Photoinduced diffraction grating in hybrid artificial molecule.

Photoinduced diffraction grating is theoretically investigated in a three-level ladder-type hybrid artificial molecule comprised of a semiconductor quantum dot (SQD) and a metal nanoparticle (MNP). The SQD and the MNP are coupled via the Coulomb interaction. The probe absorption vanishes under the action of a strong coupling field, indicating an effect of electromagnetically induced transparency (EIT). Based on this EIT effect, diffraction grating is achievable when a standing-wave coupling field is applied. It turns out that the efficiency of diffraction grating is greatly improved due to the existence of the MNP. Furthermore, the diffraction efficiency can be controlled by tuning the interaction strength between the SQD and the MNP. Nearly pure phase grating is obtained, showing high transmissivity and high diffraction efficiency up to 33%.