Femtosecond chirped pulse control of photoluminescence and generating electron–hole pairs in broadband semiconductors

We have studied an intense chirped pulse excitation of broadband semiconductors with a direct interband transition. We concentrate on photoluminescence and generating electron–hole pairs. The important role of the pulse frequency modulation for obtaining high excited carriers’ densities has been demonstrated. We show that a mechanism of generating electron–hole pairs strongly depends on the chirp rate in the frequency domain Φ″(ν). As Φ″(ν) increases, a behavior related to the Rabi oscillations of the carriers’ densities gives way to adiabatic rapid passage and thereafter to an incoherent excitation of carriers. Correspondingly, the carriers’ densities strongly increase when the behavior related to the Rabi oscillations gives way to adiabatic rapid passage. In the incoherent regime the excited carrier densities vary slower, and the carrier–carrier scattering has severe effects on their behavior in this region.