Enhanced Detection of Broadband Incoherent Light with Nanoridge Plasmonics

Emerging photonic integrated circuit technologies require integrative functionality at ultrahigh speed and dimensional compatibility with ultrasmall electronics. Plasmonics offers a promise of addressing these challenges with novel nanophotonic approaches for on-chip information processing or sensing applications. Short communication range and strong light-matter interaction enabled by on-chip plasmonics allow us to extend beyond a conventional approach of integrating coherent and narrowband light source. Such hybrid electronic and photonic interconnection desires a on-chip photodetector that is highly responsive to broadband incoherent light, yet provides elegant design for nanoscale integration. Here we demonstrate an ultracompact broadband photodetection with greatly enhanced photoresponsivity using plasmonic nanoridge geometry. The nanoridge photodetector confines a wide spectrum of electromagnetic energy in a nanostructure through the excitation of multiple plasmons, which thus enables the detection of weak and broadband light. With nanoscale design, material, and dimensional compatibility for the integration, the nanoridge photodetector opens up a new possibility of highly sensitive on-chip photodetection for future integrated circuits and sensing applications.