Quantum and thermal noise limits of coupled resonator optical waveguide and resonant waveguide optical rotation sensors

We analyze theoretically the performance limitations of coupled resonator optical waveguides (CROWs) and a single passive resonator of the same area for rotation sensing applications. We show that when the dominant noise sources are of quantum (shot) or thermal origin, the single passive resonator outperforms the CROW regardless the propagation loss in the waveguides. We also show that optimizing the design parameters of the CROW and the single ring cavity according to the dominant noise source can improve the minimal detectable rotation rate by almost 50%.