Ultrafast high harmonic generation in transition metal dichalcogenide quantum dots

We study theoretically the generation of high harmonics by transition metal dichalcogenides disk-shaped quantum dots placed in an ultrashort optical pulse. The quantum dots are described within a massive Dirac type effective model with infinite mass boundary conditions. For a linearly polarized pulse, the cutoff frequency and the intensities of high-order harmonics increase with the quantum dot radius. For the frequency of the pulse below the system band gap, the radiation spectra show strong dependence on the quantum dot size, while for the large pulse frequency, i.e., above the band gap, both the intensities of high harmonics and cutoff frequency weakly depend on the quantum dot radius. For an elliptically polarized pulse, the intensities of harmonics monotonically decrease with the pulse ellipticity and become strongly suppressed for a circularly pulse. The cutoff frequency also monotonic decreases with the pulse ellipticity and shows weak dependence on the quantum dot material.