Quantum dot photodetectors with metallic diffraction grating: Surface plasmons and strong absorption enhancement

We report our theoretical study of the effect of metallic diffraction grating on the sensitivity of quantum dot photodetectors in terahertz frequency. We have found that the effect of diffraction grating is much stronger for s-polarization than for p-polarization. For s-polarization the sensitivity of photodetectors can be enhanced by metallic diffraction grating by a few orders of magnitude. Due to strongly inhomogeneous distribution of electromagnetic field the quantum dots should be placed at special points, i.e. hot spots, where the field intensity is maximum.