Abstract
In the near field region, optical antennas can generate local hot spots with high energy density. It can be very useful in increasing the photon-matter interactions for bio-sensing applications. There are several important bio-molecules having signature frequency (vibrational resonance) matching the mid infrared region of the optical spectrum. Thus mid-infrared antenna integrated with Quantum cascade laser (QCL) is highly desirable as it is currently considered to be one of the most efficient mid-infrared laser sources with a huge gamut of commercial applications. Here, we present a novel metal-dielectric-metal (MDM) based plasmonic nanorod antenna integrated on the facet of a room temperature working Quantum Cascade Laser. Simulations showed that at an optimized SiO2 thickness of 20nm, the antenna can generate a local electric field with intensity 500 times higher than the incident field intensity. Further, it can increase the number of regions with local hot spots due to a higher number of geometrical singularities or sharp edges present in the MDM structure. This feature can be extremely useful, especially for bio-sensing applications. All device structures have been optimized based on 3d finite-difference timedomain (FDTD) numerical simulations. The antenna was fabricated on the facet of QCL using focused ion beam (FIB). The integrated plasmonic QCL has been measured using an apertureless mid-infrared near field scanning optical microscopy (a-NSOM). The measurement set-up is based on an inverted microscope coupled with a commercially available Atomic Forced Microscopy (AFM). We have experimentally found that such integrated nano antenna can generate a very narrow optical spot size, much below the diffraction limit, with high power density that matches well with the simulation results.
Original language | English (US) |
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Title of host publication | Laser Beam Shaping XI |
Volume | 7789 |
DOIs | |
State | Published - Oct 28 2010 |
Event | Laser Beam Shaping XI - San Diego, CA, United States Duration: Aug 2 2010 → Aug 2 2010 |
Other
Other | Laser Beam Shaping XI |
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Country | United States |
City | San Diego, CA |
Period | 8/2/10 → 8/2/10 |
Keywords
- Bio-sensing
- Field enhancement
- Focused ion beam milling
- 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