Speaker: Jerome V Moloney Affiliation: Wyant College of Optical Sciences, University of Arizona Time: 4 pm Monday, 9 March, 2020 Location: 303-610 (Physics seminar room) |
Semiconductor disk lasers are ideal testbeds for studying strong departures of carriers (electrons and holes) from quasi-Fermi distributions. Carriers, optically-pumped into high momentum states, scatter into lower momentum ones and are extracted as photons near the lasing wavelength. High peak intensity femtosecond duration pulses burn deep kinetic holes in the carrier distributions – the latter are replenished through kinetic hole filling and subsequently cool (via phonons) to the lattice temperature. I will briefly discuss our recent experiments utilizing these sources for offset-free GHz mid-IR frequency comb generation. In the extreme NLO limit, where the field coupling dominates the Coulomb potential, ultrashort pulses highly detuned from the semiconductor bandgap can expose dominant intraband interactions that can accelerate carriers across the full Brillouin zone (Bloch oscillations) and enhance harmonic generation relative to purely interband processes. Recent experiments with strong THz driving fields dramatically support this observation. Finally, in the intermediate limit of highly detuned USP interactions in gases, the effective Coulomb interaction being an order of magnitude stronger than in a semiconductor, can enhance many-body interactions between electrons transiently driven from individual nuclei. The latter disrupts the phase coherence of the induced polarization leading to a residual population of electrons in continuum states at intensities well below the tunnel ionization limit. In my talk, I will attempt to pull these apparently diverse phenomena together and discuss a new class of fully optical carrier wave resolved mathematical propagation models exhibiting novel subcycle singularities. Everyone welcome! |