RESUMO
Photonic quasicrystals are poised to transform the field of nonlinear light-matter interactions due to their ability to support an unlimited number of combinations of wavevectors in their reciprocal lattices. Such greatly enhanced flexibility enabled by k-space engineering makes photonic quasicrystals a promising platform for novel approaches to multi-wavelength conversion, supercontinuum generation, and development of classical and quantum optical sources. Here, we develop a new design method for nonlinear photonic quasicrystals, consisting of a combination of one nonlinear material and one linear material that can simultaneously fulfill phase-matching conditions for a desired number of nonlinear optical interactions as long as the frequencies of the interacting waves are outside of the bandgaps of the quasicrystal structure. Our approach provides enhanced design flexibility, enabling new pathways to designing compact, integrated nonlinear photonic devices and systems on a chip.
RESUMO
We demonstrate a new method for a systematic, dynamic, high-speed, spatio-temporal control of femtosecond light filamentation in BK7 as a particular example of nonlinear medium. This method is based on using coherent conjugate asymmetric Bessel-Gaussian beams to control the far-field intensity distribution and in turn control the filamentation location. Such spatio-temporal control allows every femtosecond pulse to have a unique intensity distribution that results in the generation of structured filamentation patterns on demand. The switching speed of this technique is dependent on the rise time of the acousto-optic deflector, which can operate in the MHz range while having the ability to handle high peak power pulses that are needed for nonlinear interactions. The proposed and demonstrated spatio-temporal control of structured filaments can enable generation of large filament arrays, opto-mechanical manipulations of water droplets for fog clearing, as well as engineered radiofrequency plasma antennas.
