Mechanically robust waveguide-integration and beam shaping of terahertz quantum cascade lasers

• Published in: Electronics letters Vol. 51; no. 12; pp. 919 - 921
• Main Authors: Valavanis, A, Han, Y.J, Brewster, N, Dean, P, Dong, R, Bushnell, L, Oldfield, M, Zhu, J.X, Li, L.H, Davies, A.G, Ellison, B, Linfield, E.H
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 11.06.2015
• Subjects: beam shaping; block integration scheme; copper; copper heat‐sink block; frequency 1 THz to 5 THz; heat sinks; mechanically robust waveguide‐integration; optical pulse shaping; Photonics; precision‐machined rectangular waveguide; quantum cascade lasers; rectangular waveguides; single‐lobed far‐field beam profile; terahertz wave devices; terahertz‐frequency quantum cascade lasers; threshold current; beam shaping; terahertz-frequency quantum cascade lasers; single-lobed far-field beam profile; heat sinks; threshold current; mechanically robust waveguide-integration; quantum cascade lasers; Cu; optical pulse shaping; block integration scheme; frequency 1 THz to 5 THz; terahertz wave devices; copper; rectangular waveguides; copper heat-sink block; precision-machined rectangular waveguide
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2015.1137

Terahertz-frequency quantum cascade lasers (THz QCLs) have numerous potential applications as 1–5 THz radiation sources in space science, biomedical and industrial sensing scenarios. However, the key obstacles to their wide-scale adoption outside laboratory environments have included their poor far-field beam quality and the lack of mechanically robust schemes that allow integration of QCLs with THz waveguides, mixers and other system components. A block integration scheme is presented, in which a continuous-wave ∼3.4 THz double-metal QCL is bonded into a precision-machined rectangular waveguide within a copper heat-sink block. This highly reproducible approach provides a single-lobed far-field beam profile with a divergence of ≲20°, and with no significant degradation in threshold current or in the range of operating temperatures.