Aperiodic lattices for photonic engineering of terahertz quantum cascade lasers

Focussed Ion Beam lithography for achieving Tunable THz QCL

The University of Manchester (School of Electrical and Electronic Engineering) has been awarded over £0.5M from EPSRC and HMGCC to develop tunable terahertz quantum cascade lasers using aperiodic photonic lattices. Optical wavelength-scale photonic lattices (i.e. lattices formed from a spatially-varying refractive index) offer a very powerful mechanism to define and modify the photon resonance characteristics in a range of optical devices. Although highly successful up to now this approach has only been based on periodic lattices (with only a single, underlying spatial frequency and associated with only a single colour of light) and so does not provide the ability to control the colour of the confined photons. In this proposal, Dr S Chakraborty, PI of this grant, will apply aperiodic lattices (ALs) to a terahertz (THz) quantum cascade laser (QCL) to provide significantly advanced spectral functionalities, e.g. to give just one example, multi-coloured lasing at user-defined frequencies and to enable tunability. The demonstration of a compact, coherent, tunable THz QCL arising from this research will act as a significant enabler in the advancement of THz photonics and will sow the seeds for some commercially very significant THz technology. Recent years has seen THz technology (frequency: 1-10 THz, wavelength: 30-300 micron) the focus of much attention owing to its important impact in a wide range of commercial and security applications, for example, in medicine, microelectronics, security imaging, biotoxin detection, agriculture, gas sensing and environmental monitoring, and forensic science, etc. The development of the THz QCL has been a key development in the burgeoning of these technology areas. However, lack of THz QCL tunability has also acted as a major constraint.

 

Laboratory facilities include:

  • Bruker Vertex 80 Fourier Transform Infrared (FTIR) spectrometer, for collection of high resolution near-IR to THz spectra.
  • Janis ST‑100 continuous‑flow liquid‑He cryostat, for cryogenic electrical and optical device characterization.
  • Janis ST‑500 micro-manipulated cryogenic probe system, for cryogenic high‑frequency measurements.

For more information on the project, click on the links below:

 

Further Information and Application

Potential PhD students may wish to contact Dr Chakraborty for informal discussion on 0161 306 4831, or by e-mail s.chakraborty@manchester.ac.uk.

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