Picosecond rotation of a ring-shaped optical lattice by using a chirped vortex-pulse pair

A novel method of ultrafast rotation of a ring-shaped optical lattice in the picosecond time region was proposed and demonstrated. Our ring-lattice generator was assembled by a pair of linearly chirped pulses with a time delay, a high-order birefringent retarder, and an axially symmetric polarization element. Using a mode-locked Ti:sapphire laser oscillator as a light source, stable two-, four-, and six-petaled ring-lattice rotations were demonstrated with the rotation periods of 1.6, 3.2, and 4.8 ps, respectively. Our method has the potential to open up a new technique to resonantly excite propagating quasi-particles together with their coherent enhancement.