiber communication systems and microwave photonic links.Therefore,high-frequency characterization of optoelectronic devices has always been a research hotspot.A measurement method of frequency response of optoelectronic devices based on frequency-shifted heterodyne,which has the advantages of multi-device,multidimension,self-calibration,high-resolution,has a promising application prospect.With the higher requirements for the spectral efficiency of optical communication systems and performance of microwave photonic links bring the higher requirements for the accuracy of measurement methods of frequency response of optoelectronic devices.The deviation caused by the power approximation in the measurement method based on frequency-shifted heterodyne is no longer negligible.Consequently,a power correction method for the frequency measurement system is urgently needed.In this thesis,we dedicate to solving this problem.By analyzing the transmission line theory,the physical meaning of several power in microwave network is clarified,based on which several theoretical microwave network models are established refer to the requirements of different types of power calibration of the measurement methods.Two power correction method including source power calibration and receiver power calibration are proposed,then successfully applied to the measurement method based on frequency-shifted heterodyne.The main research contents of this thesis are as follows:1.A power correction method for microwave source is proposed and applied to the frequency response measurement of electro-optic phase modulator.The method solves the problem that the reflection coefficient of the microwave source is unable to be characterized under the working state by cascading an amplifier to microwave source to measure reflection coefficient of the equivalent structure.Therefore,the accurate load absorption power can be measured.The method is researched by systematically theoretical,simulative and experimental demonstrations.The method is applied to the frequency response measurement of electro-optic phase modulator based on frequencyshift heterodyne to improve the experimental structure.The exact driving power of the modulator is obtained through the equivalent source power calibration;thus,the halfwave voltage of the modulator is obtained.The comparison between the test results before and after calibration with the standard shows that this correction method significantly improves the accuracy of the frequency response measurement results of the electro-optic phase modulator.2.A receiver power correction method for spectrum analyzer is proposed and applied to the frequency response measurement of the photodetector.The method corrects the received power of the spectrum analyzer by measuring the frequency response of the spectrum analyzer under the specific parameter settings.The method is researched by systematically theoretical and experimental demonstrations,and applied to the frequency response measurement of photodetector based on frequency-shifted heterodyne.Through the frequency response measurement of the spectrum analyzer,the output power of the photodetector is corrected,therefore,the exact responsivity of the photodetector is obtained.The comparison between the test results before and after correction with the standard shows that this correction method significantly ameliorates the measurement method of frequency response of photodetector based on frequencyshifted heterodyne.