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Wave localization by flatband mechanisms underlies prominent moiré physics and relevant applications. While typically studied in periodic superlattices, the wave-confining capability of finite-size superlattices is important both fundamentally and practically. Here, we investigate wave localization in few-cell moiré superlattices through fine tuning of band offset, which is accomplished by jointly adjusting structural parameters of constitutive lattice. Remarkably, the quality factor Q, which reflects the capability of few-cell superlattices to localize wave, can reach quite high levels with appropriate band offset. Thus, superior wave localization is feasible in few-cell superlattices, indicated by the very high Q up to 10 4 − 10 5 for single-cell superlattices and extremely high Q up to > 10 7 for double-cell superlattices. Moreover, the Q patterns are distinct for different flatband resonances and different number of cells, while narrow high-Q (∼ 10 8 ) branches appear for the triple-cell superlattices. The narrow high-Q branches are hard to be reached in practice, since it requires stringent control on structural parameters. In this respect, the double-cell superlattices are promising for exploiting unconventional effects induced by wave localization, since it can achieve extremely high-Q (> 10 7 ) resonances within a sufficiently large tuning range. These results demonstrate the profound role of band-offset tuning in achieving strong wave localization in few-cell superlattices, which is useful for on-chip applications such as lasing, optical filters, and optical harmonic generation. [ABSTRACT FROM AUTHOR]

Resolution is crucially important for optical imaging, which defines the smallest spatial feature of object that can be delivered by light wave. However, due to the wave nature of light, optical imaging is of limited resolution, widely known as Rayleigh limit or Abbe limit. Nevertheless, this limit can be overcome by considering the loopholes in the derivation of the Rayleigh limit, such as light–matter interaction, structured illumination, and near-field interference. In contrast to the conventional single-photon interference, multi-photon amplitudes responsible for optical high-order interference could be designed to possess a reduced effective wavelength, enabling the breakthrough of the Rayleigh limit. In this review, we will present recently developed super-resolution imaging schemes based on optical high-order interference, and discuss future perspectives. [ABSTRACT FROM AUTHOR]

We propose a two-photon imaging scheme with a thin dynamic scattering layer as the crucial imaging element. The constructive two-photon interference for direct imaging is built when the object is properly illuminated by an entangled two-photon source. We show that the proposed imaging scheme can be used for imaging an amplitude object with incoherent two-photon illumination, and the resolution reaches Heisenberg limit. Besides, the imaging for a phase object can also be achieved in the proposed imaging scheme with coherent two-photon illumination. [ABSTRACT FROM AUTHOR]