Transmission and group delay in a double microring resonator reflector

We present a microring resonator scheme for an optical reflector in which two microrings are coupled to two bus waveguides, to produce reflected signal at the input port. In this system, a single narrow reflected peak with maximum reflectivity near 100% in a wide spectral range due to the Vernier effect are achieved. We also investigate versatile reflection, transmission spectra and group delay characteristic. These effects are useful for applications in ring resonator-based photonic devices such as all-optical single wavelength tunable laser end mirrors, reflective wavelength switching, reflective filter and dual-wavelength delay line.