LAUSR

Triplet excitons in organic materials are nonradiative and tightly bound as self-trapped ones due to the strong electron-lattice coupling. They exhibit a finite radius and long lifetime and so can be regarded as the isolated quantum dots. In this work, we theoretically demonstrate that the spin polarization of self-trapped triplet excitons can be coherently controlled by the short circularly polarized laser pulses, acting as a helicity-dependent all-optical switching effect. Such a switching can be achieved within dozens of femtoseconds and conducted in a reproducible manner. The pulse parameter dependence on the switching ratio is further investigated. Our calculation provides a theoretical foundation for exploring the ultrafast all-optical recording and information processing technique based on the organic materials.