A Breakthrough In Developing Multi-Watt Terahertz Lasers
Arthur T Knackerbracket has found the following story:
Terahertz lasers could soon have their moment. Emitting radiation that sits somewhere between microwaves and infrared light along the electromagnetic spectrum, terahertz lasers have been the focus of intense study due to their ability to penetrate common packaging materials such as plastics, fabrics, and cardboard and be used for identification and detection of various chemicals and biomolecular species, and even for imaging of some types of biological tissue without causing damage. Fulfilling terahertz lasers' potential for us hinges on improving their intensity and brightness, achieved by enhancing power output and beam quality.
Sushil Kumar, associate professor in Lehigh University's Department of Electrical and Computer Engineering, and his research team are working at the forefront of terahertz semiconductor 'quantum-cascade' laser (QCL) technology. In 2018, Kumar, who is also affiliated with Lehigh's Center for Photonics and Nanoelectronics (CPN) reported on a simple yet effective technique to enhance the power output of single-mode lasers based on a new type of "distributed-feedback" mechanism.
[...] Now, Kumar, Jin and John L. Reno of Sandia are reporting another terahertz technology breakthrough: they have developed a new phase-locking technique for plasmonic lasers and, through its use, achieved a record-high power output for terahertz lasers. Their laser produced the highest radiative efficiency for any single-wavelength semiconductor quantum cascade laser. These results are explained in a paper, "Phase-locked terahertz plasmonic laser array with 2 W output power in a single spectral mode" published yesterday in Optica.
"To the best of our knowledge, the radiative efficiency of our terahertz lasers is the highest demonstrated for any single-wavelength QCL to-date and is the first report of a radiative efficiency of greater than 50% achieved in such QCLs," said Kumar. "Such a high radiative efficiency beat our expectations, and it is also one of the reasons why the output power from our laser is significantly greater than what has been achieved previously."
More information: Yuan Jin et al, Phase-locked terahertz plasmonic laser array with 2 W output power in a single spectral mode, Optica (2020). DOI: 10.1364/OPTICA.390852
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