12 November 1999 Detection and time delay of a broadband rf signal using a traveling fringes detector
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Abstract
This paper presents an optical system which enables a broadband RF signal to be detected and delayed by a traveling fringes detector (TFD) using an acousto-optic deflector (AOD) and a 4f imaging system. The TFD is based upon the synchronous drift of photo-generated carriers with a moving interference pattern; the moving interference pattern is generated by interfering two coherent beams of light at different frequencies. Light which is incident on the photoconductive layer of the detector will generate photocarriers with a specific drift velocity proportional to the applied bias voltage. For a fixed angle between the two beams, a resonance peak occurs when the drift velocity equals the fringe velocity of the moving interference pattern. Detection of a broadband signal, therefore, is difficult since each frequency component produces a different fringe velocity and thus has a different resonance peak associated with the detector. Broadband detection of a signal is allowed by forcing each of the detected moving interference patterns, each corresponding to a specific temporal RF frequency, to have the same velocity as the electron drift velocity. This can be accomplished by using an AOD to linearly deflect each frequency component of the RF signal at the appropriate angle in order to maintain a constant overall fringe velocity at the TFD.
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Gregory Kriehn, Andrew M. Kiruluta, Kelvin H. Wagner, Daniel Dolfi, Jean-Pierre Huignard, "Detection and time delay of a broadband rf signal using a traveling fringes detector", Proc. SPIE 3795, Terahertz and Gigahertz Photonics, (12 November 1999); doi: 10.1117/12.370153; https://doi.org/10.1117/12.370153
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