title: Highly precise and accurate terahertz polarization measurements based on electro-optic sampling with polarization modulation of probe pulses.
abstract: We have developed an electro-optic (EO) sampling method with polarization modulation of probe pulses; this method allows us to measure the direction of a terahertz (THz) electric-field vector with a precision of 0.1 mrad in a data acquisition time of 660 ms using a 14.0-kHz repetition rate pulsed light source. Through combination with a THz time-domain spectroscopy technique, a time-dependent two-dimensional THz electric field was obtained. We used a photoelastic modulator for probe-polarization modulation and a (111)-oriented zincblende crystal as the EO crystal. Using the tilted pulse front excitation method with stable regeneratively amplified pulses, we prepared stable and intense THz pulses and performed pulse-by-pulse analog-to-digital conversion of the signals. These techniques significantly reduced statistical errors and enabled sub-mrad THz polarization measurements. We examined the performance of this method by measuring a wire-grid polarizer as a sample. The present method will open a new frontier of high-precision THz polarization sensitive measurements.
authors.forename: Natsuki
authors.initials: N
authors.lastname: Nemoto
authors.forename: Takuya
authors.initials: T
authors.lastname: Higuchi
authors.forename: Natsuki
authors.initials: N
authors.lastname: Kanda
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Konishi
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuwata-Gonokami