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Two-quantum coherences in two-dimensional Fourier-transform (2DFT) spectra are attributed to many-body interactions. 2DFT spectroscopy allows two-quantum coherences in semiconductors to be isolated. As a result, many-body coherences can be separated from biexciton coherences.
Unexpected two-quantum resonances are observed in potassium vapor using two-dimensional Fourier-transform spectroscopy. These transitions are an unambiguous indication of many-body interactions, which arise from the long-range interatomic coupling that is responsible for resonance self-broadening.
Two-dimensional Fourier-transform spectroscopy shows a strong variation in the biexciton binding energy across the inhomogeneous absorption width. This effect is observed for both co- and cross-linearly polarized excitation, where the latter suppresses many-body interactions.
Quantum interference between single and two photon inter-band absorption processes can lead to injection of electrical currents in direct and indirect band gap semiconductors. When the optical excitation occurs through 100 fs optical pulses the transient electrical currents emit THz radiation that can be used as a probe of the ultrafast current dynamics.
Raman coherence between heavy-hole and light-hole excitons in quantum wells is isolated in an alternative spectrum and contributions from single exciton and correlated two-exciton states are studied experimentally and theoretically by excitation with different polarizations.
Homogeneous and inhomogeneous broadening of heavy- and light-hole excitons in semiconductor quantum wells are measured along with the excitation dependence of both broadenings. Isolation of disorder-induced broadening is possible with spectra in different coherent pathways.
Electrical currents are generated in clean silicon at T = 300 K using quantum interference of femtosecond fundamental and second-harmonic pulses. This efficient photoinjection of ballistic currents across the indirect bandgap is detected by the emitted terahertz radiation.
An integrated AlGaAs all-optical 188-ps delay line is characterized over the C- and L- bands. Self-switching by input intensity is achieved using a nonlinear directional coupler and a racetrack delay line.
Bragg stacks were simply fabricated from evaporated gold and spin-coated polymer layers. High reflectivity occurs for only a few bilayers; compared to single gold films nonlinear absorption is enhanced by ~7x near a Bragg resonance.
Time-resolved and power-dependent pump-probe spectroscopy determines that two-photon absorption induces a strong blue-shift of coupling resonances in a photonic crystal waveguide. Carrier relaxation times are shortened by the surface recombination, showing potential for all-optical switching.
Time-resolved and power-dependent pump-probe spectroscopy determines that two-photon absorption induces a strong blue-shift of coupling resonances in a photonic crystal waveguide. Carrier relaxation times are shortened by the surface recombination, showing potential for all-optical switching
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