@inproceedings{57a47333f014469b99a5ec5b05ee7978,
title = "THz quantum cascade lasers for operation above cryogenic temperatures",
abstract = "High temperature operation of terahertz (THz) sources based on quantum cascade lasers (QCLs) is discussed. THz QCLs are compact, powerful sources but can only operate at cryogenic temperatures. State-of-the art THz QCLs are made with GaAs/AlGaAs heterostructures and use a single composition of AlGaAs for the barrier material. It was recently shown that multi-composition barriers in the band structure can result in gain > loss at temperature as high as ∼240K. We demonstrate early experimental results that yield QCLs that operate up to 184K - similar to QCLs based on single composition barrier designs. An alternative method of producing room-temperature THz is based on intra-cavity difference-frequency generation (DFG) in mid-infrared (mid-IR) QCLs. Here we report devices with record conversion efficiency. THz DFG QCLs reported previously are highly inefficient since THz radiation produced more than ∼100 μm away from the exit facet is fully absorbed due to high THz losses in the QCL waveguide. Our lasers use a non-collinear Cherenkov DFG scheme to extract THz radiation from the active region. Dual-color mid-IR quantum cascade lasers with integrated giant optical nonlinearity are grown on semi-insulating (S.I.) InP substrates. THz radiation is emitted at an angle into the substrate with respect to the mid-infrared pumps. Since S.I. InP is virtually lossless to THz radiation, this scheme allows for efficient extraction of THz radiation along the whole waveguide length. As a result, our sources demonstrate large mid-infrared-to-THz conversion efficiency. Devices tested at room-temperature produced 18μW peakpower and 75μW/W2 conversion efficiency.",
keywords = "Difference frequency generation, Terahertz quantum cascade laser, Terahertz sources",
author = "Belkin, {M. A.} and K. Vijayraghavan and A. Vizbaras and A. Jiang and F. Demmerle and G. Boehm and R. Meyer and Amann, {M. C.} and A. Matyas and R. Chashmahcharagh and P. Lugli and C. Jirauschek and Wasilewski, {Z. R.}",
year = "2013",
doi = "10.1117/12.2000858",
language = "English",
isbn = "9780819494092",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
booktitle = "Novel In-Plane Semiconductor Lasers XII",
note = "Novel In-Plane Semiconductor Lasers XII ; Conference date: 04-02-2013 Through 07-02-2013",
}