Wednesday, May 13, 2015

The Most Powerful Terahertz Pulse Ever Generated

Terahertz time-domain spectroscopy is a spectroscopic technique in which the properties of a material are probed with short pulses of THz radiation. The generation and detection scheme is sensitive to the sample material's effect on both the amplitude and the phase of the terahertz radiation. Pulsed terahertz radiation is generated by photoconductive switches (GaAs or InGaAs/InP) irradiated by femtosecond lasers. At the end, a fact Fourier transform of terahertz amplitude produces the terahertz spectrum in the frequency range 0.1 – 5 THz.

We are glad to announce that our partners from AVESTA succeeded to reach an enormous power of laser impulse which now equals 1.25 µm.
Hauri group reports on high-field terahertz transients with 0.9-mJ pulse energy produced in a 400  mm2 partitioned organic crystal by optical rectification of a 30-mJ laser pulse centered at 1.25 μm wavelength. The phase-locked single-cycle terahertz pulses cover the hard-to-access low-frequency range between 0.1 and 5 THz and carry peak fields of more than 42 MV/cm and 14 Tesla with the potential to reach over 80 MV/cm by choosing appropriate focusing optics. The scheme based on a Cr:Mg2SiO4 laser offers a high conversion efficiency of 3% using uncooled organic crystal. The collimated pump laser configuration provides excellent terahertz focusing conditions.

This high-energy THz pulsed generator of AVESTA partners helped Terasense precisely measure the ultrafast response time of our proprietary passive THz detector. Such short response time opens up the possibility to observe and resolve ultrafast transient processes in many THz applications.

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