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Dynamically tuned non-classical light emission from atomic defects in hexagonal boron nitride
2019, Lazić, Snežana, Espinha, André, Yanguas, Sergio Pinilla, Gibaja, Carlos, Zamora, Félix, Ares, Pablo, Chhowalla, Manish, Paz, Wendel S., Palacios Burgos, Juan José, Hernández-Mínguez, Alberto, Santos, Paulo V., van der Meulen, Herko P.
Luminescent defects in hexagonal boron nitride (h-BN) have recently emerged as a promising platform for non-classical light emission. On-chip solutions, however, require techniques for controllable in-situ manipulation of quantum light. Here, we demonstrate the dynamic spectral and temporal tuning of the optical emission from h-BN via moving acousto-mechanical modulation induced by stimulated phonons. When perturbed by the propagating acoustic phonon, the optically probed radiative h-BN defects are periodically strained and their sharp emission lines are modulated by the deformation potential coupling. This results in an acoustically driven spectral tuning within a 2.5-meV bandwidth. Our findings, supported by first-principles theoretical calculations, reveal exceptionally high elasto-optic coupling in h-BN of ~50 meV/%. Temporal control of the emitted photons is achieved by combining the acoustically mediated fine-spectral tuning with spectral detection filtering. This study opens the door to the use of sound for scalable integration of h-BN emitters in nanophotonic and quantum information technologies. © 2019, The Author(s).
Sub-cycle valleytronics: control of valley polarization using few-cycle linearly polarized pulses
2021, Jiménez-Galán, Álvaro, Silva, Rui E. F., Smirnova, Olga, Ivanov, Misha
So far, it has been assumed that selective excitation of a desired valley in the Brillouin zone of a hexagonal two-dimensional material has to rely on using circularly polarized fields. We theoretically demonstrate a way to control the valley excitation in hexagonal 2D materials on a few-femtosecond timescale using a few-cycle, linearly polarized pulse with controlled carrier–envelope phase. The valley polarization is mapped onto the strength of the perpendicular harmonic signal of a weak, linearly polarized pulse, which allows to read this information all-optically without destroying the valley state and without relying on the Berry curvature, making our approach potentially applicable to inversion-symmetric materials. We show applicability of this method to hexagonal boron nitride and MoS2.