Waveguide-Integrated Compact Plasmonic Resonators for On-Chip Mid-Infrared Laser Spectroscopy

Che Chen, Daniel A. Mohr, Han Kyu Choi, Daehan Yoo, Mo Li, Sang Hyun Oh

Research output: Contribution to journalArticle

15 Scopus citations


The integration of nanoplasmonic devices with a silicon photonic platform affords a new approach for efficient light delivery by combining the high field enhancement of plasmonics and the ultralow propagation loss of dielectric waveguides. Such a hybrid integration obviates the need for a bulky free-space optics setup and can lead to fully integrated, on-chip optical sensing systems. Here, we demonstrate ultracompact plasmonic resonators directly patterned atop a silicon waveguide for mid-infrared spectroscopic chemical sensing. The footprint of the plasmonic nanorod resonators is as small as 2 μm 2 , yet they can couple with the mid-infrared waveguide mode efficiently. The plasmonic resonance is directly measured through the transmission spectrum of the waveguide with a coupling efficiency greater than 70% and a field intensity enhancement factor of over 3600 relative to the evanescent waveguide field intensity. Using this hybrid device and a tunable mid-infrared laser source, surface-enhanced infrared absorption spectroscopy of both a thin poly(methyl methacrylate) film and an octadecanethiol monolayer is successfully demonstrated.

Original languageEnglish (US)
Pages (from-to)7601-7608
Number of pages8
JournalNano letters
Issue number12
StatePublished - Dec 12 2018


  • Plasmonics
  • nanogap
  • optical parametric oscillator (OPO)
  • silicon photonics
  • surface-enhanced infrared absorption (SEIRA)
  • waveguide

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