This work presents the performance analysis of ring resonator-based tuneable optical filters, namely the influence of the design parameters such as coupling coefficient (k), coupler loss coefficient (a) and operating temperature (t) on the optical performance of the filter. Computed results have shown that a and k dramatically influences the performance of the add-drop filter, the operating temperature can effectively be used as a mechanism of selecting the desired frequencies within the dynamic range of the filter, and special attention should be paid to the operating temperature range of the filter in order to avoid a decrease of its free spectral range below the value of the desired pass bandwidth. Preliminary sensitivity analysis has also revealed that the single ring add-drop filter design is almost insensitive to the relative position of the two optical couplers onto the ring, and therefore very versatile for integration into a photonic chip.
This work proposes and analyses a sparse reconfigurable optical add/drop multiplexer consisting of eight tuneable ring resonator-based optical filters, and two eight channel arrayed waveguide routers. The design features a 0.25 add-drop factor, 32 channels in a four-skip-one architecture at 0.8 nm channel spacing, covers the conventional band, and takes advantage of the main limitation of single ring resonator-based optical filters, namely the rather limited free spectral range. Coupled mode theory and its transfer matrix formalism have been used to design the tuneable add-drop filters, while classical theory of signal spectral analysis have been used for determining its performance characteristics. The computed results for a sparse tuneable optical add-drop multiplexer equipped with single-ring add-drop filters were add/drop insertion loss 0.77 dB, through adjacent insertion loss 2.7dB, worst add/drop adjacent cross talk -43dB, add/drop bandwidth at full width half maximum 0.221 nm, and group delays between 0.05 ps and 2 ps for add/drop and through optical channels. The proposed tuneable OADM exhibits a very good magnitude response and properly adds, drops, removes and/or lets through the selected channel without disturbing the other channels.
This work presents the analysis of ring resonator based tuneable optical filters and their proposed application in wavelength division multiplexing transmission systems. Using coupled mode theory and its transfer matrix formalism it has been shown that single-ring resonator add-drop filters with coupling coefficients k can provide similar or better performance than double ring resonator add-drop filters with coupling coefficients k/2, while benefiting from simple and more robust designs, simplified tuning control, and easier manufacturing. Further analysis of the their dynamic range showed that thermally tuneable single-ring add-drop filters can easily cover four optical channels at 0.8nm spacing. Their proposed application is a sparse reconfigurable optical add-drop multiplexer with 0.25 add-drop factor and 32 channels at 0.8nm channel spacing that can be utilized in linear, ring, and mesh all-optical WDM networks/transmission systems.