Figure 1: THz emission experiment and raw data.
From: Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi2Se3
(a) Schematic of the ultrafast photocurrent amperemeter. A Bi2Se3 crystal is excited by a femtosecond laser pulse, resulting in a photocurrent burst and, consequently, emission of a THz electromagnetic pulse. Measurement of the transient THz electric field components Ex(t) and Eyz(t) by electro-optic sampling provides access to the sheet current J(t) flowing inside the sample. (b) Typical x- and yz-polarized THz electro-optic signals Sx and Syz measured for various settings of pump polarization and sample azimuth ϕ. The signals are offset for clarity. (c) Amplitude spectra of the THz signal and (d) THz electric field directly behind the sample as extracted from b.
