Terahertz polarimetric emission and detection using a cubic crystal

Summary form only given. Antenna based on semi-conductors or non-linear crystals can be exploited to generate or to characterize electric (E) field in the terahertz (THz) frequency band. In the time domain, these conventional techniques involve an ultra short laser beam with duration of a few tens femtoseconds, to pump or probe the THz devices. While the field magnitude is usually tunable via the optical power for the emission, the field orientation is fixed and determined by the azimuthal angle of the antenna. Any modification of the THz polarization requires either a THz waveplate and/or a specific polarizing system. We here propose a novel configuration using optical rectification within a cubic crystal (ZnTe) along its particular orientation <;111> relatively to the optical beam. This configuration offers homogeneous transverse linear and non-linear properties leading to THz generation whatever the optical polarization state. Furthermore, the THz field transverse angle is linearly linked to the optical one. Thus, the THz polarization can be adjusted using a single optical waveplate. Concerning the detection, the same crystal orientation is probed by a single laser beam and allows to perform the transient analysis of the transverse field vector
¹
. This configuration has already been demonstrated for low frequencies and is now extended to THz regime. This leads to a device acting as a THz polarimeter without any need to rotate a THz polarizer. The theoretical and experimental validations of this concepts will be presented during the conference: a THz emitter with an easy control of the polarization state has been achieved and the transient evolution of the transverse field vector has been measured in the sub-picosecond range with a single probe. Latest advances concern also the implementation of the detection scheme for the analysis of THz plasma sources.