We propose a digital filter design method for high-order series-coupled microring resonator (MRR) filters considering coupling loss in coupling areas. This method makes it possible to design high-order MRR filters with desired parameters such as a 3 dB wavelength bandwidth, free spectral range (FSR), and center wavelength, which have been difficult to design so far. It is possible to apply the proposed design method to design MRR filters based on the Vernier effect with an expanded FSR. We demonstrate fourth-order Butterworth and Chebyshev silicon-based MRR filters designed with the proposed method. The 3 dB wavelength bandwidth, FSR, and center wavelength of the designed MRR filter are almost identical with the target values.
We experimentally demonstrate all-optical flip-flop and inverter operations using two adjacent lasing wavelengths in a quantum-well microring laser, and that the state is switched between the flip-flop and inverter operations by changing the phase in the outer cavity composed of busline waveguides. We also propose multimodal rate equations for a microring laser taking into account clockwise and counter-clockwise light propagations. By comparing experimental results and simulated results based on the rate equations, the principle of the switching between the flipflop and inverter operations is clarified.
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