Plasmonic Laser Antennas and Related Devices

• Published in: IEEE journal of selected topics in quantum electronics 2008-11, Vol.14 (6), p.1448-1461
• Main Authors: Cubukcu, E., Nanfang Yu, Smythe, E.J., Diehl, L., Crozier, K.B., Capasso, F.
• Format: Article
• Language: English
• Subjects: Antennas; Devices; Glass; Glass substrates; Gold; Gold nanoparticles; Lasers; Nanocomposites; Nanomaterials; Nanostructure; near-field optics; Optical devices; Optical microscopy; Optical surface waves; Plasmonics; Plasmons; Resonance; Silicon compounds; Spectroscopy; Spectrum analysis; Substrates; surface plasmons (SPs); surface-enhanced Raman spectroscopy (SERS); Wavelengths
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2007.912747

This paper reviews recent work on device applications of optical antennas. Localized surface plasmon resonances of gold nanorod antennas resting on a silica glass substrate were modeled by finite difference time-domain simulations. A single gold nanorod of length 150 or 550 nm resonantly generates enhanced near fields when illuminated with light of 830 nm wavelength. A pair of these nanorods gives higher field enhancements due to capacitive coupling between them. Bowtie antennas that consist of a pair of triangular gold particles offer the best near-field confinement and enhancement. Plasmonic laser antennas based on the coupled nanorod antenna design were fabricated by focused ion beam lithography on the facet of a semiconductor laser diode operating at a wavelength of 830 nm. An optical spot size of few tens of nanometers was measured by apertureless near-field optical microscope. We have extended our work on plasmonic antenna into mid-infrared (mid-IR) wavelengths by implementing resonant nanorod and bowtie antennas on the facets of various quantum cascade lasers. Experiments show that this mid-IR device can provide an optical intensity confinement 70 times higher than that would be achieved with diffraction limited optics. Near-field intensities ~ 1 GW/cm 2 were estimated for both near-infrared and mid-IR plasmonic antennas. A fiber device that takes advantage of plasmonic resonances of gold nanorod arrays providing a high density of optical ldquohot spotsrdquo is proposed. Results of a systematic theoretical and experimental study of the reflection spectra of these arrays fabricated on a silica glass substrate are also presented. The family of these proof-of-concept plasmonic devices that we present here can be potentially useful in many applications including near-field optical microscopes, high-density optical data storage, surface enhanced Raman spectroscopy, heat-assisted magnetic recording, and spatially resolved absorption spectroscopy.