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Puscasu, I., & Boreman, G. D. (2001). Theoretical and experimental analysis of transmission and enchanced absorption of frequency selective surfaces in the infrared. In Proc. SPIE (Vol. 4293, pp. 185–190).
Abstract: A comparative study between theory and experiment is presented for transmission through lossy frequency selective surfaces (FSSs) on silicon in the 2 – 15 micrometer range. Important parameters controlling the resonance shape and location are identified: dipole length, spacing, impedance, and dielectric surroundings. Their separate influence is exhibited. The primary resonance mechanism of FSSs is the resonance of the individual metallic patches. There is no discernable resonance arising from a feed-coupled configuration. The real part of the element's impedance controls the minimum value of transmission, while scarcely affecting its location. Varying the imaginary part shifts the location of resonance, while only slightly changing the minimum value of transmission. With such fine-tuning, it is possible to make a good fit between theory and experiment near the dipole resonance on any sample. A fixed choice of impedance can provide a reasonable fit to all samples fabricated under the same conditions. The dielectric surroundings change the resonance wavelength of the FSS compared to its value in air. The presence of FSS on the substrate increases the absorptivity/emissivity of the surface in a resonant way. Such enhancement is shown for dipole and cross arrays at several wavelengths.
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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.
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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.
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González, F. J., & Boreman, G. D. (2005). Comparison of dipole, bowtie, spiral and log-periodic IR antennas. Inf Phys & Technol, 46(5), 418–428.
Abstract: Antenna-coupled microbolometers use planar lithographic antennas to couple infrared radiation into a bolometer with sub-micron dimensions. In this paper four different types of infrared antennas were fabricated on thin grounded-substrates and coupled to microbolometers. Dipole, bowtie, spiral and log-periodic IR antenna-coupled detectors were measured at 10.6 μm and their performance compared. A new method to calculate the radiation efficiency based on the spatial and angular response of infrared antennas is presented and used to evaluate their performance. The calculated radiation efficiency for the dipole, bowtie, spiral and log-periodic IR antennas was 20%, 37%, 25% and 46% respectively. A dipole-length study was performed and shows that the quasistatic value of the effective permittivity accurately describes the incident wavelength in the substrate at infrared frequencies for antennas on a thin substrate.
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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.
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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.
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Novotny, L. (2007). Effective wavelength scaling for optical antennas. Phys. Rev. Lett., 98(26), 266802(1–4).
Abstract: In antenna theory, antenna parameters are directly related to the wavelength λ of incident radiation, but this scaling fails at optical frequencies where metals behave as strongly coupled plasmas. In this Letter we show that antenna designs can be transferred to the optical frequency regime by replacing λ by a linearly scaled effective wavelength λeff=n1+n2λ/λp, with λp being the plasma wavelength and n1, n2 being coefficients that depend on geometry and material properties. It is assumed that the antenna is made of linear segments with radii Râ‰<aa>λ. Optical antennas hold great promise for increasing the efficiency of photovoltaics, light-emitting devices, and optical sensors.
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Gonzalez, F. J., Ilic, B., Alda, J., & Boreman, G. D. (2005). Antenna-coupled infrared detectors for imaging applications. IEEE J. Sel. Topics Quantum Electron., 11(1), 117–120.
Abstract: Infrared focal plane arrays (IRFPAs) are a critical component in advanced infrared imaging systems. IRFPAs are made up of two parts, a detector array and a readout integrated circuit (ROIC) multiplexer. Current ROIC technology has typical pitch sizes of 20×20 to 50×50 μm2. In order to make antenna-coupled detectors suited for infrared imaging systems, two-dimensional (2-D) arrays have been fabricated that cover a whole pixel area with the penalty of increasing the noise figure of the detector and, therefore, reducing its performance. By coupling a Fresnel zone plate lens to a single element antenna-coupled detector, infrared radiation can be collected over a typical pixel area and still keep low-noise levels. A Fresnel zone plate lens coupled to a single-element square-spiral-coupled infrared detector has been fabricated and its performance compared to single element antenna-coupled detectors and 2-D arrays of antenna coupled detectors. Measurements made at 10.6 μm showed a two-order-of-magnitude increase in SNR and a ~× increase in D* as compared to 2-D arrays of antenna-coupled detectors.
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Hocker, L. O., Sokoloff, D. R., Daneu, V., Szoke, A., & Javan, A. (1968). Frequency mixing in the infrared and far-infrared using a metal-to-metal point contact diode. Appl Phys Lett, 12(12).
Abstract: Metalâ€toâ€metal point contact diodes were used to obtain the 54â€GHz beat notes between two adjacent 10.6â€μ CO2 laser transitions. The speed of the diodes in the farâ€infrared is at least 1000 GHz. This was tested with a 337â€μ HCN laser.
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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.
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