Karine Blary

Terahertz Corrugated and Bull's-Eye Antennas

The radiation and temporal properties of one-dimensional and two-dimensional (Bulls-eye) corrugated antennas are investigated numerically and experimentally at terahertz. The thickness of the antenna is miniaturized, within the fabrication limits, by using the transverse slot resonance rather than the longitudinal resonance. Square and triangular corrugations are discussed. The comparison between these two profiles shows that, in terms of return loss and gain, the antenna is robust to the corrugation shape, which alleviates the fabrication complexity. The temporal analysis of the Bulls eye antenna is also shown to demonstrate the contributions coming from the leakage of the surface wave at each groove. This insight allows us to engineer the temporal shape of the output pulse by varying independently the depth of each groove. The antennas presented here hold promise for manipulating with very low profiles pulse- and beam-shapes of THz radiation.

Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy

A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements.

THz surface plasmon modes on planar Goubau lines.

The dispersion relation and confinement of terahertz surface plasmon modes propagating along planar Goubau lines are studied using guided-wave time domain spectroscopy. We demonstrate the radial nature of the surface plasmon mode known as the Goubau mode and the transverse confinement of the electric field over a few tenths of microns (~l/10). We experimentally and computationally observed a transition of the shape of the THz pulses from unipolar to bipolar as the propagation distance increases, indicating that the Goubau line acts as a high-pass filter. The deviation of the dispersion relation curve from a linear law above 600 GHz is discussed.

High gain leaky wave antenna operating at 0.566 THz

Metallic structures consisting of a central λ0/2 slot surrounded by straight parallel wedge corrugations present high transmission enhancement for an impinging EM beam, compared to that given by a single central slot with no grooves. Here, a 0.566 THz low profile leaky-wave antenna (LWA) with triangular corrugations is numerically and experimentally analyzed. Negligible differences are observed between triangular and typical square corrugation profiles. A manufactured prototype is also numerically and experimentally studied. LWAs are of high interest in several frequency ranges, including the expanding range of the THz.

Low profile THz periodic leaky-wave antenna

In this work, a 0.566THz flat leaky-wave antenna, consisting of a central λ0/2 slot surrounded by straight parallel wedge corrugations, is numerically and experimentally analyzed. Simulations show a moderately high gain and no significant differences when compared with a typical square corrugation profile. Numerical comparison is also made for the designed and manufactured antennas. High transmission enhancement in the corrugated case is obtained, compared to that given by a single central slot with no grooves. This kind of antennas finds several applications in different frequency ranges, including the nowadays high-interest range of the THz.

Flat THz launcher antenna

1D and 2D leaky-wave corrugated antennas working at terahertz frequencies are numerically and experimentally studied. These structures allow temporal-pulse and beam shaping by engineering the leakage rate of the surface waves induced by the corrugations.