Details of Grant 

EPSRC Reference:	GR/R84962/01
Title:	Terahertz Sideband Generation and Quantum Coherence studies in Quantum Cascade Lasers
Principal Investigator:	Phillips, Professor C
Other Investigators:
Researcher Co-Investigators:
Project Partners:	Thomson Csf-Lcr Vienna University of Technology
Department:	Physics
Organisation:	Imperial College London
Scheme:	Standard Research (Pre-FEC)
Starts:	01 September 2002	Ends:	28 February 2006	Value (£):	285,634
EPSRC Research Topic Classifications:	Lasers & Optics Materials Characterisation
EPSRC Industrial Sector Classifications:	Communications Electronics
Related Grants:	GR/R84955/01
Panel History:
Summary on Grant Application Form
Following successful trial spectroscopic experiments with a free-electron-laser we propose a new opto-electronic device in which the resonant interaction between the intra-cavity mid-IR radiation field inside a quantum cascade laser and a second near IR beam is used to produce coherent sidebands which correspond to the FM and AM modulation of the near-IR beam at THz rates. There is a close analogue with RF heterodyning techniques for wavelength modulation/ demodulation. The effect will be demonstrated in a simple 2-terminal device for the first tme, and the limits and critical factors determining the ultimate conversion efficiency will be established.By studying the resonance behaviour of the conversion efficiency, we will use the effect as a unique spectroscopic probe of the electronic and photonic states in the QCL, as it is actually operating. Because the intracavity radiation density is high and the coupling to so-called intersubband transitions is so strong exotic quantum-optical effects, such as electromagnetically-induced-transparency will become observable for the first time in an operating laser. Because these and other dressed state effects break the classical assumptions made in Einstein's arguments for population inversion for lasers, they offer a route to genuine inversionless lasing (LWI) of a type previously only seen in atomic vapours, as well as promising a host of other non-Einsteinian coherent phenomena of interest to the quantum-computing communities. This will enable, for the first time, major progress towards CW 300K QCL device operation for gas sensing and environmental monitoring applications..
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Organisation Website:	http://www.imperial.ac.uk