Analysis of an All-Optical Microwave Mixing and Bandpass Filtering with Negative Coefficients

In this paper, an all-optical signal processor that performs both microwave mixing and bandpass filtering with negative coefficients is investigated. The negative coefficients are obtained by locating the optical carriers at the opposite slopes of the Mach-Zehnder optical filter, for the PM-IM conversion. We present a general model for using in a radio-over fiber link. The RF signal can be recovered by the proposed signal processor without any distortion. We demonstrate a wide tuning range, good performance, and easy implementation of multitap filters in an all-optical passive configuration. The proposed filter provides an improvement to the mainlobe-to-sidelobe ratio and a reduction to the mainlobe bandwidth.