Abstract

The terahertz frequency range of the electromagnetic spectrum has a broad number of potential applications across the physical, medical and biological sciences. Yet its full potential has historically not been realized owing to the lack of compact, solid state, sources and detectors.

The demonstration in 2002 of the first terahertz frequency quantum cascade laser opened up a plethora of new opportunities, with sources now capable of delivering output powers exceeding 1 W. I will outline how photonic patterning can be used to select specific frequencies and control output beam profiles, and how the laser gain can be probed by, and the laser locked with, near-infrared femtosecond laser technologies. I will then discuss the development of self-mixing imaging systems, which use the quantum cascade laser itself as a coherent detector, enabling: reflection imaging at distances exceeding 7 m; the demonstration of swept-frequency interferometry; and, coherent three-dimensional imaging. The talk will conclude by outlining the potential of terahertz quantum cascade lasers for use as local oscillators in satellite-based instrumentation for earth observation and planetary science, and the application of terahertz frequency instrumentation in the study of both condensed matter and biological systems.