Experimental assessment of photonic down-conversion techniques for analog new-radio upstream

This paper explores the feasibility of Intermediate Frequency (IF) detection from a directly modulated Radio Frequency (RF) optical signal. We propose a method involving optical series re-modulation of an RF over Fiber (RFoF) signal and a down-converting frequency, resulting in unmodulated and modulated optical carrier repetitions separated by the target intermediate frequency. Two approaches are examined: employing a null point biased Mach-Zehnder Modulator (MZM) for electrical frequency doubling and utilizing intensity modulation for power efficiency.