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González, F. J., Alda, J., Ilic, B., & Boreman, G. D. (2004). Infrared Antennas Coupled to Lithographic Fresnel Zone Plate Lenses. Appl. Opt., 43(33), 6067–6073.
Abstract: Several designs for Fresnel zone plate lenses (FZPLs) to be used in conjunction with antenna-coupled infrared detectors have been fabricated and tested. The designs comprise square and circular FZPLs with different numbers of Fresnel zones working in transmissive or reflective modes designed to focus infrared energy on a square-spiral antenna connected to a microbolometer. A 163× maximum increase in response was obtained from a 15-zone circular FZPL in the transmissive mode. Sensor measurements of normalized detectivity D* resulted in a 2.67× increase with FZPLs compared with measurements made of square-spiral antennas without FZPLs. The experimental results are discussed and compared with values obtained from theoretical calculations.
Keywords: optical antennas
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Boreman, G. D. (1997). Infrared microantennas. SPIE, 3110, 882–885.
Abstract: We present results of mesurments of the polarization response of asymetric spiral antennas coupled Ni-NiO-Ni diodes, over the wavelength range 10.2 to 10.7 μm. The feed structure of the antenna imposes an elliptical polarization singature that is different from the circular polarization expected from a symmetric spiral. We develop a lossy-transmission-line model yielding the measured polarization response. A combination of a balanced and an unbalanced mode is required. Reflected current waves from the arm ends are significant.
Keywords: optical antennas
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Codreanu, I., & Boreman, G. D. (2001). Infrared microstrip dipole antennas. Microw Opt Technol Lett, 29(6), 381–383.
Abstract: Abstract 10.1002/mop.1184.abs We report on the successful use of niobium microbolometers coupled to microstrip dipole antennas for the detection of midinfrared radiation. Measurements of the detector response versus antenna length performed at the 10.6 μm wavelength allowed us to identify the first three current-wave resonances along the antenna arms. The detector response was also measured as a function of the radiation wavelength in the 911 μm spectral domain. Excellent agreement between the experimental results and finite-difference time-domain (FDTD) predictions was obtained.
Keywords: optical antennas
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Bryant, G. W., García de Abajo, F. J., & Aizpurua, J. (2008). Mapping the Plasmon Resonances of Metallic Nanoantennas. Nano Lett., 5(2), 631–636.
Abstract: We study the light scattering and surface plasmon resonances of Au nanorods that are commonly used as optical nanoantennas in analogy to dipole radio antennas for chemical and biodetection field-enhanced spectroscopies and scanned-probe microscopies. With the use of the boundary element method, we calculate the nanorod near-field and far-field response to show how the nanorod shape and dimensions determine its optical response. A full mapping of the size (length and radius) dependence for Au nanorods is obtained. The dipolar plasmon resonance wavelength λ shows a nearly linear dependence on total rod length L out to the largest lengths that we study. However, L is always substantially less than λ/2, indicating the difference between optical nanoantennas and long-wavelength traditional λ/2 antennas. Although it is often assumed that the plasmon wavelength scales with the nanorod aspect ratio, we find that this scaling does not apply except in the extreme limit of very small, spherical nanoparticles. The plasmon response depends critically on both the rod length and radius. Large (500 nm) differences in resonance wavelength are found for structures with different sizes but with the same aspect ratio. In addition, the plasmon resonance deduced from the near-field enhancement can be significantly red-shifted due to retardation from the resonance in far-field scattering. Large differences in near-field and far-field response, together with the breakdown of the simple scaling law must be accounted for in the choice and design of metallic λ/2 nanoantennas. We provide a general, practical map of the resonances for use in locating the desired response for gold nanoantennas.
Keywords: optical antennas
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Tang, L., Kocabas, S. E., Latif, S., Okyay, A. K., Ly-Gagnon, D. - S., Saraswat, K. C., et al. (2008). Nanometre-scale germanium photodetector enhanced by a near-infrared dipole antenna. Nature Photonics, 2, 226–229.
Abstract: A critical challenge for the convergence of optics and electronics is that the micrometre scale of optics is significantly larger than the nanometre scale of modern electronic devices. In the conversion from photons to electrons by photodetectors, this size incompatibility often leads to substantial penalties in power dissipation, area, latency and noise. A photodetector can be made smaller by using a subwavelength active region; however, this can result in very low responsivity because of the diffraction limit of the light. Here we exploit the idea of a half-wave Hertz dipole antenna (length approx 380 nm) from radio waves, but at near-infrared wavelengths (length approx 1.3 microm), to concentrate radiation into a nanometre-scale germanium photodetector. This gives a polarization contrast of a factor of 20 in the resulting photocurrent in the subwavelength germanium element, which has an active volume of 0.00072 microm3, a size that is two orders of magnitude smaller than previously demonstrated detectors at such wavelengths.
