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137750.2 |
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|a Kao, Tsung-Yu
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|a Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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|a Massachusetts Institute of Technology. Research Laboratory of Electronics
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|a Cai, Xiaowei
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|a Hu, Qing
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|a Reno, John L.
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|a Microstrip-antenna-coupled distributed feedback terahertz quantum-cascade lasers
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|b SPIE,
|c 2021-12-20T15:32:04Z.
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|z Get fulltext
|u https://hdl.handle.net/1721.1/137750.2
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|a 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 Tmax109 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.. © 2014 SPIE.
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|a Article
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|t 10.1117/12.2036604
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