Ultrabroadband terahertz time-domain spectroscopy using III-V photoconductive membranes on silicon.

Electromagnetic waves in the terahertz (THz) frequency range are widely used in spectroscopy, imaging and sensing. However, commercial, table-top systems covering the entire frequency range from 100 GHz to 10 THz are not available today. Fiber-coupled spectrometers, which employ photoconductive antennas as emitters and receivers, show a bandwidth limited to 6.

Intercomparison of far-infrared transmittance measurements.

We present the results of the first systematic "round-robin" comparison of far-infrared transmittance spectra measurements, which was performed by five laboratories and piloted by Physikalisch-Technische (PTB). The transmittance spectra of four different samples were measured by the participating laboratories in the 600 cm to 10 cm range (16.67 µm to 1000 µm) in a blind comparison.

Background corrected measurements of optical quantities in the far-infrared spectral range.

By definition, optical quantities transmittance and reflectance can basically be determined as the ratio of two flux measurements. One measurement is performed with, and the other without, the sample under test in the optical path. However, at longer wavelengths the temperature radiation of the sample itself as well as of the applied spectrometer and detector increasingly contribute to the detected radiation budget.

Planar hyperblack absolute radiometer.

The absolute responsivity of a planar cryogenic radiometer fabricated from micromachined silicon and having carbon nanotubes, as the absorber and thermistor were measured in the visible and far infrared (free-field terahertz) wavelength range by means of detector-based radiometry. The temperature coefficient of the thermistor near 4.8 K and noise equivalent power were evaluated along with independent characterization of the window transmittance and specular reflectance of the nanotube absorber.

A highly linear superconducting bolometer for quantitative THz Fourier transform spectroscopy.

A superconducting transition edge sensor (TES) bolometer operating in the spectral range from 0.1 THz to 3 THz was designed. It is especially intended for Fourier transform spectroscopy and features a higher dynamic range and a highly linear response at a similar response compared to commercially available silicon composite bolometers.

Traceable terahertz power measurement from 1 THz to 5 THz.

The metrology institute in Germany, the Physikalisch-Technische Bundesanstalt (PTB), calibrates the spectral responsivity of THz detectors at 2.52 THz traceable to International System of Units. The Terahertz detector calibration facility is equipped with a standard detector calibrated against a cryogenic radiometer at this frequency.

Optical methods for power measurement of terahertz radiation.

Precision power measurements of terahertz (THz) radiation are required to establish metrological applications in the THz spectral range. However, traceability to the International System of Units (SI) has been missing in the THz region in the past. The Physikalisch-Technische Bundesanstalt (PTB), as the national metrology institute of Germany, determines the spectral responsivity of detectors for THz radiation by using two complementary optical methods: source- and detector-based radiometry.