Abstract
The introduction of a scattering center to microdisk lasers has been considered as an effective way to tailor their far-field emissions. However, this approach is practically limited by its nearby modes with higher quality () factors and worse directionalities. In this research, by applying the simple concept of parity-time () symmetry, we demonstrate that the resonances with well-designed directionalities can be selectively excited in optical microcavities. Taking the annular microcavities as examples, the unidirectional laser emissions and single-mode operations have been realized simultaneously by breaking the symmetry. More interestingly, we find that the -symmetric modulations on the imaginary parts of the refractive index in a circular microdisk can affect the internal ray dynamics and thus generate highly directional laser emission. This research can boost both the fundamental studies and the practical applications of -symmetric systems.
- Received 1 August 2018
DOI:https://doi.org/10.1103/PhysRevA.99.033849
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