Fig. 3

Basic configurations of NIR guided-wave nanophotonic biochemical sensors. a Interferometer: (i) schematic illustration of MZI biochemical sensor; (ii) microscopic image of MZI biochemical sensor array integrated with microfluidic channel (Reproduced with permission from [30]). b Microcavity resonator: (i) schematic illustration of MRR biochemical sensor integrated with microfluidic channel (Reproduced with permission from [31]); (ii) false-color SEM image of cascaded microdisk resonators on single bus waveguide (Reproduced with permission from [40]); (iii) SEM image of microtoroid resonator (Reproduced with permission from [19]). c Photonic crystal (PhC): (i) PhC nanobeam cavity biochemical sensor array (Reproduced with permission from [45]); (ii) SEM image of L3 PhC nanocavity accessed by W1 PhC waveguide (Reproduced with permission from [52]). d Bragg grating. Schematic illustrations of (i) Bragg grating; (ii) phase-shited Bragg grating. e Channel waveguide: (i) schematic illustration of methane absorption spectroscopy on a Si ridge waveguide (Reproduced with permission from [62]); (ii) integrated Si nanophotonic on-chip sensor (Reproduced with permission from [63])