Characterization of a Large-Area Pyroelectric Detector from 300 GHz to 30 THz

Abstract

The national metrology institute of Germany, the Physikalisch-Technische Bundesanstalt (PTB), together with the company Sensor and Lasertechnik (SLT), develops pyroelectric detectors for radiation in the terahertz (THz) spectral range. The intention of this development is to deliver a highly sensitive, accurately calibrated detector for power measurement in the power range of time-domain spectroscopy (TDS) systems. This work reports about a large-area thin-film pyroelectric (TFP) detector applicable within a wide spectral range from 300 GHz to 30 THz and its radiometric characterization by PTB's THz radiation sources. Applying coherent synchrotron radiation from the Metrology Light Source (MLS), laser radiation from a molecular gas laser and blackbody radiation from a water-heated blackbody to this detector reveal its potential to be capable of spanning an even wider THz frequency range than covered by TDS systems. To demonstrate this, its spectral responsivity was measured at different frequencies between 300 GHz and 30 THz by means of those three THz radiation sources.

Comparison between dielectric and pyroelectric properties of PZFNT and BST type ceramics

“…The hysteresis loops of these materials are quite different. The total polarization loop of BST is very slim, typical for a relaxor ceramics [12,13] compared to PZFNT loop, but shows a maximum polarization similar to that of PZFNT. The value of remnant polarization is the main difference between the hysteresis loops of these materials.…”

“…Two specific compositions were selected, namely Ba 0.75 Sr 0.25 TiO 3 (BST) and PbZr 0.68 Fe 0.14 Nb 0.14 Ti 0.04 O 3 (PZFNT), knowing that dopants in BST and PZT lead to lower transition temperatures, thus to larger values for the pyroelectric coefficient. One has also to mention that pyroelectric properties are usually investigated on samples of small area [10], and only few studies were performed on large area pyroelectric elements manufactured from ferroelectric polymers [11,12]. In the present study these properties are investigated on perovskite ceramic samples of large area, comparable to those used in commercial energy meters.…”

Selective Pyroelectric Detection of Millimetre Waves Using Ultra-Thin Metasurface Absorbers

“…Pyroelectric detectors are proven to be one of the most effective, compact and relatively inexpensive types of uncooled thermal sensors widely used for infrared (IR) detection 1 . Nowadays, following a fast progress in terahertz (THz) and millimetre-wave (MMW) technologies 2 3 4 5 , a lot of efforts are being made to improve the sensitivity of pyroelectric detection at longer wavelengths λ far beyond the IR range 5 6 7 8 9 10 . In particular, the short MMW and sub-MMW bands (λ ≈ 0.5–3 mm) remain highly attractive for various applications, including security imaging and surveillance, nondestructive evaluation and quality control of materials etc., due to an opportunity to combine the options of relativity high penetrability of such waves through atmosphere and different non-metallic objects versus high-frequency THz, IR and optical radiation, as well as attainability of spatial resolution of the order of several millimetres acceptable for imagining of concealed targets 2 3 4 11 .…”

“…This problem appears due to rapidly diminishing absorption of long-wave radiation in a thin pyroelectric film when the wavelength increases. Currently, noticeable technological efforts are being undertaken to create a sensitive broadband pyro-detector applicable to spectroscopy tasks that is achieved via integration of absorptive metallic, oxide or carbon nanotubes coatings with pyroelectric films 9 10 . On the other hand, in spectrally selective detection the detector’s sensitivity can be maximized if the radiation is absorbed by a thin metamaterial structure whose heating is further sensed with a pyroelectric.…”

Analysis and design of efficient passive components for the millimeter-wave and THz bands

“…Therefore, these detectors are used presently for CW detection in imaging applications at room temperature [236]- [237]. A very recent work [238] concludes that pyroelectric detectors offers lower SNR than microbolometers at high frequencies in the THz band.…”