Research On Frequency Response Measurement Technology Of Optoelectronic Devices Based On Optical Frequency Comb

The ever-growing requirement for rapid and expansive information transmission in our current world has caused optoelectronic devices to advance at a rapid rate.As the core components of high-speed optical communications and microwave photonic systems,frequency response parameters represent the performance and operating bandwidth of the device.Accurate characterization of them plays a key role in the design,evaluation and optimization of the device itself or the overall system.Therefore,it is of great significance to correctly measure the frequency response parameters of high-speed optoelectronic devices.This dissertation has conducted research into the frequency response measurement technique of optoelectronic devices based on optical frequency comb(OFC),which is primarily composed of the modulation coefficient and half-wave voltage measurement method of Mach-Zehnder modulator(MZM)and the frequency response measurement method of photodetector(PD).The main research contents of the dissertation are as follows:(1)For the frequency response measurement of optical modulators:A frequency response measurement method of optical modulators is proposed based on MLLD(Mode-Locked Laser Diode)optical frequency comb.Using the wide optical spectrum and high coherence of the optical frequency comb to realize the down-conversion of high frequency signal,the amplitude of the beat component of the optical frequency comb and modulation signals at different driving power is detected and analyzed by the electrical signal analyzer(ESA)to eliminate the influence of OFC and PD,and then the modulation coefficient and half-wave voltage of MZM in the frequency range of 40 GHz are obtained.In fact,low frequency detection saves the bandwidth requirements of detection devices;A frequency response measurement method of optical modulator is proposed based on the two-combs optical frequency comb.With the two-combs optical frequency comb generated by the frequency shift heterodyne as the light source,the absolute frequency response parameters of the MZM to be measured in the frequency range of 40 GHz are obtained by detecting and analyzing the amplitude of the fixed-frequency signal(f_s)in the electrical domain of the ESA under the ON-OFF working conditions of the MS(Microwave Source),and the self-calibrated measurement is realized by the fixed-frequency detection,which saves the bandwidth of the adjuvant devices.(2)For the frequency response measurement of photodetector:A photodetector measurement method is proposed based on optical frequency comb.Using low-repetition frequency MLLD as the OFC light source,using the wide optical spectrum and high coherence of optical frequency comb to realize the up-conversion of low frequency signal,analyzing the amplitude of the beat frequency component by each comb tooth of OFC and the modulated signal by ESA,the influence of MZM was eliminated.Dividing the measurement frequency range into 5 segments(M=5)the influence of OFC was eliminated by segmented measurement by configuring the half-frequency modulation frequency in the frequency range of 2.324 GHz(Nf_r/2),and then the relative frequency response of the PD was obtained in the frequency range of 23.240 GHz(M×N×f_r),extending ten-fold(2 M)frequency range.Moreover,the output of the MS frequency was controlled by sweeping the frequency in the range of 11.62 MHz(f _r/2),which achieved the relative frequency response of the PD at a resolution of 500 k Hz avoiding extra electrical to optical calibration.