CONNECTING THE COMPOUND SEMICONDUCTOR COMMUNITY
April/May 2010 Volume 16 Number 3
Editor-in-Chief
David Ridsdale
+44 (0)1923 690210
Consultant Editor
Richard Stevenson PhD
richardstevenson@angelbc.co.uk
+44 (0)1291 629640
News Editor
Dr.Su Westwater
suwestwater@angelbc.co.uk
Director of SOLAR & IC Publishing
Jackie Cannon
+44 (0)1923 690205
Account Managers
Shehzad Munshi
+44 (0)1923 690215 Tommy Beazley
+44 (0)1923 690222
USA Representatives
Brun Media Tom Brun
Tel: 724 539-2404
Janice Jenkins E:
jjenkins@brunmedia.com Tel: 724-929-3550
Director of Logistics
Sharon Cowley
+44 (0)1923 690200
Design & Production Manager
Mitchell Gaynor
+44 (0)1923 690214
Circulation Director
Jan Smoothy
+44 (0)1923 690200
Subscriptions Manager
Debbie Higham
+44 (0)1923 690220
Chief Operating Officer
Stephen Whitehurst
stephen@angelbc.co.uk +44 (0)2476 718970
Directors
Bill Dunlop Uprichard – CEO Stephen Whitehurst – COO Jan Smoothy – CFO Haroon Malik, Jackie Cannon, Scott Adams, Sharon Cowley, Sukhi Bhadal
Published by
Angel Business Communications Ltd, Hannay House, 39 Clarendon Road, Watford, Herts WD17 1JA, UK T: +44 (0)1923 690200 F: +44 (0)1923 690201
Angel Business Communications Ltd Unit 6, Bow Court, Fletchworth Gate, Burnsall Road,Coventry CV5 6SP T: +44 (0)2476 718 970 F: +44 (0)2476 718 971
Compound Semiconductor is published eight times a year on a controlled circulation basis. Non-qualifying individuals can subscribe at: £105.00/€158 pa (UK & Europe), £138.00 pa (air mail), $198 pa (USA). Cover price £4.50. All information herein is believed to be correct at time of going to press. The publisher does not accept responsibility for any errors and omissions. The views expressed in this publication are not necessarily those of the publisher. Every effort has been made to obtain copyright permission for the material contained in this publication. Angel Business Communications Ltd will be happy to acknowledge any copyright oversights in a subsequent issue of the publication.
Angel Business Communications Ltd © Copyright 2010. All rights reserved. Contents may not be reproduced in whole or part without the written consent of the publishers.The paper used within this magazine is produced by chain of custody certified manufacturers, guaranteeing sustainable sourcing.
US mailing information: Compound Semiconductor (ISSN 1096-598X) is published 8 times a year Jan/Feb, March, April/May, June, July,August/September, October, November/December for a subscription of $198 by Angel Business Communications Ltd, Hannay House, 39 Clarendon Road,Watford, Herts WD17 1JA, UK. Periodicals postage paid at Rahway, NJ. POSTMASTER: send address changes to: Compound Semiconductor, c/o Mercury International Ltd, 365 Blair Road,Avenel, NJ 07001
Printed by: Pensord Press. ISSN 1096-598X
dh@angelbcl.co.uk
If powerful enough, easy-to-use and affordable quantum cascade lasers were available, then these sources would have a great chance of finding application in detecting gases, distracting heat-seeking missiles and aiding the construction of terahertz imaging systems. But for many years this class of laser, which was invented in the mid-1990s, has produced relatively feeble powers and been caged in a cryostat. But now the tide is turning …
In the Fall of 2008, this magazine covered the effort of Manijeh Razeghi’s group at Northwestern University, which had realized continuous-wave outputs of more than one tenth of a Watt at room temperature.
Back then these researchers were starting to look at new devices geometries, such as those that incorporating a buried ridge. Initial efforts showed that refinements such as that could lead to outputs of several Watts. However, at that time of writing the output was multi-mode - no good for gas sensing.
More recently, the US firm Pranalytica has produced quantum cascade lasers that deliver several Watts at room temperature via single-mode emission. This advance has come through a radical change in the structure of the laser: a change in the way that phonons are used to help to drive electrons to their lowest energy level within the laser.
Like Razeghi and her co-workers, the team at Pranalytica have detailed their efforts in an exclusive feature for Compound Semiconductor. If you want to read about the details of this new type quantum cascade structure, and the performance that it has realized, you can find their feature on p. 22.
Richard Stevenson PhD Consultant Editor
js@angelbcl.co.uk mg@angelbcl.co.uk sc@angelbcl.co.uk
The quantum cascade laser represents the pinnacle of bandgap engineering. By controlling of the thickness and composition of hundreds of very thin layers, engineers are able to tweak the wavefunctions of the electrons and holes that skitter through this structure, and ultimately fine-tune its emission.
Thanks to this control, quantum cascade lasers can span a range of wavelengths that are outside the grasp of their more conventional, III-V cousins. This includes vast swathes of the infrared spectrum with energies that can be used to probe the absorption lines of various gases, and far longer wavelengths close to a terahertz.
E:
tbrun@brunmedia.com
sm@angelbcl.co.uk tb@angelbcl.co.uk
jc@angelbcl.co.uk
Quantum cascade lasers shake off the R&D tag
dr@angelbcl.co.uk
editorialview
April/May 2010
www.compoundsemiconductor.net 3
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232 |
Page 233 |
Page 234 |
Page 235 |
Page 236 |
Page 237 |
Page 238 |
Page 239 |
Page 240 |
Page 241 |
Page 242 |
Page 243 |
Page 244 |
Page 245 |
Page 246 |
Page 247 |
Page 248 |
Page 249 |
Page 250 |
Page 251 |
Page 252 |
Page 253 |
Page 254 |
Page 255 |
Page 256 |
Page 257 |
Page 258 |
Page 259 |
Page 260 |
Page 261 |
Page 262 |
Page 263 |
Page 264 |
Page 265 |
Page 266 |
Page 267 |
Page 268 |
Page 269 |
Page 270 |
Page 271 |
Page 272