Development of Swept Frequency Method for Measuring Frequency Response of Photodetectors Based on Harmonic Analysis

We develop a swept frequency method for measuring the frequency response of photodetectors; (PDs) based on harmonic analysis. In this technique, a lightwave from a laser source is modulated by a radio-frequency (RF) signal via a Mach-Zehnder LiNbO3 modulator, and detected by a PD under test. The measured second-order harmonic of the RF signal contains information of the frequency responses and nonlinearities of the RF source, modulator, and PD. The frequency response of the PD alone is obtained by deducting the known frequency responses and nonlinearities of the RF source and modulator. Compared with the conventional swept frequency method, the measurement frequency range can be doubled using the proposed method. Experiment results show a good agreement between the measured results and those obtained using other techniques.

National Natural Science Foundation of China 60510173 60536010605060066060601960777029National Basic Research Program of China 2006CB604902 G2006CB302806 2006DFA11880 This work was supported in part by the National Natural Science Foundation of China under Grants 60510173,60536010,60506006,60606019, and 60777029, and in part by the National Basic Research Program of China under Grants 2006CB604902, G2006CB302806, and 2006DFA11880.