A new generation of mid-infrared sensors based on Quantum Cascade Laser

Dibyendu Dey*, John Kohoutek, Ryan M. Gelfand, Alireza Bonakder, Hooman Mohseni

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


Many important bio and chemical molecules have their signature frequency (vibrational resonance) matching the mid infrared region (2-10 μm) of the optical spectrum. But building a bio-sensor, sensitive in this spectral regime, is extremely challenging task. It is because of the weak light-particle interaction strength due to huge dimensional mismatch between the probed molecules (typically ∼ 10's of nm) and the probing wavelength (order of micron). We exploit the optical antenna to overcome this problem by squeezing the optical modes. This modal confinement happens only in the near-field region of the antenna and thus we have built an apertureless near-field scanning optical microscope (a-NSOM) to demonstrate it experimentally. Further, we have integrated these plasmonic antennas with mid-infrared sources known as Quantum Cascade Lasers (QCL). Our antenna structure is based on metal-dielectric-metal (MDM) and we have shown how they can generate higher electrical field enhancement compared to single metal design. Antenna integrated QCL operated at room temperature and its wavelength of operation was measured to be ∼ 6um. We have used 3D finite-difference-time-domain (FDTD) simulations to optimize the different component of the MDM antenna. After optimizing, we fabricated the antenna on the facet of QCL using focused ion beam (FIB) and measured using a-NSOM. We have shown that the optical mode can be squeezed down to a few 100's of nm which is much smaller than the incident light wavelength (λ∼6μm). We also propose a microfluidic approach to build a typical mid-infrared bio-sensor where the probed molecules can be transferred to the near field region of the antenna through fluidic channels. Such scheme of building bio-sensor can overcome the barrier of weak light-particle interaction and eventually could lead to building very efficient, compact, mid-infrared bio-sensors.

Original languageEnglish (US)
Title of host publicationPhotonic Microdevices/Microstructures for Sensing III
StatePublished - Jul 25 2011
EventPhotonic Microdevices/Microstructures for Sensing III - Orlando, FL, United States
Duration: Apr 27 2011Apr 28 2011


OtherPhotonic Microdevices/Microstructures for Sensing III
Country/TerritoryUnited States
CityOrlando, FL


  • Bio-sensing
  • Field enhancement
  • Focused ion beam milling
  • Micro-fluidics
  • Near-field imaging
  • Optical antenna
  • Plasmonics
  • Quantum Cascade Laser
  • Surface plasmon resonance

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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