Employing phase modulation and second harmonic nulling to eliminate the interference fringes from the spectrum of a portable coherent frequency-domain THz spectrometer

Joseph R. Demers; Bryon L. Kasper

doi:10.1117/12.2016054

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31 May 2013 Employing phase modulation and second harmonic nulling to eliminate the interference fringes from the spectrum of a portable coherent frequency-domain THz spectrometer

Joseph R. Demers, Bryon L. Kasper

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Proceedings Volume 8716, Terahertz Physics, Devices, and Systems VII: Advanced Applications in Industry and Defense; 87160M (2013) https://doi.org/10.1117/12.2016054
Event: SPIE Defense, Security, and Sensing, 2013, Baltimore, Maryland, United States

Abstract

Interpreting the spectrum from a continuous wave frequency domain terahertz spectrometer that employs coherent detection can be challenging due to the presence of an interference pattern. We report on the continued progress of a portable, battery-operated frequency domain terahertz spectrometer with an integrated, fiber-coupled, lithium-niobate optical phase-modulator and how we achieve interference fringe elimination using phase modulation and second harmonic nulling. The implications for both transmission and reflection measurements are discussed and data on the explosive compound RDX will be presented.

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Joseph R. Demers and Bryon L. Kasper "Employing phase modulation and second harmonic nulling to eliminate the interference fringes from the spectrum of a portable coherent frequency-domain THz spectrometer", Proc. SPIE 8716, Terahertz Physics, Devices, and Systems VII: Advanced Applications in Industry and Defense, 87160M (31 May 2013); https://doi.org/10.1117/12.2016054

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