Terahertz frequency detection and identification of materials and objects: [proceedings of the NATO Advanced Research Workshop on Terahertz Frequency Detection and Identification of Materials and Objects, Spiez, Switzerland, 7 - 11 July 2006]

Terahertz frequency sensing has a unique part to play in the detection and identification of materials and objects. This frequency range, corresponding to a wavelength of around 0.1 mm, can be used to identify materials from their molecular spectra and to produce images of concealed objects. Terahertz spectra of drugs of abuse and explosives presented by a number of the contributing authors show that the presence of these materials can be detected in envelopes, packages and through clothing. The technology of terahertz detection has largely been developed around expensive and bulky femtosecond laser systems but, as described in this book, advances in semiconductor superlattice technology are leading to compact “electronic” sources such as the quantum cascade laser, two-terminal “Gunn” type oscillators and even a THz frequency amplifier. These advances towards electronic (as opposed to optical) THz systems mean that the technology will become portable and much less costly. Terahertz remote sensing is also discussed with the possibility of detection over distances of up to 30m using existing technology or even through the use THz waves generated locally in the vicinity of a target using only air as the transducer. This book contains contributions from world leaders in terahertz science and technology and is complemented by comments and assessments from industry and security experts. Contents......Page 6 Organising Committee......Page 9 Sponsors......Page 10 Preface......Page 11 Theme 1: Devices......Page 12 Terahertz Emission from Semiconductors Excited by Ultrafast Laser Pulses......Page 13 Terahertz Generation by Multiplication......Page 27 Towards Superlattice Terahertz Amplifiers and Lasers......Page 41 Tailoring the Emission of Terahertz Quantum Cascade Lasers......Page 51 Guided Propagation of Terahertz Pulses on Metal Wires......Page 65 Superlattice and Other Negative-Differential-Resistance Devices: Current Status......Page 79 Theme 2: Interactions with Materials......Page 99 Molecular and Organic Interactions......Page 100 Terahertz Beam Interactions with Amorphous Materials......Page 116 Development of Tagless Biosensors for Detecting the Presence of Pathogens......Page 132 Theme 3: Detection and Sensing......Page 144 Improvements to Electronic Techniques for Terahertz Spectroscopic Detection......Page 145 Terahertz Time-Domain Spectroscopy of Crystalline and Aqueous Systems......Page 154 Continuous-Wave Terahertz Photomixer Systems for Real-World Applications......Page 173 Theme 4: Systems for Security......Page 191 Systems Requirements for A Multi-Channel Terahertz Contraband Scanner......Page 192 Challenges to Terahertz Counter-Terrorism and Security-Related Applications......Page 210 Terahertz Detection of Illegal Objects......Page 230 Terahertz Rays to Detect Drugs of Abuse......Page 246 Terahertz Spectroscopy for Explosive, Pharmaceutical, and Biological Sensing Applications......Page 256 Terahertz Communications: A 2020 vision......Page 329 Theme 5: Overview......Page 343 Applied Terahertz Science: The Technology of the Future, and Always Will Be?......Page 344 List of speakers......Page 356 List of participants......Page 358 Group photograph......Page 359 C......Page 360 H......Page 361 N......Page 362 S......Page 363 T......Page 364 Z......Page 365 Annotation Want an overview of where the technology of terahertz detection has been going? Here it is. The technology has largely been developed around expensive and bulky femtosecond laser systems but, as described in this book, advances in semiconductor superlattice technology are leading to compact 'electronic' sources such as the quantum cascade laser, two-terminal 'Gunn' type oscillators and even a THz frequency amplifier. These advances towards electronic (as opposed to optical) THz systems mean that the technology will become portable and much less costly