Terahertz Optoelectronics Researches at IMEP-LAHC
Par Jean-Louis Coutaz, Université de Savoie Mont Blanc, IMEP-LAHC, Grenoble
Mardi 18 Juin, 14h00, Salle des séminaires (215), 2ème étage, Bâtiment A4N
Abstract :
The terahertz region (formerly the far infrared) of the electromagnetic spectrum is located between infrared (optics) and microwaves (electronics). This is the spectral domain where the electromagnetic response of matter is governed at almost equal level by both displacement and conduction currents. Consequently, the efficiency of sources and detectors is very weak, which explains why studying the far infrared was so difficult and scarce up to the end of the 80’s. Among the new techniques that were proposed at those times, THz time-domain spectroscopy (TDS) is certainly among the most amazing and widespread ones. It is based on the rectification of femtosecond laser pulses to produce picosecond electromagnetic bursts and on the measurement of these waveforms using time-equivalent optoelectronic means. Then a numerical Fourier-transform permits to address the whole THz range, i.e. from some tens of GHz to some tens of THz. This technique is widely used in fundamental physics and the strong research activity is also stimulated by numerous and fruitful foreseen applications.
During this seminar, I will present first the basics of THz-TDS for colleagues who don’t know about it. Then I will describe some of our past and present research activities, like the extraction of the parameters of samples (THz refractive index and absorption coefficient) from THz-TDS data, THz generation by optical rectification in metals, sub-wavelength THz microscopy by optical rectification, polarimetric THz-TDS based on electro-optic antennas, the optimization of electro-optic sensors and their transfer to the industry.