Concurrent measurement of sample and reference waveforms in an optical-pump terahertz-probe system using a controlled optical diaphragm shutter

Jessica Afalla (Research Center for Development of Far Infrared Region, University of Fukui)
Hideaki Kitahara (Research Center for Development of Far Infrared Region, University of Fukui)
Takeshi Moriyasu (School of Engineering, University of Fukui)
Masahiko Tani (Research Center for Development of Far Infrared Region, University of Fukui)

Journal of Physics and Its Applications
Vol 1, No 2 (2019): May 2019

We present concurrent measurement of sample and reference terahertz waveforms for an optical-pump terahertz-probe spectrometer, using a controlled optical diaphragm shutter for the optical pump line. When waveforms are taken consecutively, laser power fluctuations and other experimental conditions can introduce spectral artefacts, thus a concurrent measurement is preferred. Instead of techniques based on double modulation, the use of the diaphragm shutter eliminates the need for a second lock-in amplifier and/or constricted alignment due to the use of a single chopper blade for modulating two signals, simultaneously. Drude fitting of the complex conductivity obtained for GaAs confirms that measurements obtained using our set-up agree with reported scattering times.