Stabilisation of 3.5 THz quantum-cascade laser local oscillators

Lead Organisations: University of Leeds
Project Lead: Alex Valavanis

Partners: STFC RAL Space

Advances in satellite remote-sensing measurements of the constituents of the atmosphere have substantially increased knowledge of atmospheric composition over the last decade. For instance, relatively localized studies of the mesosphere and lower thermosphere (MLT) region of the Earth’s atmosphere provide an important indicator of global climate change. Nonetheless, global measurements of key atmospheric species have not been made directly by previous satellite missions.

To address this limitation, a proposed UK satellite mission, LOCUS (Linking Observations of Climate, the Upper atmosphere and Space weather) will deploy a multi-channel radiometer operating in the terahertz (THz) spectral range (0.8–4.7 THz) in low Earth orbit and will allow global high spectral resolution measurements of important MLT atmospheric species, particularly atomic oxygen and the hydroxyl radical. Following the proposal of LOCUS for the 9th call of the ESA Earth Explorer programme, and the successful acceleration of its key payload technology through CEOI-ST support, the UK technical team now proposes to significantly enhance the stability and spectral resolution of the THz radiometers. This will raise the instrumentation technical maturity to a level compliant with future in-orbit-demonstration opportunities, and will place the UK in a position of scientific and technical leadership with respect to MLT climate studies.

The specific technical goal is to develop the first satellite-compatible (compact, integrated, robust and low-power) subsystem for stabilising the frequency of a compact 3.5 THz laser source, using a harmonic mixer based on Schottky diode technology, and coupling this to a local oscillator (LO).

The team will develop a precisely tunable 3.5 THz quantum-cascade laser (QCL), using a LO/mixer system to stabilise and control its emission frequency. The programme is extremely well matched to CEOI/UKSA/NSTP strategy. Moreover, it will deliver additional return through future application in a wider range of diverse disciplines including planetary science, astronomy, spectroscopy, security and communications.