High-density low-crosstalk waveguide superlattices can potentially help shrink the pitch of an optical phased array to half-wavelength, which may lead to superior beam characteristics. While a superlattice’s longitudinal coherence is exploited to create phase mismatch and reduce crosstalk, its transverse coherence is also modified and will inevitably disturb the beam forming of the optical phased array. Our theory shows that the transverse and longitudinal coherence can be balanced in a nontrivial superlattice such that superlattice-induced disturbance of the beam can be suppressed without compromising crosstalk. Large supercells less restrained by symmetry offer more degrees of freedom for finding a desirable superlattice structure. The supercell configuration order and structural modulation strength are crucial to balancing coherence and approaching the ideal characteristics of a half-wavelength pitch optical phased array. Experimental results show a high main-beam energy ratio, low sidelobe levels, and a wide angular scanning range. Such optical phased arrays may potentially open up further opportunities for light detection and ranging (LIDAR), wireless optical communications, and biomedical scanning imaging.

中文翻译：

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基于波导的超晶格光学相控阵

高密度，低串扰波导超晶格可以潜在地帮助将光学相控阵的节距缩小到一半波长，这可能会导致出众的光束特性。虽然利用了超晶格的纵向相干性来产生相位失配并减少串扰，但其横向相干性也被修改，将不可避免地干扰光学相控阵的光束形成。我们的理论表明，在非平凡的超晶格中可以实现横向和纵向相干的平衡，从而可以在不影响串扰的情况下抑制超晶格对光束的干扰。不受对称性约束的大型超级电池为找到所需的超晶格结构提供了更大的自由度。超级单元的配置顺序和结构调制强度对于平衡相干性并接近半波长间距光学相控阵的理想特性至关重要。实验结果表明，高的主光束能量比，低的旁瓣电平和宽的角度扫描范围。此类光学相控阵可能会为光检测和测距（LIDAR），无线光通信和生物医学扫描成像带来更多机会。