Si-MZI racetrack micro-ring resonator circuits for wavelength division adjustment – way to generate optical digital patterns

Silicon (Si) photonic components, namely, grating couplers and three-port splitters and couplers, have been designed and combined to form double-stadium Si-Mach–Zehnder interferometer (MZI) racetrack microring resonator circuits for efficient control over resonance in a certain wavelength range and free-spectral range (FSR). It was found that variable microring resonator arms and the values of free-space distance (between the arms) at 200 nm and 5 µm can yield two and six OFF-phase zones, respectively, within the wavelength range of 1.5–1.6 µm. Furthermore, it was observed that the smaller arms downsize the FSR, whereas the larger arms upsize its value within the transmission spectrum. The usefulness of these structures can be conceptualized in the area of optical digital pattern code generation because suitably controlling the MZI arm lengths would create certain optical digital patterns in the frequency domain of operation. Apart from these, the usefulness of racetrack optical delay lines remains in optical sensing or biomedical sensing as well.