  We propose a novel scheme for enhancing the quality factor of coupled
resonators optical waveguides (CROWs) when operating near a degenerate band
edge (DBE). A DBE is a four-mode exceptional point of degeneracy (EPD)
occurring when four Bloch eigenmodes coalesce providing a resonance condition
with a giant enhancement in fields. We report an unprecedented scaling law of
quality factor of CROWs when operating at the DBE, even in the presence of
losses and structural perturbations. Remarkably, the Q factor of the proposed
CROW can be engineered to exceed that of a single ring resonator having a
diameter equal to the CROW length, hence having an overall strong area
reduction. The findings reported in this letter are critical for enhancing
fields amplitudes to giant levels and the Q factor of ring resonators and are
very beneficial for various applications including four wave mixing, Q
switching, lasers, and highly sensitive sensors.
