Semiconductor Quantum Devices for Optical Tomography

Krikor B Ozanyan

Department of Electrical Engineering and Electronics, UMIST, PO Box 88, Manchester, M60 1QD, UK

ABSTRACT

This review examines recent developments in low-dimensional semiconductor devices and their impact on modalities for Optical Tomography. The current state-of-the-art in semiconductor optoelectronic materials is taken as basis to show that the design of multi-layer quantum devices can span a much wider functionality range than has been possible in the past. The basic principles of design and operation of some quantum optoelectronic devices are outlined, with emphasis on achievable flexibility to match the specific needs in the area of optical monitoring. It is shown, that opportunities to engineer required essential properties, such as spectral tunability of laser diode emission and spectral sensitivity of photoreceivers, are superior for quantum devices.

Two detailed examples are given in the mid-IR spectral range, the quantum-cascade laser (QCL) and the quantum-well infrared photodetector (QWIP). Their application to modalities for mid-IR gas monitoring is reviewed. It is argued that despite the functionality of those two devices being substantially different, future achievements in the performance of both will be largely sensitive to breakthroughs in one and the same field, e.g. the growth technology of quantum structures.

Keywords Optical, optoelectronic, laser diode, semiconductor photodetector