title: Extinction-ratio-independent electrical method for measuring chirp parameters of Mach-Zehnder modulators using frequency-shifted heterodyne.
abstract: An extinction-ratio-independent electrical method is proposed for measuring chirp parameters of Mach-Zehnder electric-optic intensity modulators based on frequency-shifted optical heterodyne. The method utilizes the electrical spectrum analysis of the heterodyne products between the intensity modulated optical signal and the frequency-shifted optical carrier, and achieves the intrinsic chirp parameters measurement at microwave region with high-frequency resolution and wide-frequency range for the Mach-Zehnder modulator with a finite extinction ratio. Moreover, the proposed method avoids calibrating the responsivity fluctuation of the photodiode in spite of the involved photodetection. Chirp parameters as a function of modulation frequency are experimentally measured and compared to those with the conventional optical spectrum analysis method. Our method enables an extinction-ratio-independent and calibration-free electrical measurement of Mach-Zehnder intensity modulators by using the high-resolution frequency-shifted heterodyne technique.
authors.forename: Shangjian
authors.initials: S
authors.lastname: Zhang
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.forename: Xinhai
authors.initials: X
authors.lastname: Zou
authors.forename: Yali
authors.initials: Y
authors.lastname: Zhang
authors.forename: Rongguo
authors.initials: R
authors.lastname: Lu
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu