Dr Joshua Freeman

Profile

Joshua Freeman completed an MPhys 4-year degree in Physics at the University of Oxford. He then moved to the University of Cambridge where he studied for a PhD in the Semiconductor Physics Group of the Cavendish Laboratory. The main focus of his PhD was on the design, fabrication and characterisation of heterogeneous active regions in THz quantum cascade lasers (QCLs).

After completing his PhD, he started a post-doctoral Fellowship in the Cavendish Laboratory with the support of a departmental PhD-Plus award. During this time, he continued to pursue the research themes of his PhD, designing, fabricating and studying broadband active regions in THz QCLs. 

In 2011 won an individual intra-European fellowship and took up the Marie Curie position at the Ecole Normale Supérieure in Paris. The fellowship proposal centred on the modelocking of QCLs and their coherent detection. After this he returned to the UK to take up a post-doctoral research fellowship at the University of Leeds working on coherent detection of THz QCLs operating in ‘continuous-wave’.

In April 2016, he was awarded a ‘University Academic Fellowship’ at the University of Leeds. This is a structured five year fellowship development programme leading to an Associate Professor role.

Research interests

Josh is actively researching many aspects of terahertz technology fundamentals and applications. These include many aspects of quantum cascade laser active region design and the physical dynamics that govern these unipolar semiconductor lasers; the development of high power quantum cascade lasers and high precision control of these lasers; the dynamics of QCLs, studied using ultra-fast THz time-domain spectroscopy techniques to gain a great understanding of the important time scales these device; and phase-locking of QCLs to other terahertz sources.

He is also interested in the applications of THz radiation to science and industry, particularly applications to solid-state materials. He collaborates nationally and internationally on these projects with groups at University of Cambridge, University College London, London Centre for Nanotechnoloy, Delft, Ecole Normale Supérieure Paris, and others.

Student education

• Personal Tutor
• Module leader ELEC1701
• Level 1 tutor

Research groups and institutes

• Pollard Institute
• Terahertz electronics and photonics

Current postgraduate researchers

• Yifan Weng
• Nick Surtees
• Ben Muggleton

Projects

<li><a href="//phd.leeds.ac.uk/project/2124-electrical-injection-of-thz-spin-excitations-in-topological-solid-state-devices">Electrical injection of THz spin excitations in topological solid state devices</a></li>