Comb-Based RF Photonic Filters Based on Interferometric Configuration and Balanced Detection

We demonstrate a novel technique to improve radio frequency (RF) performance such as RF gain and noise figure (NF) for comb-based RF photonic filters. While conventional RF photonic links use a dual-output modulator and balanced detection, this RF photonic filter utilizes an interferometric configuration with double sideband suppressed carrier modulation and balanced detection. This technique can simultaneously provide filter tunability, 6-dB RF gain increase, and noise cancellation. The RF gain and NF of the RF photonic filter are improved to approximately 0 and 24 dB, respectively. With the improved RF performance, we perform the tuning of the filter center frequencies from 2 to 8 GHz with no baseband filter response (<;-38 dB), no RF power fading, while maintaining good filter shape (sidelobe suppression and stopband attenuation >32 dB).