Terahertz tomography using quantum-cascade lasers
Author(s)Kao, Tsung-Yu; Hu, Qing; Reno, John L.; Lee, Alan; Burghoff, David Patrick
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The interfaces of a dielectric sample are resolved in reflection geometry using light from a frequency agile array of terahertz quantum-cascade lasers. The terahertz source is a 10-element linear array of third-order distributed-feedback QCLs emitting at discrete frequencies from 2.08 to 2.4 THz. Emission from the array is collimated and sent through a Michelson interferometer, with the sample placed in one of the arms. Interference signals collected at each frequency are used to reconstruct an interferogram and detect the interfaces in the sample. Because of the long coherence length of the source, the interferometer arms need not be adjusted to the zero-path delay. A depth resolution of 360 µm in the dielectric is achieved with further potential improvement through improved frequency coverage of the array. The entire experiment footprint is < 1 m × 1 m with the source operated in a compact, closed-cycle cryocooler.
DepartmentMassachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Optical Society of America
Wei Min Lee, Alan, Tsung-Yu Kao, David Burghoff, Qing Hu, and John L. Reno. “Terahertz Tomography Using Quantum-Cascade Lasers.” Optics Letters 37, no. 2 (January 15, 2012): 217. © 2012 Optical Society of America
Final published version