Experimental MethodsThe type of apparatus used for THz spectroscopy is similar to that used in other ultrafast experiments. Schematics of our two experimental set-ups, as well as descriptions of the different methods of THz generation used in our laboratory are listed below. TRTS SetupThe spectrometer used for time-resolved terahertz spectroscopy (TRTS) is based on an amplified Spectra Physics Ti:Sapphire laser system. 100 femtosecond pulses of roughly 1 mJ/pulse are produced in a 1 kHz train of 800 nm pulses. The resultant beam in split into three portions which are used to photoexcite the sample and generate and detect the THz radiation. Click here for more details. THz-TDS SetupThe spectrometer used for THz-TDS studies is an unamplified Spectra Physics Ti:Sapphire laser. It produces an 80 MHz pulse train of 800-nm pulses, with roughly 10 nJ of energy per pulse. Click here for more details. Photoconductive AntennasThis page illustrates how biased gallium arsenide is used as a source for THz radiation in our THz-TDS experiments. Click here for more details. Optical RectificationThis section discusses how THz radiation is generated and detected in the TRTS experiments. Optical rectification of a visible (800 nm) pulse in a zinc telluride crystal generates the THz pulses, while free-space electro-optic sampling in another ZnTe crystal is used to detect it. Click here for more details.
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