Coherent control of two-photon absorption of Pr³⁺ ion by shaped ultrashort laser pulses

Enhancing the photoluminescence and depressing the background emission are important problems in rare earth ion-doped materials. In this letter, the two-photon absorption (TPA) probability in a Pr³⁺ ion system is enhanced by a factor of 12.3 by a π-phase step scanning of ultrashort laser pulses. This level is significantly higher than that achieved by a transform-limit pulse. However, the laser intensity of shaped pulse is reduced to 37% of the initial transform-limited pulse. In this method, the TPA probability can also be reduced to 58%. Furthermore, the effect of the shift of the intermediate energy level and the bandwidth of final states on TPA probability is discussed.