Sat, 26 Jul 2008 04:21:15 BST CiteULike: Author Yablonovitch http://www.citeulike.org/author/Yablonovitch CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/JeremyZucker/article/3016111 <i>Solar Energy Materials, Vol. 21, No. 2-3. (December 1990), pp. 99-111.</i><br /><br />Much work has been done over the past 10 years on the concentration of solar radiation using a variety of devices. To concentrate the light, photons from a larger area are collected and directed to a smaller area. Some devices use geometrical optics, or a change in index of refraction to increase the illumination on a surface above the incident solar level. Other systems use a frequency or Stokes shift to increase the illumination of light at one photon energy at the expense of another. There is often confusion as to the concentration limit imposed by basic physical laws on these different types of systems. Presented is a unification of the ideas and principles developed for the various classifications of concentrators. Equations are developed that describe the limits of concentration in geometrical and fluorescent systems. Concentration is shown to be a function of the index of refraction, angular collection range, as well as the frequency shift. Applications of the ideas involve the understanding of diffuse radiation concentrators and the solar powered laser. The thermodynamic limits of light concentrators G Smestad H Ries R Winston E Yablonovitch doi:10.1016/0165-1633(90)90047-5 Solar Energy Materials, Vol. 21, No. 2-3. (December 1990), pp. 99-111. 2008-07-18T01:48:26-00:00 1990 Solar Energy Materials 21 2-3 99 111 solar-power http://www.citeulike.org/user/rice/article/2911995 <i>Physical Review Letters, Vol. 57, No. 2. (14 July 1986), 249.</i> Unusually Low Surface-Recombination Velocity on Silicon and Germanium Surfaces E Yablonovitch DL Allara CC Chang T Gmitter TB Bright doi:10.1103/PhysRevLett.57.249 Physical Review Letters, Vol. 57, No. 2. (14 July 1986), 249. 2008-06-21T04:30:47-00:00 1986 Physical Review Letters 57 2 249 American Physical Society physrev http://www.citeulike.org/group/5283/article/925318 <i>Physical Review Letters, Vol. 67, No. 24. (December 1991), 3380.</i><br /><br />Three-dimensionally periodic dielectric structures; photonic crystals; possessing a forbidden gap for electromagnetic wave propagation; a photonic band gap; are now known. If the perfect 3D periodicity is broken by a local defect; local electromagnetic modes can occur within the forbidden band gap. Addition of extra dielectric material locally; inside the photonic crystal; produces ââdonorââ modes. Conversely; local removal of dielectric material from the crystal produces ââacceptorââ modes. It is now possible to make high- Q electromagnetic cavities of â¼1 cubic wavelength; for short wavelengths at which metallic cavities are useless. These new dielectric cavities can cover the range from mm waves to UV wavelengths. Donor and acceptor modes in photonic band structure E Yablonovitch TJ Gmitter RD Meade AM Rappe KD Brommer JD Joannopoulos doi:10.1103/PhysRevLett.67.3380 Physical Review Letters, Vol. 67, No. 24. (December 1991), 3380. 2006-11-02T11:23:02-00:00 1991 Physical Review Letters 67 24 3380 American Physical Society crystal photonic http://www.citeulike.org/user/dcastro/article/2776197 <i>Antennas and Propagation, IEEE Transactions on, Vol. 53, No. 4. (2005), pp. 1377-1381.</i><br /><br />The high-impedance surface was used as the antenna ground plane between two radiator elements to reduce the inter-element coupling between them. Measurement reveals the optimum performance occurred at the bandgap due to the suppression of surface currents in the ground plane. An application of high-impedance ground planes to phased array antennas RFJ Broas DF Sievenpiper E Yablonovitch doi:10.1109/TAP.2005.844408 Antennas and Propagation, IEEE Transactions on, Vol. 53, No. 4. (2005), pp. 1377-1381. 2008-05-09T15:46:49-00:00 2005 Antennas and Propagation, IEEE Transactions on 53 4 1377 1381 antenna array high impedance pbg phased http://www.citeulike.org/user/dcastro/article/2774520 <i>Radio and Wireless Conference, 1998. RAWCON 98. 1998 IEEE (1998), pp. 221-224.