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 journalArticlepeer-review

19 Scopus citations

Abstract

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
Volume18
Issue number12
DOIs
StatePublished - Dec 12 2018

Bibliographical note

Funding Information:
This work was supported primarilyby the National Science Foundation (NSF Award No. ECCS 1809240 to M.L. and S.-H.O., ECCS-1708768 to C.C. and M.L., and ECCS-1610333 to D.A.M. H.-K.C., and S.-H.O.). C.C. and M.L. also acknowledge support from the Office of Naval Research (ONR) through a MURI grant N00014-17-1-2661.D.A.M. and S.-H.O. also acknowledge support from Seagate through the MINT consortium at the University of Minnesota. S.-H.O. further acknowledges the Sanford P. Bordeau Endowed Chair in Electrical Engineering at the University of Minnesota.Device fabrication was carried out at the Minnesota Nanofabrication Center, which receives partial support from the NSF through the National Nanotechnology Coordinated Infrastructure (NNCI) program. The authors also used resources at the Characterization Facility, which is a member of the NSF-funded Materials Research Facilities Network via the NSF MRSEC program.

Funding Information:
We thank Dr. Huan Li for the helpful discussion on the coupled mode theory. This work was supported primarily by the National Science Foundation (NSF Award No. ECCS 1809240 to M.L. and S.-H.O., ECCS-1708768 to C.C. and M.L., and ECCS-1610333 to D.A.M., H.-K.C., and S.-H.O.). C.C. and M.L. also acknowledge support from the Office of Naval Research (ONR) through a MURI grant N00014-17-1-2661. D.A.M. and S.-H.O. also acknowledge support from Seagate through the MINT consortium at the University of Minnesota. S.-H.O. further acknowledges the Sanford P. Bordeau Endowed Chair in Electrical Engineering at the University of Minnesota. Device fabrication was carried out at the Minnesota Nanofabrication Center, which receives partial support from the NSF through the National Nanotechnology Coordinated Infrastructure (NNCI) program. The authors also used resources at the Characterization Facility, which is a member of the NSF-funded Materials Research Facilities Network via the NSF MRSEC program.

Keywords

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

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