Analysis of System Imperfections in a Photonics-Assisted Instantaneous Frequency Measurement Receiver Based on a Dual-Sideband Suppressed-Carrier Modulation

Instantaneous frequency measurement receivers are a well-established technology that is used for the ultrafast characterization of pulsed microwave signals over a broad bandwidth. Recently, numerous photonic approaches to instantaneous frequency measurement (IFM) have been proposed and experimentally demonstrated, with the ultimate aim of leveraging the benefits of optical technology to improve the performance of already existent electronic solutions. Despite the numerous results, not so much attention has been paid so far to understand the subtle implications that system imperfections can have on realistic photonics-based IFM receivers. Here, we focus our attention on one of the most promising among these IFM techniques, which is based on optical power monitoring of a dual-sideband suppressed-carrier modulation after a Mach-Zehnder interferometer (MZI) filter. We develop a time-domain model for the rigorous analysis of all major optical and electrical effects, including amplitude imbalance and phase errors in the modulator and the MZI, as well as on-pulse RF phase/frequency modulation. Simulations are then used to illustrate the substantial effect that a nonperfectly suppressed optical carrier can have on system performance. More importantly, it is shown that in a nonideal situation, the system amplitude comparison function critically depends on input RF power, thus greatly limiting the dynamic range of the photonics-based receiver. Some approaches to solve these issues are also discussed.