Biomedical subjects

Jean-Louis Coutaz

Publications and source records attributed to Jean-Louis Coutaz.

3 recordsLinked to original sources

PubMed2005

Study of terahertz radiation generated by optical rectification on thin gold films.

Emission of terahertz (THz) radiation as a result of optical rectification of intense femtosecond laser pulses on thin gold films has been studied by time-domain THz spectroscopy. The THz amplitude was measured as a function of film thickness and incidence angle. The experiments reveal that the emitted THz field is suppressed for a thickness below 100 nm, which gives evidence of the nonlocal character of the response. The variation of incidence angle allows us to estimate the components of susceptibility tensor chi2ijk. For thicker films and near grazing incidence, the emitted THz field attains a peak value of 4 kV/cm.

Journal Article↗

PubMed2004

Optical rectification at metal surfaces.

The emission of freely propagating terahertz (THz) radiation coming from optical rectification at metallic surfaces has been detected and characterized for the first time to the authors' knowledge. The observed THz transients are induced through nonlinear electronic processes at gold and silver surfaces on intense pulsed optical photoexcitation and exhibit a peak electric field of as much as 200 V/cm. This finding opens a qualitatively new way to investigate nonlinear phenomena at metal surfaces and also can be exploited for the development of new THz emitters.

Journal Article↗

PubMed2002

Grating-assisted coupling of terahertz waves into a dielectric waveguide studied by terahertz time-domain spectroscopy.

We report on the efficient coupling of terahertz (THz) waves into a dielectric waveguide by means of a diffraction grating engraved at the top of the waveguide. The waveguide is made of a 201-microm-thick high-resistivity silicon wafer. The transmission of the device, measured versus frequency by terahertz time-domain spectroscopy, shows usual m lines when a frequency component of the THz pulse spectrum satisfies the phase-matching condition and is coupled into the waveguide. The experimental data are well modeled with the differential electromagnetic method to compute the diffraction pattern of the grating device. The dispersion curve of the first four modes of propagation is determined from the frequency position of the m lines recorded for different angles of incidence of the THz beam. The waveguide exhibits a weak group velocity dispersion at high frequencies.

Journal Article↗