Study On Coupled Resonator Optical Waveguide

We study a new type of optical waveguide that consists of a sequence of coupled high-Q resonators—coupled resonator optical waveguide. Unlike other types of optical waveguide, waveguiding in the coupled resonator optical waveguide (CROW) is achieved through weak coupling between otherwise localized high-Q optical cavities. CROW mainly composed of ring resonators ,photonic crystal defect cavities and Fabyr -Paort cavities.CROW can find applications such as optical buffer, optical switch, optical filter,interferometer and DWDM. It's Performance parameters: dispersive relationship, group velocity, pass bandwidth, storage capability and the performance of output spectral will impact it application value. Based on tight-binding theory, we show that the group velocity, delay time and storage capacity of coupled resonator optical waveguide(CROW) strongly depends on the coupled ratio. The result is the delay time and storage capacity attenuates as the coupled ratio increased. And the group velocity and dispersion relation became large as the coupled ratio increased. Using the transfer matrix, we analyzed the influences of the coupling coefficients between micro-ring, the loss in the micro-ring and the radius of micro-ring on spectral response in the micro-ring resonator, which are relate with performance of output spectral. So as to improve the performance of output spectral response.Analysis of photonic crystal coupled resonator optical waveguide (CROW) structures with a highly dispersive (three-level EIT) background medium is presented. We can transform the ptical properties of CROW by control the control field Rabi frequency. We find that the coupling strength between nearest neighbor cavities in the CROW decreases with increasing steepness of the background dispersion, which is continuously tunable as it is directly related to the control field Rabi frequency. The weaker coupling decreases the speed of pulse propagation through the waveguide. In addition, due to decrease of the control field Rabi frequency , the bands become flatter and the absorption of the EIT media would reduce the Q-factor of the cavities. We can control the Bandwidth , delay time, Storage capacity of photonic crystal coupled resonator optical waveguide by transform the control field Rabi frequency of three-level EIT media.