Portable Terahertz Systems Based on Advanced InP Technology - PORTRAIT

Lead Research Organisation: University of Leeds
Department Name: Electronic and Electrical Engineering

Abstract

This work is aimed at creating new types of portable sources and detectors of radiation. These will be handheld, about the size of a normal torch, and will run off batteries. They work in the terahertz (THz) range, this can be thought of either as very high frequency radio waves or as light which is invisible to the human eye. For a long time it has been quite difficult to generate and detect THz, but over recent years people have used large powerful lasers to create pulses of THz radiation. This has proved very useful in medical applications to build up pictures of body tissue, rather like an x-ray, which can show up abnormalities. Other interesting areas being studied include using THz in fossil imaging, analysing chemicals and gases, in security and in astronomy.The work in the project aims to make a new generation of THz 'torches' and 'cameras' which can be carried in the pocket. Making the devices, small, low power and portable, will allow people to use THz radiation in applications like airport security to screen for explosive chemicals or drugs, to look for pollution in the local environment, and even to be used in pharmacies or GPs for helping with diagnosis. Moreover the radiation they use will be very 'pure' and that will help to make very sensitive detection.A feature of the work is to build upon the optoelectronic technologies developed for optical communications systems which provides a good foundation of advanced fabrication techniques leading to high reliability components capable of low power and efficient room temperature operation. UCL, Bath and Essex will work together with the Centre for Integrated Photonics (CIP), to design, fabricate and characterise novel components for THz operation. Leeds will focus on users and applications issues undertaking a detailed comparison between the performances of old and new systems.
 
Description There are a large number of potential applications for terahertz spectroscopy and imaging systems. In the academic sector, these range from understanding the vibrational structures of crystalline materials, to probing the fundamental excitations in semiconductors and nanostructures. In the industrial sector, applications range from process monitoring in the pharmaceutical industry, through to non-destructive testing, security scanning, and medical engineering. Yet, traditionally, terahertz time-domain spectroscopy systems have used 800 nm Ti:sapphire laser-based technologies. Not only does this lead to higher system costs, but it also means that it is not possible to benefit from the wide range of components that are readily accessible at telecommunication wavelengths (around 1550 nm).

The 'PORTRAIT' grant, comprising a collaboration between the University of Essex (PI), University of Leeds, University College London, the University of Bath, and the Centre for Integrated Photonics (CIP, formally Corning, and now Huawei) aimed to address this and develop terahertz sources and detectors operating at 1550 nm wavelength. The Leeds programme focused on developing pulsed photoconductive emitters and receivers operating at 1550 nm, using Fe-doped InGaAs and InGaAsP grown by MOCVD at CIP. Detailed characterization was undertaken of the materials as a function of wavelength (750 - 1600 nm) using a Ti:sapphire pumped OPO system, and photoconductive switches structures were designed, fabricated and tested for use both as emitters and receivers. The performance matched, and indeed exceeded, that obtained using low-temperature-grown GaAs at 800 nm, opening up the possibility of developing and exploiting terahertz spectroscopy and imaging systems based on telecommunications-based technology. The results were jointly patented by the University of Leeds and CIP.
Exploitation Route The patented, demonstration of 1550 nm components for generation and detection of terahertz frequency radiation led to the immediate award of an EPSRC Follow-on Fund grant (EP/H029583) to develop commercialization opportunities, and the subsequent award of an EPSRC programme grant (COTS; EP/J017671) with UCL, the University of Cambridge and the London Centre for nanotechnology to develop coherent terahertz frequency systems. It also supported the award of an ERC Advanced Grant (TOSCA).
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics,Pharmaceuticals and Medical Biotechnology,Security and Diplomacy

 
Description H M Government Communications 
Organisation Her Majesty's Government Communications
Country United Kingdom 
Sector Public 
Start Year 2006
 
Description National Physical Laboratory 
Organisation National Physical Laboratory
Country United Kingdom 
Sector Academic/University 
Start Year 2006
 
Description Teraview Ltd 
Organisation Teraview Ltd
Country United Kingdom 
Sector Private 
Start Year 2006