Program and Abstract Book - SRON

More documents

Recommendations

Info

19 th International Symposium on Space Terahertz Technology 11-3 Short GaAs/AlAs superlattices as THz radiation sources D.G. Paveliev, Yu.I. Koschurinov Radiophysics Department, Nizhny Novgorod State University, Russia V.M. Ustinov, A.E. Zhukov Ioffe Physico-Technical Institute,St.Petersburg,Russia F. Lewen, C. Endres I.Physikalisches Institut, Universität zu Köln, Germany A.M. Baryshev SRON Netherlands Institute for Space Research and Kapteyn Astromomical Institute, University of Groningen, Netherlands K.F. Renk, B.I. Stahl Institut für Angewandte Physik, Universität Regensburg, Germany Semi-conductor devices based on diodes with Schottky barrier are widely used in room temperature applications in the THz frequency range. However, application of Schottky barrier diodes in these frequencies is limited by several factors: long time of carrier passage through the barrier and relatively large specific capacity. Shorter times of the response and a smaller value of the specific capacity can be achieved by creation of the diodes on the basis of semiconductor superlattices. The superlattice for diodes (length 112 nm) with 18 periods was grown by using molecular beam technology. Each period (length 6.22 nm) has 18 monolayers GaAs and 4 monolayers AlAs, and is homogeneously doped with silicon (2×10 18 cm -3 ). The minibandwidth of 25 meV was sufficient to lead to miniband rather than hopping transport behaviour. For these diodes we have also minimized values of series resistance R s and parasitic capacity C par of a substrate carrying the diode. The area of the active region of the diode was less than 2х10 -8 cm 2 . Measurement results of the output power level, efficiency and output harmonics content at room temperature are shown for the devices based on the new planar superlattice diodes for input frequency ranges 10-20 GHz, 78-118 GHz and 180-240 GHz. In this report the superlattice device applications as THz radiation sources are discussed. 94
19 th International Symposium on Space Terahertz Technology 11-4 A new experimental procedure for determining the response of bolometric detectors to fields in any state of coherence Cristopher Thomas and Stafford Withington Detector and Optical Physics Group, Cavendish Laboratory, University of Cambridge, JJ Thompson Avenue, Cambridge, CB3 0HE, UK Any bolometer that is greater than a few wavelengths in size is receptive to the power in a number of fully coherent optical modes simultaneously. Knowing the amplitude, phase, and polarisation patterns of these modes, and their relative sensitivities, is central to being able to use a multimode detector effectively. We describe a procedure for measuring the full spatial state of coherence to which a detector is sensitive. Diagonalisation of the coherence function then gives the natural modes. The scheme is based on the result that the expectation value of the output of any detector, or indeed whole instrument or telescope, is given by the contraction of two tensor fields, one of which describes the state of coherence of the incoming radiation, and the other describes the state of coherence of the field to which the detector is sensitive. It follows that if a detector is illuminated by two coherent point sources, in the near or far field, and the phase of one source rotated relative to the other, the output of the detector displays a fringe. By repeating the process with different source locations, the entire detector coherence tensor can be reconstructed from the recorded complex visibilities. This new, powerful technique is essentially aperture synthesis interferometry in reverse, and therefore many data processing techniques developed in the context of astronomy can be used for measuring the optical modes of bolometers. 95
Page 1 and 2:
ISSTT 2008 19 th International Symp
Page 3 and 4:
19 th International Symposium on Sp
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46: 19 th International Symposium on Sp
Page 95: 19 th International Symposium on Sp
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
show all

Program and Abstract Book - SRON

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?