Absolute self-calibrated room-temperature terahertz powermeter.

Coupling optical and thermal properties of a terahertz (THz) thermal converter based on the Seebeck effect provides an unsupplied room-temperature measuring device dedicated to THz power metrology. Performance characteristics such as broadband response (0-30 THz), high sensitivity (<25 μW·Hz(-0.5)), and the possibility to develop an internal absolute self-calibration estimated at 9.

Three-dimensional terahertz computed tomography of human bones.

Three-dimensional terahertz computed tomography has been used to investigate dried human bones such as a lumbar vertebra, a coxal bone, and a skull, with a direct comparison with standard radiography. In spite of lower spatial resolution compared with x-ray, terahertz imaging clearly discerns a compact bone from a spongy one, with strong terahertz absorption as shown by additional terahertz time-domain transmission spectroscopy.

Terahertz tomographic imaging of XVIIIth Dynasty Egyptian sealed pottery.

A monochromatic millimeter-wave imaging system coupled with an infrared temperature sensor has been used to investigate historic objects preserved at the Museum of Aquitaine (France). In particular, two-dimensional and three-dimensional analyses have been performed in order to reveal the internal structure of nearly 3500-year-old sealed Egyptian jars.

Submicrometer digital in-line holographic microscopy at 32 nm with high-order harmonics.

Soft-x-ray digital in-line microscopic holography is achieved using a fully coherent high-order harmonic source emitting at 32 nm. Combination of commercial-grade soft-x-ray optics and a back-illuminated CCD detector allows a compact and versatile holographic setup. Different experimental geometries have been tested by imaging calibrated 50 nm tips and 1 microm wires.

Frequency chirp of long electron quantum paths in high-order harmonic generation.

We report on the first experimental measurement of the spectral broadening of the harmonic emission associated with only the long electron quantum paths as a function of the driving pulse intensity. For such measurements we have estimated the chirp coefficient associated with the long quantum paths, within the strong-field approximation. This coefficient describes how the harmonic phase depends on the intensity of the driving laser field.

Direct measurement of wave-front distortion induced during second-harmonic generation: application to breakup-integral compensation.

The wave-front distortion of femtosecond laser pulses recorded with a Shack-Hartmann analyzer makes it possible to retrieve the nonlinear index of refraction of different glasses and the nonlinear phase shift induced during second-harmonic generation in beta-barium borate (BBO) crystal versus the phase mismatch. It is shown that the nonlinear phase shift induced in a 2-mm-thick BBO crystal allows compensation for up to a 2pi breakup-integral induced in a 4-cm fused-silica glass. The stability of the compensation is reported to be from 10 to 100 GW cm(-2).