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, Japan
Hideaki Kitahara  -  Research Center for Development of Far Infrared Region, University of Fukui, Japan
Takeshi Moriyasu  -  School of Engineering, University of Fukui, Japan
Masahiko Tani  -  Research Center for Development of Far Infrared Region, University of Fukui, Japan
Received: 9 Apr 2019; Accepted: 16 May 2019; Published: 20 Jun 2019; Available online: 31 May 2019.
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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.

terahertz; instrumentation; pump and probe; spectroscopy;

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