(SP Wednesday Workshop) - Towards lower losses in THz Quantum Cascade Lasers

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• Mr Adam Klimont, University of Cambridge, Semiconductor Physics Group
• Wednesday 08 October 2014, 14:15-15:15
• Mott Seminar Room, Cavendish Laboratory, Department of Physics.

If you have a question about this talk, please contact Teri Bartlett.

Terahertz Quantum Cascade Lasers (QCLs) are complex heterostructure devices, where lasing action occurs between electronic levels in the conduction band only — in other words, they are unipolar lasers. The levels are carefully designed and carried out by growing hundreds of nanometre-thick GaAs/AlGaAs wells/barriers in an MBE chamber. The wafers are subsequently fabricated into 200μm ridges and embedded in an unusual “surface plasmon” waveguide — this is necessary in order to confine radiation in sub-wavelength dimensions, at the expense of high free carrier loss. After 10 years of development, QCLs remain one of the best THz sources: they are compact, tunable and reliable.

I will briefly describe the principle of operation of QCLs, their design and fabrication. Then I will move on to talk about loss mechanisms, which are a limiting factor in the temperature performance of the lasers. I will propose a way of reducing losses by changing the waveguide geometry; I will show preliminary simulation results and discuss fabrication challenges for the proposed design.

This talk is part of the Semiconductor Physics Group Seminars series.

This talk is included in these lists:

• All Cavendish Laboratory Seminars
• All Talks (aka the CURE list)
• Centre for Health Leadership and Enterprise
• Featured lists
• ME Seminar
• Mott Seminar Room, Cavendish Laboratory, Department of Physics
• Neurons, Fake News, DNA and your iPhone: The Mathematics of Information
• School of Physical Sciences
• Semiconductor Physics Group Seminars
• Thin Film Magnetic Talks

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