  We propose and experimentally demonstrate the enhancement in the filtering
quality (Q) factor of an integrated micro-ring resonator (MRR) by embedding it
in an integrated Fabry-Perot (FP) cavity formed by cascaded Sagnac loop
reflectors (SLRs). By utilizing coherent interference within the FP cavity to
reshape the transmission spectrum of the MRR, both the Q factor and the
extinction ratio (ER) can be significantly improved. The device is
theoretically analyzed, and practically fabricated on a silicon-on-insulator
(SOI) wafer. Experimental results show that up to 11-times improvement in Q
factor, together with an 8-dB increase in ER, can be achieved via our proposed
method. The impact of varying structural parameters on the device performance
is also investigated and verified by the measured spectra of the fabricated
devices with different structural parameters.
