Research On Reconfigurable Optical Add-Drop Multiplexer Based On Microring

Optical Add-Drop Multiplexer is one of the key components in WDM optical networks, which is developing along the direction of tunable wavelength and low crosstalk. The reconfigurable optical add-drop multiplexer based on microring have attracted considerable attention because of compact structure, favorable wavelength selectivity and the compatibility with the mature CMOS process.Based on the coupled mode theory and transfer matrix method, the effect of cross coupling coefficient at the intersection of Optical Add-Drop Multiplexer based on microring on output spectrum is analyzed theoretically and the numerical simulation and FDTD simulation are compared. The simulation results show that output spectrum appears like an asymmetric Fano-resonance line shape because of the existence of loss at the cross. As the cross coupling coefficients decrease, spectral lines convert gradually from Fano-resonance line shape to symmetric Lorentzian line shape with respect to the resonant wavelength.In order to reduce the effect from insertion loss at the intersection on output spectrum, the multimode interference couplers based on lined-tapered are introduced. Based on the self-image mechanism, the structure parameters are optimized using finite-difference time-domain (FDTD) method. The output spectrum and field distribution are compared between the ROADMs based on traditional structure and lined-tapered structure. The results show that the latter have better symmetric spectrum and lower insertion loss.The reconfigurable optical add-drop multiplexer based on cascaded microrings are discussed and demonstrated to overcome these shortages of uneven pass band and large crosstalk. The output spectrum are compared and analyzed between the ROADMs based on tradition structure and lined-tapered structure. The simulations show that the latter have better box spectral response, steeper resonant peaks, lower scattering loss and crosstalk. Based on the electro-optic modulation theory, the resonant wavelengths can be dynamically tuned by different manners of operation temperature on the microrings. The smaller interchannel crosstalk can be obtained by inflict appropriate temperature on the microrings, which can help for the fabrication and application of the devices.