Broadband THz emission of long pulses from photomixing process with optical chirped pulses.

Terahertz (THz) generation via photomixing on photoconductive antenna using twin delayed chirped pulses provides a long THz pulse with a narrow bandwidth. To generate a long pulse with a broad bandwidth, we propose a new, to the best of our knowledge, method that combines two long optical pulses with opposite chirps. The pulses exhibit temporal distributions of their instantaneous frequencies with opposite slopes.

Terahertz diffractive imaging with saturated data inpainting.

Multiplane iterative phase retrieval is a promising approach to diffraction imaging, which accurately determines the topographic and internal characteristics of various objects. Nevertheless, the detection systems used often have a limited dynamic range, resulting in overexposure of recorded intensity distributions. In this Letter, we present a novel, to the best of our knowledge, reconstruction algorithm that inpaints saturated areas on the measured intensity datasets and reliably retrieves wave complex amplitude.

Terahertz Nondestructive Testing with Ultra-Wideband FMCW Radar.

This paper presents the development, performance, integration, and implementation of a 150 GHz FMCW radar based on a homodyne harmonic mixing scheme for noncontact, nondestructive testing. This system offers high-dynamic-range measurement capabilities up to 100 dB and measurement rates up to 7.62 kHz.

Terahertz refractive index-based morphological dilation for breast carcinoma delineation.

This paper reports investigations led on the combination of the refractive index and morphological dilation to enhance performances towards breast tumour margin delineation during conserving surgeries. The refractive index map of invasive ductal and lobular carcinomas were constructed from an inverse electromagnetic problem. Morphological dilation combined with refractive index thresholding was conducted to classify the tissue regions as malignant or benign.

Terahertz phase retrieval imaging in reflection.

Terahertz phase retrieval is a promising technique able to assess the complex diffracted wave properties through an iterative processing algorithm. In this Letter, we demonstrate the implementation of this technique in reflection geometry with a continuous wave acquisition system working at 0.287 THz.

A Versatile Illumination System for Real-Time Terahertz Imaging.

Terahertz technologies are attracting strong interest from high-end industrial fields, and particularly for non-destructive-testing purposes. Currently lacking compactness, integrability as well as adaptability for those implementations, the development and commercialisation of more efficient sources and detectors progressively ensure the transition toward applicative implementations, especially for real-time full-field imaging. In this work, a flexible illumination system, based on fast beam steering has been developed and characterized.

Guided terahertz pulse reflectometry with double photoconductive antenna.

Developments toward the implementation of a terahertz pulse imaging system within a guided reflectometry configuration are reported. Two photoconductive antennas patterned on the same LT-GaAs active layer in association with a silica pipe hollow-core waveguide allowed us to obtain a guided optics-free imager. Besides working in a pulsed regime, the setup does not require additional optics to focus and couple the terahertz pulses into the waveguide core, simplifying the global implementation in comparison with other reported guided terahertz reflectometry systems.

Terahertz Spectroscopy and Quantum Mechanical Simulations of Crystalline Copper-Containing Historical Pigments.

Terahertz spectroscopy, a noninvasive and nondestructive analytical technique used in art conservation and restoration, can provide compelling data concerning the composition and condition of culturally valuable and historical objects. Terahertz spectral databases of modern and ancient artists' pigments exist but lack explanations for the origins of the unique spectral features. Solid-state density functional theory simulations can provide insight into the molecular and intermolecular forces that dominate the observed absorption features as well as reveal deviations from simple harmonic vibrational behavior that can complicate these spectra.

Pilot study of freshly excised breast tissue response in the 300-600 GHz range.

The failure to accurately define tumor margins during breast conserving surgery (BCS) results in a 20% re-excision rate. The present paper reports the investigation to evaluate the potential of terahertz imaging for breast tissue recognition within the under-explored 300 - 600 GHz range. Such a frequency window matches new BiCMOS technology capabilities and thus opens up the opportunity for near-field terahertz imaging using these devices.

Terahertz frequency modulated continuous wave imaging advanced data processing for art painting analysis.

Reflection terahertz frequency modulated continuous waves scanner (300 GHz) has been proficiently optimized for imaging two easel paintings of different age. The information content of the obtained THz images has been fully inspected by selecting the appropriate THz image parameter. At the same time, a new data processing has been developed for improving the level of detail held by the axial parametric THz images by means of Gaussian fit of the reflected signals.

Ultra-flexible multiband terahertz metamaterial absorber for conformal geometry applications.

Standard optical lithography relying on clean room and microelectronic facilities is used to fabricate a thin-flexible metamaterial absorber, designed to operate at submillimeter wavelengths over the 0.1-1 THz frequency band. Large terahertz absorption has been demonstrated numerically and through experimental measurements with a maximum level of about 80%.