We have successfully developed and thoroughly characterized a large-aperture active liquid crystal (LC) device, specially designed to operate in the terahertz (THz) frequency range. This innovative device consists of a layer of nematic liquid crystals sandwiched between glass plates with interdigitated electrodes. While liquid crystals are widely recognized as effective phase modulators in the visible and infrared spectra, their application in the THz range is limited and experimental. Thanks to meticulous experimentation using a THz time-domain spectroscopy system (THz-TDS), we have systematically evaluated the phase modulation capabilities of our liquid crystal device over a wide frequency spectrum. This evaluation not only validated the device's performance, but also highlighted its spatial uniformity, which is crucial for applications requiring precise phase control over a large area. More specifically, our measurements demonstrated consistent phase modulation effects across the entire 25 mm diameter of the liquid crystal device, affirming its potential for practical applications in THz wave manipulation. In addition, taking advantage of our facility's broadband THz imaging capability, we performed comprehensive spatial mapping to assess phase modulation uniformity across the large aperture. This capability is essential for deploying LC devices as cost-effective phase plates in THz-wave systems, where uniform phase modulation is key to achieving desired results in imaging and communication technologies. In summary, this study marks a significant advance in the development of LC devices suitable for THz frequencies, providing insight into their operational characteristics and paving the way for their integration into next-generation THz technologies. Our results highlight the potential of LC-based solutions to improve the functionality and affordability of THz wave processing systems, promising wider applications in fields such as spectroscopy, imaging and telecommunications.
| Date | 12 Nov 2024 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | François Blanchard (Supervisor) |
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Le Bourlout, A. (Author),
Blanchard (Supervisor),
12 Nov 2024Student thesis: Master's thesis › Master in Engineering: Engineering