Theoretical investigation of the capture effect in IMDD-based microwave photonic mixers

摘要

We study the large-signal behavior of microwave photonic (MWP) mixers to investigate the small-signal suppression phenomenon commonly referred to as the capture effect. We introduce and theoretically study the capture effect in the context of MWP mixers. Theoretical expressions are derived for calculating the capture effect in three basicMWP mixer types based on intensity-modulation direct-detection (IMDD). We show that the capture effect not only is a function of the power ratio between the input radio-frequency (RF) signals to the MWP mixers, but also depends on the absolute value of their powers. In addition, it is shown that the capture effect of an IMDD-based MWP mixer depends on the fiber dispersion and chirping of the optical modulator, but does not depend on the noise of its components and bias drift of the optical modulator. We extend the study to different unequal-power frequency components of a signal, and as a practical example, we investigate the capture effect when a narrowband FM signal is applied to the RF input of an IMDD-based MWP mixer, theoretically demonstrating considerations and limitations in using MWP mixers. (c) 2018 Optical Society of America