Keywords: optical antennas
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Saynak, U. Ä. Ÿ. (2008). Novel rectangular spiral antennas.
Abstract: Round spiral antennas are generally designed by using Archimedean spiral geometries which have linear growth rates. To obtain smaller antennas with nearly the same performance, square spiral Archimedean geometries are also widely used instead. In this study, novel square antennas are proposed, designed and examined. At first two similar but different approaches are employed to design new antennas by considering the design procedure used to obtain log-periodic antennas. Then, the performance of these antennas is improved by considering another property of log-periodic antennas. Simulations are performed by using two different numerical methods which are Finite Difference Time Domain Method (FDTD) and Method of Moments (MoM). The results obtained from the simulations are compared with those of the Archimedean spiral antennas in terms of the frequency dependency of fundamental antenna parameters such as antenna gain and radiation pattern. The simulation results are compared with the ones obtained from the experimental study.
Keywords: optical antennas
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Heeres, R. W., Dorenbos, S. N., Koene, B., Solomon, G. S., Kouwenhoven, L. P., & Zwiller, V. (2010). On-Chip Single Plasmon Detection. Nano Lett., 10, 661–664.
Abstract: Surface plasmon polaritons (plasmons) have the potential to interface electronic and optical devices. They could prove extremely useful for integrated quantum information processing. Here we demonstrate on-chip electrical detection of single plasmons propagating along gold waveguides. The plasmons are excited using the single-photon emission of an optically emitting quantum dot. After propagating for several micrometers, the plasmons are coupled to a superconducting detector in the near-field. Correlation measurements prove that single plasmons are being detected.
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Bharadwaj, P., Deutsch, B., & Novotny, L. (2009). Optical Antennas. Adv. Opt. Photon, 1, 438–483.
Abstract: Optical antennas are an emerging concept in physical optics. Similar to radiowave
and microwave antennas, their purpose is to convert the energy of free propagating radiation to localized energy, and vice versa. Optical antennas exploit the unique properties of metal nanostructures, which behave as strongly coupled plasmas at ptical frequencies. The tutorial provides an account of the historical origins and the basic concepts and parameters associated with optical antennas. It also reviews recent work in the field and discusses areas of application, such as light-emitting devices, photovoltaics, and spectroscopy. Keywords: optical antennas
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Alda, J., Rico-García, J. M., López-Alonso, J. M., & Boreman, G. (2005). Optical antennas for nano-photonic applications. Nanotech., 16(5), S230–S234.
Abstract: Antenna-coupled optical detectors, also named optical antennas, are being developed and proposed as alternative detection devices for the millimetre, infrared, and visible spectra. Optical and infrared antennas represent a class of optical components that couple electromagnetic radiation in the visible and infrared wavelengths in the same way as radioelectric antennas do at the corresponding wavelengths. The size of optical antennas is in the range of the detected wavelength and they involve fabrication techniques with nanoscale spatial resolution. Optical antennas have already proved and potential advantages in the detection of light showing polarization dependence, tuneability, and rapid time response. They also can be considered as point detectors and directionally sensitive elements. So far, these detectors have been thoroughly tested in the mid-infrared with some positive results in the visible. The measurement and characterization of optical antennas requires the use of an experimental set-up with nanometric resolution. On the other hand, a computation simulation of the interaction between the material structures and the incoming electromagnetic radiation is needed to explore alternative designs of practical devices.
Keywords: optical antennas
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Huang, K. C. Y., Jun, Y. C., Seo, M. - K., & Brongersma, M. L. (2011). Power flow from a dipole emitter near an optical antenna. Opt. Express, 19(20), 19084–19092.
Abstract: Current methods to calculate the emission enhancement of a quantum emitter coupled to an optical antenna of arbitrary geometry rely on analyzing the total Poynting vector power flow out of the emitter or the dyadic Green functions from full-field numerical simulations. Unfortunately, these methods do not provide information regarding the nature of the dominant energy decay pathways. We present a new approach that allows for a rigorous separation, quantification, and visualization of the emitter output power flow captured by an antenna and the subsequent reradiation power flow to the far field. Such analysis reveals unprecedented details of the emitter/antenna coupling mechanisms and thus opens up new design strategies for strongly interacting emitter/antenna systems used in sensing, active plasmonics and metamaterials, and quantum optics.
Keywords: optical antennas
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