Cascaded Optical Ring Resonator

An optical detector, comprising:

• a cascaded optical ring resonator comprising an input optical waveguide having an input end and an output optical waveguide having an output end, and a plurality of closed-loop optical waveguides that are each optically coupled to the input optical waveguide for allowing light to couple from the input optical waveguide into the closed-loop waveguide, and that are each optically coupled to the output optical waveguide for allowing light to couple from the closed-loop waveguide into the output optical waveguide;
• a tunable monochromatic light source configured to couple light into the input end of the input optical waveguide, wherein the light source is configured to vary a frequency of the light coupled into the input end of the input optical waveguide within a scanning range;
• a detecting unit optically coupled to the output end of the output optical waveguide and configured to output a detector signal;
• and
• a processing unit for processing the detector signal;
• wherein the processing unit is configured to obtain transform, T, data by performing a first transform on the detector signal, to select respective T data for each of the closed-loop optical waveguides among the T data, and to perform a second transform being an inverse of the first transform on the selected respective T data for each of the closed-loop optical waveguides;
• wherein the first transform is configured for transforming data in the time domain to data in the frequency domain.