.Department of Physics

Ultrafast Science Group

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Research interests: investigation of fundamental quantum processes in optically excited semiconductors using ultrafast optical techniques such as time domain THz spectroscopy, development of THz spectroscopic techniques and optoelectronic devices.

Group Members: Dr Steve Andrews, Mr Yi Pan, Miss Soumya Zangui, Mrs Siti

 Current research Projects:

THz time domain spectroscopy of semiconductor materials including quantum wells and two dimensional electron gases, development of THz devices such as detectors and waveguides and sensors based on metamaterials

 Facilities:

70 fs and 10 fs near infrared laser oscillators. Spectrometer for THz emission and transmission between 0.1 and 3.5 THz at temperatures down to 1.6 K and magnetic fields up to 7 T using photoconducting transmitters and receivers. Fiber coupled THz spectrometer for scattering measurements. 50 THz bandwidth spectrometer based on nonlinear optical few cycle generation and either photoconductive or electro-optic detection. Apparatus for standard cw measurements such as photoluminescence. Access to in-house nanofabrication laboratory for optical and e-beam lithography, deposition, reactive ion etching etc. LINK

Some THz publications :

‘Coherent control of cyclotron emission from a semiconductor using sub-picosecond electric field transients’ P G Huggard, J A Cluff, C J Shaw, S R Andrews, E H Linfield and D A Ritchie Appl. Phys. Lett. 71, 2647 (1997)

‘Magnetic field suppression of THz charge oscillations in a double quantum well’ S R Andrews, P G Huggard, C J Shaw, J A Cluff, O E Raichev and R Grey Phys. Rev B57, R9443 (1998)

‘Polarisation-dependent efficiency of photoconducting THz transmitters and receivers’ P G Huggard, C J Shaw, J A Cluff and S R Andrews Appl. Phys. Lett. 72, 2069 (1998)

‘THz emission from asymmetric double quantum wells’ S R Andrews, P G Huggard, C J Shaw, J A Cluff and R Grey in ‘Terahertz spectroscopy and applications II’ ed J M Chamberlain Proc SPIE Vol 3828, p244-253 (1999)

‘Mechanism of THz emission from coupled quantum wells’ P G Huggard, C J Shaw, S R Andrews, J A Cluff and R Grey Phys. Rev. Letts. 84, 1023-1026 (2000)

‘Drude conductivity of highly doped GaAs at terahertz frequencies’ P G Huggard, J A Cluff, G P Moore, C J Shaw, S R Andrews, S R Keiding, E H Linfield and D A Ritchie J Appl. Phys. 87, 2382-2385 (2000)

'Magnetic field dependence of THz emission from an optically excited GaAs p-i-n diode' S R Andrews, A Armitage, P GHuggard, C J Shaw and G P Moore Phys Rev. B66, 085307 (2002)

'Optimization of photoconducting receivers for THz spectroscopy' S R Andrews, A Armitage, P G Huggard and A Hussain Phys. Med. Biol. 47, 3705-3710 (2002)

 ‘Ultrafast Optical Excitation of Coherent Two-Dimensional Plasmons’ A Armitage, S R Andrews, J A Cluff, E H Linfield and D A Ritchie Phys Rev B 69, 125309 (2004)

‘Dynamic range of ultrabroadband terahertz detection using GaAs photoconductors’ A Hussain and S R Andrews, Appl. Phys. Lett. 88, 143514 (2006)

 ‘Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces ‘,  S A Maier and S R Andrews, Appl. Phys. Letts. 88, 251120 (2006)

 

 Previous group members: Dr Peter Huggard, Dr Adam Armitage, Dr Julian Cluff, Dr Graeme Moore, Chris Shaw

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