According to an aspect, an optical system includes a laser diode configured to emit optical signals and at least two size-switchable broken racetrack ring resonators optically coupled to an optical waveguide, where each broken racetrack ring resonator is configured to exhibit a resonant wavelength. The optical system also includes a tuning arrangement associated with the broken racetrack ring resonators, where the tuning arrangement includes a micro electro-mechanical system (MEMS) or nano electro-mechanical system (NEMS) actuator mechanically coupled to a first portion of a first one of the broken racetrack ring resonators and configured to mechanically move the first portion so as to change the resonant wavelength of the first one of the broken racetrack ring resonators.