Efficient design of optical delay lines based on slotted-ring resonators

In this study, a novel design of coupled-resonator optical waveguide delay line based on slotted ring resonators (SCROW) is proposed and analysed. The coupling efficiency between the resonators, which can be controlled either by changing the slot position inside the cavity or by varying the separation distance between the rings, plays an essential role in controlling both group velocity and delay time of the suggested SCROW. The simulation results are obtained using multi-resolution time domain scheme in conjunction with uniaxial perfectly matched layer boundary conditions. By introducing a slot inside the microring resonator of the suggested structure, a quality factor of about 5 × 10³ and high delay time are obtained with small ring size.