Tunable microring based on-chip interrogator for wavelength-modulated optical sensors

An interrogation system for wavelength-modulated optical sensors based on tunable microring filter has been proposed and demonstrated both theoretically and experimentally. The wavelength shift of the sensors can be readout from the shift of the peak optical output of the system by scanning the resonant wavelength of the microring filter. We fabricate the interrogator on the silicon-on-insulator platform and a fiber Bragg grating sensor (FBG) is precisely interrogated. The Lorentz spectrum of the microring filter can de-flatten the output spectrum of the FBG and improve the interrogating resolution efficiently. Such a technique potentially provides a compact (only 50×50 μm2), low-cost, and high-performance (1 pm resolution) approach for the interrogation of the wavelength-modulated sensor and distributed sensor arrays.