A multi-point microwave interferometer (MPMI) concept was previously proposed by the authors for spatially-resolved, non-invasive tracking of a shock, reaction, or detonation front in energetic media [P. Specht et al., AIP Conf. Proc. 1793, 160010 (2017).]. The advantage of the MPMI concept over current microwave interferometry techniques is its detection of Doppler shifted microwave signals through electro-optic (EO) modulation of a laser. Since EO modulation preserves spatial variations in the Doppler shift, collecting the EO modulated laser light into a fiber array for recording with an optical heterodyne interferometer yields spatially-resolved velocity information. This work demonstrates the underlying physical principle of the MPMI diagnostic: the monitoring of a microwave signal with nanosecond temporal resolution using an optical heterodyne interferometer. For this purpose, the MPMI concept was simplified to a single-point construction using two tunable 1550 nm lasers and a 35.2 GHz microwave source. A (110) ZnTe crystal imparted the microwave frequency onto a laser, which was combined with a reference laser for determination of the microwave frequency in an optical heterodyne interferometer. A single, characteristic frequency associated with the microwave source was identified in all experiments, providing a means to monitor a microwave signal on nanosecond time scales. Lastly, areas for improving the frequency resolution of this technique are discussed, focusing on increasing the phase-modulated signal strength.
Specht, Paul E. and Jilek, Brook A.. "Electro-optic modulation of a laser at microwave frequencies for interferometric purposes." Review of Scientific Instruments, vol. 88, no. 2, Feb. 2017. https://doi.org/10.1063/1.4975016
Specht, Paul E., & Jilek, Brook A. (2017). Electro-optic modulation of a laser at microwave frequencies for interferometric purposes. Review of Scientific Instruments, 88(2). https://doi.org/10.1063/1.4975016
Specht, Paul E., and Jilek, Brook A., "Electro-optic modulation of a laser at microwave frequencies for interferometric purposes," Review of Scientific Instruments 88, no. 2 (2017), https://doi.org/10.1063/1.4975016
@article{osti_1349334,
author = {Specht, Paul E. and Jilek, Brook A.},
title = {Electro-optic modulation of a laser at microwave frequencies for interferometric purposes},
annote = {A multi-point microwave interferometer (MPMI) concept was previously proposed by the authors for spatially-resolved, non-invasive tracking of a shock, reaction, or detonation front in energetic media [P. Specht et al., AIP Conf. Proc. 1793, 160010 (2017).]. The advantage of the MPMI concept over current microwave interferometry techniques is its detection of Doppler shifted microwave signals through electro-optic (EO) modulation of a laser. Since EO modulation preserves spatial variations in the Doppler shift, collecting the EO modulated laser light into a fiber array for recording with an optical heterodyne interferometer yields spatially-resolved velocity information. This work demonstrates the underlying physical principle of the MPMI diagnostic: the monitoring of a microwave signal with nanosecond temporal resolution using an optical heterodyne interferometer. For this purpose, the MPMI concept was simplified to a single-point construction using two tunable 1550 nm lasers and a 35.2 GHz microwave source. A (110) ZnTe crystal imparted the microwave frequency onto a laser, which was combined with a reference laser for determination of the microwave frequency in an optical heterodyne interferometer. A single, characteristic frequency associated with the microwave source was identified in all experiments, providing a means to monitor a microwave signal on nanosecond time scales. Lastly, areas for improving the frequency resolution of this technique are discussed, focusing on increasing the phase-modulated signal strength.},
doi = {10.1063/1.4975016},
url = {https://www.osti.gov/biblio/1349334},
journal = {Review of Scientific Instruments},
issn = {ISSN 0034-6748},
number = {2},
volume = {88},
place = {United States},
publisher = {American Institute of Physics},
year = {2017},
month = {02}}
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