Spectrally Selective Lithium Tantalate Pyroelectric Terahertz Detector

• Published in: IEEE sensors journal 2024-09, Vol.24 (17), p.27429-27435
• Main Authors: Arose, Christopher, Peale, Robert E., Terracciano, Anthony C., Fredricksen, Chris J., Vasu, Subith S.
• Format: Article
• Language: English
• Subjects: Backward waves; Capacitance; Chemical compounds; Chemical detection; Design parameters; Detectors; Inductors; Lithium tantalates; Metals; Narcotics; Permittivity; Pyroelectric devices; remote sensing; Resonant frequency; Room temperature; Sensors; submillimeter-wave devices; Surface waves; terahertz (THz) metamaterials; Terahertz frequencies
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2024.3425721

Pyroelectric lithium tantalate (LiTaO3 or LT) wafers were integrated with subwavelength resonant absorbers to create spectrally selective room-temperature detectors at submillimeter wavelengths and terahertz (THz) frequencies. Photoresponse resonances were measured using a tunable backward wave oscillator (BWO) in the range of 0.3-1.0 THz. The resulting sensor characteristics agree well with design predictions from electrodynamic simulations, which reveal the dependence of resonant absorption on design parameters. Maximum responsivity and detectivity without electrical amplification were ~340 V/W and 6\times 10^{{6}} Jones [( \text {cm}\cdot \surd Hz) / W], respectively. The selectivity and responsivity can be understood in terms of inductor-capacitor (LC) resonances that heat the pyroelectric near the surface, followed by rapid thermal equilibration through the bulk. The response voltage that appears between surfaces is in reasonable agreement with the estimated temperature rise and the known LT pyroelectric coefficient. An array of such detectors may function as a compact THz spectrometer for standoff detection of chemical compounds including (e.g.,) opioids.