Fig. 1. (a) Surface plasmon polariton at single interface. (b) Localized surface plasma resonance for subwavelength metal nanoparticles. Figures reproduced from: (a) ref. ²⁶, Nature Publishing Group; (b) ref. ²⁷, Springer International Publishing AG.

Fig. 2. Basic optical detection mechanism in semiconductors. (a) Intrinsic absorption (interband transition), (b) Free carrier absorption, (c) Extrinsic absorption (impurity transition).

Fig. 3. Different plasmonic structures. (a) Grating structure. (b) Two-dimensional hole array structure. (c) Nanorods inserted in absorber. (d) Nanoparticle. (e) Nanopyramids. (f) Micropatch. Figures reproduced from: (a) ref. 28, Macmillan Publishers Limited; (b) ref. ³¹, AIP Publishing; (c) ref. ³³, American Chemical Society; (d) ref. ³⁴, Journal of Mechanical Engineering; (e) ref. ³⁵, Optical Society of America.

Fig. 4. Plasmonic 2DSHA-hetero n-i-p photodetector. (a) Schematic diagram of the device. (b) Spectra of electric field enhancement in 2DSHA with a period of 900 nm at the hot spot position, as indicated in the inset. (c) Room-temperature responsivity. (d) Room-temperature blackbody detectivity. Figures reproduced from: ref. ³⁰, AIP Publishing.

Fig. 5. Plasmonic 2DSHA-hetero n-InAsSb/n-GaSb photodetector. (a) Schematic diagram of the device. (b) Photocurrent spectral measured at room temperature. Figures reproduced from: (a) ref. ⁴⁰, Springer Science+Business Media New York; (b) ref. ³⁸.

Fig. 6. Schematic diagrams of plasmonic Schottky detectors. A gold patch on p-Si substrate with a gold grating on top. Figures reproduced from ref. ²⁹, Optical Society of America.

Fig. 7. Schematic diagrams of plasmonic photoconductive detectors. (a) Antenna assisted graphene detector. (b) MSM plasmonic waveguide with Ge as absorber and Au as plasmonic cladding. Figures reproduced from: (a) ref. ⁴⁶, American Chemical Society; (b) ref. ⁴⁸, American Chemical Society.

Fig. 8. Schematic diagrams of plasmonic quantum type detectors. (a) 2DSHA gold structure fabricated on the Ge/Si QDIP. (b) Au nanoantenna embedded in the QD layer on SiO₂ substrate. (c) Plasmonic nano-disk arrays on QDIP. (d) Plasmonic hole array patterned on top of the DWELL detector. Figures reproduced from: (a) ref. ³¹, AIP Publishing; (b) ref. ⁵³, AIP Publishing; (c) ref. ⁵⁴, The Royal Society of Chemistry; (d) ref. ⁵⁶, Macmillan Publishers Limited.

Fig. 9. Schematic diagrams of plasmonic thermal detectors. (a) A gold 2DSHA structure on top of ZnO pyroelectric layer. (b) A unit cell of the plasmonic absorber consisting of symmetrical gold split cross resonator. Figures reproduced from: (a) ref. ⁵⁹, American Chemical Society; (b) ref. ⁶⁰, Optical Society of America.

Fig. 10. Schematic diagrams of plasmonic detectors. (a) Scanning electron microscope (SEM) image of the detector integrated with plasmonic patch resonator array. (b) SEM image of the CNT detector with plasmonic electrodes. Figure reproduced from: (a) ref. ⁶¹, Macmillan Publishers Limited; (b) ref. ⁶², American Chemical Society.