Fast terahertz imaging using a quantum cascade amplifier

A terahertz (THz) imaging scheme based on the effect of self-mixing in a 2.9 THz quantum cascade (QC) amplifier has been demonstrated. By coupling an antireflective-coated silicon lens to the facet of a QC laser, with no external optical feedback, the laser mirror losses are enhanced to fully suppre...

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Bibliographic Details
Published in:Applied physics letters 2015-07, Vol.107 (1)
Main Authors: Ren, Yuan, Wallis, Robert, Jessop, David Stephen, Degl'Innocenti, Riccardo, Klimont, Adam, Beere, Harvey E., Ritchie, David A.
Format: Article
Language:English
Subjects:
AMPLIFIERS
Applied physics
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
DATA ACQUISITION
ELECTRIC POTENTIAL
EMISSION
FEEDBACK
LASER MIRRORS
LASERS
Lasing
LENSES
LOSSES
Noise levels
Optical feedback
PEAKS
Photon density
PHOTONS
REFLECTION
SENSITIVITY
SIGNAL-TO-NOISE RATIO
SILICON
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Summary:A terahertz (THz) imaging scheme based on the effect of self-mixing in a 2.9 THz quantum cascade (QC) amplifier has been demonstrated. By coupling an antireflective-coated silicon lens to the facet of a QC laser, with no external optical feedback, the laser mirror losses are enhanced to fully suppress lasing action, creating a THz QC amplifier. The addition of reflection from an external target to the amplifier creates enough optical feedback to initiate lasing action and the resulting emission enhances photon-assisted transport, which in turn reduces the voltage across the device. At the peak gain point, the maximum photon density coupled back leads to a prominent self-mixing effect in the QC amplifier, leading to a high sensitivity, with a signal to noise ratio up to 55 dB, along with a fast data acquisition speed of 20 000 points per second.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4926602