Terahertz frequency domain spectrometer with a single photoconductive element for terahertz signal generation and detection

摘要

There is described an apparatus for analyzing, identifying or imaging a target. The apparatus comprises a laser system which generates first and second laser beams having respective different frequencies, and directs the first and second laser beams along an optical path to a photoconductive material. An antenna structure is formed on the photoconductive material, the antenna structure comprises a first antenna for emitting electromagnetic radiation having a frequency dependent on the difference between said respective different frequencies of the first and second laser beams and a second antenna for generating a detection signal. A processor processes the detection signal to analyze, identify or image the target. The laser system is arranged such that the first and second laser beams overlap in a region of a surface of the photoconductive material having at least part of the first and second antennas formed thereon.

主权项

1. An apparatus for analyzing, identifying or imaging a target, the apparatus comprising:
a laser system operable to generate first and second laser beams having respective different frequencies, and to combine the first and second laser beams in an optical path; a photoconductive element provided in the optical path exposed to the combined first and second laser beams to emit electromagnetic radiation having a difference frequency dependent on a difference between said respective different frequencies of the first and second laser beams such that the electromagnetic radiation at the difference frequency is incident on the target which produces a return electromagnetic radiation that is co-incident on the photoconductive element with the combined first and second laser beams and detected by the photoconductive element to produce a detection signal such that a single photoconductive element produces (i) the difference frequency that is incident on the target as well as (ii) the detection signal responsive to the return electromagnetic radiation; and a processor for processing the detection signal to identify at least one characteristic of the target.