</i><br /><br />The microstrip patch is one of the most preferred antenna structures for low-cost and compact design of wireless communication systems and RF sensors. To overcome several intrinsic limitations of the patch antenna such as narrow bandwidth, low gain, and degradation of radiation efficiency at higher frequencies, we propose a novel technique for gain and bandwidth enhancement based on the photonic band-gap (PBG) concept. The Ku-band prototype demonstrates over 3 times bandwidth improvement, and 1.6 dB higher gain or 45% increase in effective radiated power (ERP), compared with a regular patch with identical dimensions. System design issues such as co-site interference can also be alleviated by the improved beam patterns of the new PBG antenna A novel approach for gain and bandwidth enhancement of patch antennas Yongxi Qian D Sievenpiper V Radisic E Yablonovitch T Itoh doi:10.1109/RAWCON.1998.709176 Radio and Wireless Conference, 1998. RAWCON 98. 1998 IEEE (1998), pp. 221-224. 2008-05-09T06:44:33-00:00 1998 Radio and Wireless Conference, 1998. RAWCON 98. 1998 IEEE 221 224 active antenna bandwidth gain patch http://www.citeulike.org/user/dhbradshaw/article/2675284 <i>Physical Review Letters, Vol. 80, No. 13. (30 March 1998), 2829.</i> 3D Metallo-Dielectric Photonic Crystals with Strong Capacitive Coupling between Metallic Islands DF Sievenpiper E Yablonovitch JN Winn S Fan PR Villeneuve JD Joannopoulos doi:10.1103/PhysRevLett.80.2829 Physical Review Letters, Vol. 80, No. 13. (30 March 1998), 2829. 2008-04-15T20:15:26-00:00 1998 Physical Review Letters 80 13 2829 American Physical Society no-tag http://www.citeulike.org/user/dhbradshaw/article/2582938 <i>Physical Review Letters, Vol. 62, No. 15. (10 April 1989), 1742.</i><br /><br />Shortly after Hawking’s prediction of thermal radiation from black holes; it became apparent that observers in accelerating frames should see a Planck distribution of electromagnetic radiation (Unruh radiation). Since an acceleration g =980 cm/sec 2 produces a radiation temperature of only ∼4×10 -20 K; the detection of such thermal radiation is a major challenge. A nonlinear optical medium whose index of refraction is changing rapidly with time accelerates zero-point quantum fluctuations. The sudden ionization of a gas or a semiconductor crystal to generate a plasma on a subpicosecond time scale can produce a reference frame accelerating at ∼10 20 g relative to an inertial frame. Accelerating reference frame for electromagnetic waves in a rapidly growing plasma: Unruh-Davies-Fulling-DeWitt radiation and the nonadiabatic Casimir effect E Yablonovitch doi:10.1103/PhysRevLett.62.1742 Physical Review Letters, Vol. 62, No. 15. (10 April 1989), 1742. 2008-03-24T22:41:57-00:00 1989 Physical Review Letters 62 15 1742 American Physical Society adiabatic http://www.citeulike.org/user/dhbradshaw/article/2516717 <i>Physical Review Letters, Vol. 61, No. 22. (28 November 1988), 2546.</i><br /><br />Inhibited spontaneous emission in atomic physics has been intensively investigated recently. In solid-state physics these effects are no less important. We have studied the spontaneous emission of light from electron-hole recombination in optically thin GaAs double heterostructures. The electron-hole radiative recombination rate coefficient B is not purely a property of the GaAs itself; but depends strongly on the optical-mode density and refractive index of the medium in which it is immersed. The spontaneous-emission rate can be markedly increased or decreased depending on whether the surrounding refractive index is higher or lower than that of GaAs. Inhibited and Enhanced Spontaneous Emission from Optically Thin AlGaAs/GaAs Double Heterostructures E Yablonovitch TJ Gmitter R Bhat doi:10.1103/PhysRevLett.61.2546 Physical Review Letters, Vol. 61, No. 22. (28 November 1988), 2546. 2008-03-11T21:30:28-00:00 1988 Physical Review Letters 61 22 2546 American Physical Society no-tag http://www.citeulike.org/user/ijbuss/article/1807181 <i>Opt. Lett., Vol. 8, No. 9. (1983), 491.</i> Maximum statistical increase of optical absorption in textured semiconductor films HW Deckman CB Roxlo E Yablonovitch Opt. Lett., Vol. 8, No. 9. (1983), 491. 