Wavelength-selective pyroelectric THz detectors

Christopher Arose; Anthony C. Terracciano; Robert E. Peale; Subith S. Vasu

doi:10.1117/12.2618673

3 June 2022 Wavelength-selective pyroelectric THz detectors

Christopher Arose, Anthony C. Terracciano, Robert E. Peale, Subith S. Vasu

Proceedings Volume 12111, Passive and Active Millimeter-Wave Imaging XXV; 121110D (2022) https://doi.org/10.1117/12.2618673
Event: SPIE Defense + Commercial Sensing, 2022, Orlando, Florida, United States

Abstract

Pyroelectric lithium tantalate (LT) wafers were integrated with sub-wavelength resonant absorbers for spectral sensing at THz frequencies. Devices were designed using electrodynamic simulation. A periodic surface pattern of gold resonators was patterned on the surface of thin LT wafers by photolithography, using a Ti sticking layer. Reflectivity was characterized using vacuum-bench Fourier transform reflectance spectroscopy down to 0.3 THz using a globar source, mylar pellicle beamsplitters, and liquid helium-cooled bolometer at 4 K. Photoresponse was measured using a blackbody and a tunable mm-wave source, with the detector thermally isolated in a vacuum box with polyethylene window. The spectra reveal a pair of absorption bands separated by 0.30 to 0.45 THz. The maximum absorption varies between 30 and 70 % as a function of design parameters. The resonances are insensitive to incidence angle or polarization. Experimental results agree with design predictions. The sticking layer used for gold adhesion was found by the simulation to shift the resonance frequencies by up to 7%, to decrease the maximum absorption, and to broaden the resonances. The LT thickness of 50 micron was chosen to be thin enough to have low thermal mass but thick enough to be handled during processing. However, some of the responses can be attributed to Fabry-Perot resonances when the wavelength in LT becomes comparable to the LT thickness, so a more spectrally pure response would be achieved by avoiding those thicknesses.

Conference Presentation

Citation Download Citation

Christopher Arose, Anthony C. Terracciano, Robert E. Peale, and Subith S. Vasu "Wavelength-selective pyroelectric THz detectors", Proc. SPIE 12111, Passive and Active Millimeter-Wave Imaging XXV, 121110D (3 June 2022); https://doi.org/10.1117/12.2618673

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