Optical Pump-THz probe
Ultrafast 25 fs pulses from a 1 kHz Ti:sapphire laser with a centre wavelength of 790 nm (1.6 eV) are used to simultaneously pump the THz time-domain spectrometer and the samples. The THz-TDS is equipped with ZnTe and GaSe crystal for the generation of few-cycle THz pulses with a 0.1-30 THz bandwidth (3-1000 cm-1, 0.4-120 meV) that are delivered to the sample with a system of 90° off-axis parabolic mirrors. Pump beams at 1.6 eV (790nm) and its 2nd harmonics at 3.1 eV (400nm) are delivered by the same amplified laser system used for the THz-TDS set up. The THz detection scheme is in the framework of the free-space electro-optical sampling using the relevant birefringent crystal.
Forthcoming activities
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Two stage Optical Parametric Amplifier (OPA) for the generation of MIR pulses in the 3-5 μm wavelength range: the first stage delivers broadband pulses tunable between 0.9 and 1.5 microns, which subsequently seed the second OPA stage, pumped by a fraction of the laser source at 800-nm wavelength. We plan to use a periodically poled lithium niobate (PPLN) crystal that when pumped at 800 nm, display a broad phase matching bandwidth around 1 μm, allowing the direct generation of broadband idler pulses spanning the 3-5 μm wavelength range with duration down to two optical cycles. (Master Thesis available)
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Single shot Thz detection: we are developing a spectral interferometric set up for the one-shot detection of THz electric field by overcoming the time-consuming electro-optical sampling scheme. (Master Thesis available)