Professor John Cunningham

Responsibilities

• Director of Research and Innovation
• Director of the UK Network for THz Science and Technology Teranet

Research interests

My research is on the development of high frequency (megahertz to terahertz) electronic / photonic techniques for the interrogation and manipulation of a wide range of systems

A major theme has been the development of on-chip terahertz systems, which provide a versatile way to confine THz radiation to length-scales far below the diffraction limit of free-space propagating THz radiation.  In these systems, pulses of THz radiation are generated using an ultrafast laser, and are then guided through lithographically defined waveguides, where they interact with either samples or devices, before being detected.  Since the size of these systems is limited only by lithographic considerations, they are ideally suited to study the THz response of individual mesoscopic systems and nanostructures, for example. We have used this technique to develop many spectroscopy, imaging, and sensing applications, including (but not limited to) the low temperature THz spectroscopy of polycrystalline chemicals, the modulation and detection of plasmons and magnetoplasmons in 2D electron gases, and the scanned imaging of semiconductors.  We are now extending the technique to endoscopy and detection of cancerous tumours.

A second theme of my work is the development of new applications for high frequency (MHz to 10's GHz) surface acoustic waves (SAWs).  SAW filters find commercial application as delay lines in mobile phones, but we use SAWs as a way to provide a high frequency perturbation to micro- and nano-structures.  The piezoelectric potential which accompanies the mechanical movement of a SAW can be used to push charge through semiconducting materials - the so-called acoustoelectric transport.  We demonstrated this effect in graphene for the first time. We have also demonstrated the mechanical alignment and transport of micron scale particles in microfluidic systems mediated by SAWs, and are currently researching the interaction of SAWs with magnetic systems to move both magnetic domain walls and skyrmions, with possible applications in low energy computing.

Another recent application for high frequency acoustic waves we are studying is using them to perturb (and ultimately control) the light output from terahertz quantum cascade lasers.   THz QCLs offer the potential for high data rate communications in both terrestrial and satellite applications, with the picosecond relaxation times in principle enabling modulation rates exceeding 100 GHz.  We are interested in how acoustic waves interact with carriers in these quantum systems, and how they could be used to introduce a controllable local perturbation to the bandstructure, both from a fundamental point of view and as a method for modulation with a view to fast communication schemes.

Much of the above work makes use of our extensive cleanroom fabrication facilities, which include electron beam lithography, while experiments are undertaken in our world-class high frequency and THz photonics laboratories.  Our facilities include Ti:sapphire lasers, and a range of cryostats able to access low temperatures alongside providing up to THz frequency range excitation and detection capabilities.

I am always interested in hearing from potential collaborators and PhD students.  If you have ideas for new collaborative projects, or would like to discuss potential PhD topics in related areas, please send me an email.

• Acoustic control of quantum cascade heterostructures: the THz "S-LASER"

Research groups and institutes

• Pollard Institute
• Terahertz electronics and photonics
• Bio-nanoelectronics

Current postgraduate researchers

• Jintao Shuai
• Luke Benson

Projects

<li><a href="//phd.leeds.ac.uk/project/1161-terahertz-photonics">Terahertz Photonics</a></li>