Extreme case of Faraday effect: magnetic splitting of ultrashort laser pulses in plasmas

The Faraday effect due to magnetic-field-induced change in the optical properties takes place in a vast variety of systems from a single atomic layer of graphenes to huge galaxies. To date, it plays a pivot role in many applications such as the manipulation of light, and the probing of magnetic fields and material's properties. Basically this effect causes a polarization rotation
of light during its propagation along the magnetic field in a medium. Here, we report an extreme case of the Faraday effect that a linearly polarized ultrashort laser pulse splits in time into two circularly polarized pulses of opposite handedness during its propagation in a highly magnetized plasma. This offers a new degree of freedom to manipulate ultrashort and ultrahigh power laser pulses. Together with technologies of ultra-strong magnetic fields, it may pave the way for novel optical devices, such as magnetized plasma polarizers. Besides, it may offer a powerful means to measure strong magnetic fields in laser-produced plasmas.