Active Optical Antennas

Summary Background Optical antennas are single or coupled metallic nanoparticles in which optical excitation of surface plasmons can produce very high intensities in the optical near field. The field enhancement relative to the incident field is maximum when the wavelength is suitably matched to the size of the resonant nanoparticle. Of particular interest are resonant optical antennas comprised of a pair of strongly coupled metallic nanorods. This design leads to a large intensity enhancement localized in the gap between the latter.

Invention The invention is a photonic device which consists of a resonant optical antenna integrated on the facet of a commercial diode laser. This device generates enhanced and spatially confined optical near fields. Spot sizes of a few tens of nanometers have been measured at a wavelength ~0.8 µm. In addition, the device can be implemented in a wide variety of semiconductor lasers emitting in spectral regions ranging from the visible to the far infrared, including quantum cascade lasers.

One implementation of the invention uses a bowtie antenna of length comparable to the surface plasmon wavelength, aligned along the direction of the laser polarization. This allows a strong concentration of the electric field in the gap of the antenna. A cross optical antenna will produce even higher intensities due to its better coupling to the near field. All antennas are fabricated on a thin dielectric layer directly deposited on the facet by standard methods in order to avoid electrical shorting of the laser.

Such a compact laser source with subwavelength spatial resolution provides distinct advantages in a number of applications including microscopy, spectroscopy, optical data storage, lithography, and laser processing and heat-assisted magnetic recording.

Reference: "Plasmonic Laser Antenna," Ertugrul Cubukcu, Eric A. Kort, Kenneth B. Crozier, Federico Capasso, Applied Physics Letters, vol. 89, pp. 093120 (2006)

Patent Status: Pending

Applications Microscopy; spectroscopy; optical data storage; lithography; laser processing. For Further Information Please Contact the Director of Business Development Alan Gordon Email: alan_gordon@harvard.edu Telephone: (617) 384-5000

Inventor(s): Capasso, Federico

Type of Offer: Licensing



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