2007-10-22T16:20:36-00:00 1983 Opt. Lett. 8 9 491 OSA roughness http://www.citeulike.org/user/ijbuss/article/1807053 <i>Applied Physics Letters, Vol. 75, No. 8. (1999), pp. 1036-1038.</i><br /><br />We describe a promising thin-slab light-emitting diode (LED) design, which uses a highly efficient coherent external scattering of trapped light by a two-dimensional (2D) photonic crystal. The light generation region was an unpatterned heterostructure surrounded by the light extraction region, a thin film patterned as a 2D photonic crystal. A six-fold photoluminescence enhancement was observed compared to an unpatterned thin film LED. That corresponded to 70% external quantum efficiency. ©1999 American Institute of Physics. Light extraction from optically pumped light-emitting diode by thin-slab photonic crystals M Boroditsky TF Krauss R Coccioli R Vrijen R Bhat E Yablonovitch doi:10.1063/1.124588 Applied Physics Letters, Vol. 75, No. 8. (1999), pp. 1036-1038. 2007-10-22T15:43:12-00:00 1999 Applied Physics Letters 75 8 1036 1038 AIP crystal led outcoupling photonic http://www.citeulike.org/user/yaronk/article/1466745 <i>Optoelectronics, IEE Proceedings -, Vol. 145, No. 6. (1998), pp. 391-397.</i><br /><br />In photonic crystals, electromagnetic waves can be confined in all three dimensions leading to very small mode volumes. Computational search has been for smallest electromagnetic mode which occurs in two-dimensional dielectric photonic crystals slabs. The smallest mode volume found was V&ap;2(λ/2n)³, where n is the refractive index. This small mode volume can lead to significant enhancement of spontaneous emission rates in semiconductor nano-cavities due to the Purcell effect Smallest possible electromagnetic mode volume in a dielectric cavity R Coccioli M Boroditsky KW Kim Y Rahmat-Samii E Yablonovitch Optoelectronics, IEE Proceedings -, Vol. 145, No. 6. (1998), pp. 391-397. 2007-07-19T07:51:14-00:00 1998 Optoelectronics, IEE Proceedings - 145 6 391 397 microcavities http://www.citeulike.org/user/mawulf/article/682919 <i>Physical Review Letters, Vol. 58, No. 20. (1987), pp. 2059-2062.</i><br /><br />It has been recognized for some time that the spontaneous emission of atoms is not necessarily a fixed and immutable property of the coupling between matter and space, but that it can be controlled by modification of the properties of the radiation field. This is equally true in the solid state, where spontaneous emission plays a fundamental role in limiting the performance of semiconductor lasers, heterojunction bipolar transistors. and solar cells. If a three dimensionally periodic dielectric structure has an electromagnetic band gap which overlaps the electronic band edge then spontaneous emission can be rigorously forbidden. Inhibited spontaneous emission in solid-state physics and electronics Eli Yablonovitch doi:10.1103/PhysRevLett.58.2059 Physical Review Letters, Vol. 58, No. 20. (1987), pp. 2059-2062. 2006-06-03T18:59:52-00:00 1987 Physical Review Letters 58 20 2059 2062 APS photonic-crystals http://www.citeulike.org/user/jrw/article/271900 <i>(30 Jul 2005)</i><br /><br />Electrometers measure electric charge, but there must be a fundamental speed limit to measuring one electric charge. Since there are no dimensional inputs to this question, the answer must be expressible in terms of the fundamental physical constants of Nature, e,h,m,c. In general the question should be posed without reference to any specific technology, but for definiteness, we analyze the field effect transistor, which is essentially an electrometer. In spite of selecting a specific technology, we find that the speed limit is related to a fundamental constant, the Rydberg frequency, or as appropriate, the semiconductor Rydberg frequency including the electron effective mass, and the relative dielectric constant. We do not know whether the Rydberg frequency represents the upper speed limit, but on dimensional grounds we claim that the final limit can only differ by some power of the fine-structure-constant. What is the Fastest Speed at which a Single Electron Can Be Detected? Deepak Rao Thomas Szkopek Hongwen Jiang Eli Yablonovitch (30 Jul 2005) 2005-08-02T18:58:17-00:00 2005 physics quantum