Silicon RF-Photonic Filter and Down-Converter

An RF-photonic filter and down-converter system based on a compact and fully tunable silicon optical filter has been demonstrated and analyzed. Its frequency down-conversion was implemented using optical heterodyne detection with an injection locked laser. This system filters a 1.25 GHz-wide signal with > 20 dB filter rejection and a very broad 20 GHz center tuning range. The frequency down-conversion process is operated in a low-IF mode to avoid laser low frequency noises. Measured system Spurious-Free Dynamic Range (SFDR) of 94.3 dB*Hz^2/3 has been limited by the optical losses from I/O coupling and measurement setup. We examined experimentally that 105.3 dB*Hz^2/3 SFDR is achievable if the encountered optical loss were reduced to the filter´s intrinsic loss. Based on the excellent agreements between measured and simulated results, we explore the critical improvements of the silicon photonic devices needed for the system to achieve 118 dB*Hz^2/3 SFDR and briefly review the status of the component technologies.