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Multimode, Aperiodic Terahertz Surface-Emitting Laser Resonators

NEST, CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK
Author to whom correspondence should be addressed.
Photonics 2016, 3(2), 32;
Received: 5 April 2016 / Revised: 13 May 2016 / Accepted: 16 May 2016 / Published: 20 May 2016
(This article belongs to the Special Issue Quantum Cascade Lasers - Advances and New Applications)
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Quasi-crystal structures are conventionally built following deterministic generation rules although they do not present a full spatial periodicity. If used as laser resonators, they open up intriguing design possibilities that are simply not possible in conventional periodic photonic crystals: the distinction between symmetric (vertically radiative but low quality factor Q) and anti-symmetric (non-radiative, high Q) modes is indeed here fully overcome, offering a concrete perspective of highly efficient vertical emitting resonators. We here exploit electrically pumped terahertz quantum cascade heterostructures to devise two-dimensional seven-fold quasi-crystal resonators, exploiting rotational order or irregularly distributed defects. By lithographically tuning the lattice quasi-periodicity and/or the hole radius of the imprinted patterns, efficient multimode surface emission with a rich sequence of spectral lines distributed over a 2.9–3.4 THz bandwidth was reached. We demonstrated multicolor emission with 67 mW of peak optical power, slope efficiencies up to ≈70 mW/A, 0.14% wall plug efficiencies and beam profile results of the rich quasi-crystal Fourier spectrum that, in the case of larger rotational order, can reach very low divergence. View Full-Text
Keywords: Terahertz; quantum cascade lasers; quasi-crystals Terahertz; quantum cascade lasers; quasi-crystals

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Biasco, S.; Li, L.; Linfield, E.H.; Davies, A.G.; Vitiello, M.S. Multimode, Aperiodic Terahertz Surface-Emitting Laser Resonators. Photonics 2016, 3, 32.

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