Microstrip-antenna-coupled distributed feedback terahertz quantum-cascade lasers

Tsung-Yu Kao; Xiaowei Cai; Qing Hu; John L. Reno

doi:10.1117/12.2036604

31 January 2014 Microstrip-antenna-coupled distributed feedback terahertz quantum-cascade lasers

Tsung-Yu Kao, Xiaowei Cai, Qing Hu, John L. Reno

Proceedings Volume 8993, Quantum Sensing and Nanophotonic Devices XI; 89930E (2014) https://doi.org/10.1117/12.2036604
Event: SPIE OPTO, 2014, San Francisco, California, United States

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.

Citation Download Citation

Tsung-Yu Kao, Xiaowei Cai, Qing Hu, and John L. Reno "Microstrip-antenna-coupled distributed feedback terahertz quantum-cascade lasers", Proc. SPIE 8993, Quantum Sensing and Nanophotonic Devices XI, 89930E (31 January 2014); https://doi.org/10.1117/12.2036604

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