A photonics-based ultra wideband scanning RF receiver with high sensitivity and dynamic range

This paper presents an innovative photonics-based ultra wideband RF receiver for spectrum sensing applications. The scheme scans the RF spectrum at discrete steps, down-converting at baseband single portions of the detected spectrum, where they can be precisely acquired. The down-conversion is performed modulating a tunable optical carrier with the RF signal, and beating it with an optical local oscillator. The selection of the desired spectrum portion is achieved tuning the wavelength of the optical carrier, avoiding tunable optical filters and allowing a fast scanning of the detected spectrum. The phase locking between the carrier and the local oscillator by means of a coherent optical comb generator ensures very low phase noise. An experimental validation shows an RF input range of 0.5÷9.5 GHz, with high sensitivity and dynamic range. Increasing the number of comb lines by enhancing the comb generation, the architecture has the potential to detect RF signals up to 100GHz. Moreover, implementing the scheme through integrated photonics technologies will ensure high environmental stability and reduced size weight and power consumption, meeting the increasingly stringent requirements of RF spectrum sensing applications.