1. General
THz non-linear spectroscopy is expected to provide new information about atom, molecular, and solid-state fundamental resonances. Obviously THz non-linear measurements demand high power THz sources. So far only a few studies on THz nonlinear spectroscopy have been done. Most of these studies were performed with THz pulses generated by Free Electron Lasers (FEL). However, extremely high cost of FEL’s significantly limits its wide use for the THz non-linear spectroscopy.
We offer a generator of ultra-short THz pulses Tera-Ax providing nJ pulse energy level. The Tera-Ax requires pumping by a femtosecond Ti:S amplifier such as our Regulus or Multus products. Other commercial femtosecond laser amplifiers also can be used for Tera-Ax pumping. Tera-Ax can be used for THz non-linear spectroscopy, large area THz imaging and other THz photonics purposes demanding high-energy ultra-short THz pulses. THz generation in Tera-Ax is based on phase-matched optical rectification in MgO:LiNbO₃. The phase-matched condition is reached by tilting of femtosecond laser pulse fronts. Currently optical rectification with tilted femtosecond pulses provides the highest rate of optical-to-THz conversion efficiency.
We also offer the Tera-Ax equipped with the optional EO-AX electro-optic detector providing measurement of electric field temporal profile of THz pulses. Amplitude and phase spectra of THz pulses can be obtained from temporal data by standard Fast Fourier Transform procedure. Two modifications of the EO-AX utilizing probe beam from amplified femtosecond system and from femtosecond master oscillator are available. The second modification provides about 2 orders of magnitude better signal-to-noise ratio in comparison with the first modification.
