Narrow-bandwidth silicon photonic CROW filter for carrier-extracted self-coherent (CESC) detection

In this Letter, we report a second-order silicon photonic (SiP) coupled resonator optical waveguide (CROW) filter with an ultra-narrow 10-dB bandwidth of 1.75 GHz and a high extinction ratio (ER) of ∼50 dB. By utilizing this CROW filter, we demonstrated an innovative self-coherent detection, called carrier-extracted self-coherent (CESC) detection. By effectively suppressing signal components with the narrow-bandwidth CROW, full-field recovery can be achieved without expensive coherent lasers and sophisticated iteration algorithms. The performance of the CROW filter-based CESC system was further experimentally verified by retrieving 100 Gb/s QPSK signals.