Abstract
The add drop filter (ADF) is one of the most significant devices for coarse wavelength division multiplexing (CWDM) systems to add and/or drop a required channel individually from multiplexed output channels without disturbing other channels. The important parameters of the ADF are coupling efficiency, dropping efficiency, passband width and Q factor. Photonic crystal (PC)-based optical devices have attracted great interest due to their compactness, speed of operation, long life period, suitability for photonic integrated circuits, and future optical networks. Here, an extensive overview of a photonic crystal ring resonator (PCRR)-based ADF using a different shape of ring resonator is presented, and its corresponding functional parameters are discussed. Finally, the designed circular PCRR-based ADF for an ITU-T G 694.2 CWDM system is presented. Approximately 100% of coupling efficiency and dropping efficiency, 114.69 of Q factor, and 13 nm of passband width is obtained through simulation, which outperforms the reported one.
Highlights
The exponentially increasing bandwidth requirements for internet generation and multimedia applications is pushing optical communication ever closer to the end user
Owing to the above-mentioned reasons, here we have considered photonic crystal ring resonator (PCRR)-based add drop filter (ADF)
The normalized transmission spectra of square PCRR-based ADF is depicted in Fig. 5(b) where the coupling efficiency, dropping efficiency, and spectral selectivity of the filter is poor
Summary
The exponentially increasing bandwidth requirements for internet generation and multimedia applications is pushing optical communication ever closer to the (last mile) end user. When the radius of the ring resonator decreases below 5 μm, propagation and bending losses increase exponentially They affect coupling and dropping efficiencies, passband width, and in turn, the Q factor of the filter. Photonic crystal ring resonator (PCRR)-based ADF is one of the right candidates to overcome this issue, as it does not allow these losses to increase exponentially. By introducing a defect (point or line or both) in these structures, the periodicity and the completeness of the band gap are broken and the propagation of light can be localized in the PBG region.[5,6] Such an outcome allows realization of a wide variety of active and passive devices for optical communication.
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