Abstract-Terahertz quantum cascade laser based optical coherence tomography

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1656377

Alan W. M. Lee ; Tsung-Yu Kao ; Qing Hu ; John L. Reno

[+-] Author Affiliations

Proc. SPIE 8585, Terahertz and Ultrashort Electromagnetic Pulses for Biomedical Applications, 858508 (February 23, 2013); doi:10.1117/12.2001127

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. Due to 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 x 1 m with the source operated in a compact, closed-cycle cryocooler.© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).