Spectrally Selective Lithium Tantalate Pyroelectric Terahertz Detector

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.