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Proceedings Paper

Microstrip-antenna-coupled distributed feedback terahertz quantum-cascade lasers
Author(s): Tsung-Yu Kao; Xiaowei Cai; Qing Hu; John L. Reno
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Paper Abstract

By introducing coupled microstrip antennas on THz Distributed Feedback (DFB) Quantum Cascade Lasers (QCLs), the radiation efficiency of each feedback aperture is greatly enhanced. Single mode emission ~3 THz from a 31-period antenna-coupled third-order DFB laser yields ~4 times improvement in output power comparing with a corrugated thirdorder device fabricated on the same gain medium. This 31-period device has ~15×25° beam divergence and 4 mW pulsed power (4%) at 10 K with maximum lasing temperature (Tmax) at 134 K (pulsed). When phase matching condition is met, emissions from 81 apertures (4-mm long) are coherently combined to form a narrow beam with 12.5° divergence. Further experiment demonstrated the new device at 4 THz (25-period, ~18 μm×1-mm long. The 4 THz device reaches >8 mW pulsed power (10%) at 12 K with Tmax 109 K (pulsed) and >77 K (cw). The slope efficiency is 450 mW/A with 0.57% wall-plug. It is worth pointing out although the antennas would be excited differently, similar enhancement in out-coupling efficiency can also be observed in second-order surface-emitting THz DFB lasers. Begin the abstract two lines below author names and addresses.

Paper Details

Date Published: 31 January 2014
PDF: 9 pages
Proc. SPIE 8993, Quantum Sensing and Nanophotonic Devices XI, 89930E (31 January 2014); doi: 10.1117/12.2036604
Show Author Affiliations
Tsung-Yu Kao, Massachusetts Institute of Technology (United States)
Xiaowei Cai, Massachusetts Institute of Technology (United States)
Qing Hu, Massachusetts Institute of Technology (United States)
John L. Reno, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 8993:
Quantum Sensing and Nanophotonic Devices XI
Manijeh Razeghi; Eric Tournié; Gail J. Brown, Editor(s)

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