HETEROGENEOUSLY INTEGRATED SENSOR

A device comprises at least one of the first, second and third elements fabricated on a common substrate. At least one of the first elements comprises an active waveguide structure supporting an active optical mode. At least one of the second elements comprises a passive waveguide structure supporting a passive optical mode. At least one of the third elements, at least partly butt-coupled to at least one of the first elements, comprises an intermediate waveguide structure supporting intermediate optical modes. At least one of the second elements comprises at least one input/output structure configured to interact with an analyte region and at least one of the first elements comprises an optical source. Mutual alignments of the elements are defined using lithographic alignment marks.