Topology plays a fundamental role in contemporary physics and enables new information processing schemes and wave device physics with built-in robustness. However, the creation of photonic topological phases usually requires complex geometries that limit the prospect for miniaturization and integration, and, dispossess designers of additional degrees of freedom needed to control topological modes on-chip. By controlling the degree of asymmetry (DoA) in a photonic crystal with broken inversion symmetry, we report single-mode lasing of valley-Hall ring cavities at telecommunication wavelength. Our results open the door to novel optoelectronic devices and systems based on compact topological integrated circuits.
KEYWORDS: Beam shaping, Particles, Phase shifts, Near field, Information security, Polarization, Diffraction, Near field optics, Reflection, Optimization (mathematics)
Insensitivity of random systems to the polarization of incident light even for anisotropic and asymmetric particles, larger information capacity and higher level of information transport security as a result of larger degrees of freedom and the absence of spurious diffraction orders observed in periodic structures with large periodicity are among unique features making disordered structures a promising candidate to address challenges in the optical wave manipulations. Most of the metasurfaces are arranged in a periodic grid and the required phase profile for a desired performance is achieved by engineering elements via extracted information from periodic/unit cell simulation definitely not addressing the near field coupling between randomly positioned elements and so not helpful for the design of disordered metasurfaces. In this numerical study, we show how random arrangement of particles affect their phase shift compared to the periodic ones. We propose a new phase-map to design random metasurfaces benefiting from the statistical nature of random media and addressing the near field coupling between resonant elements. This phase-map provides us with the information on the geometry of particles located at random positions for a specific phase shift. Design of random metasurfaces by the proposed random phase-map reveals efficiency improvement compared to those designed based on periodic phase-map. We hope this new phase-map can pave the way towards random optical system outperforming the periodic counterpart in secure optical information processing.
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