Silicon nitride (SiN) optical phased arrays (OPAs) have emerged as a potential alternative to their silicon counterparts, due to their potential use in enhanced solid-state light detection and ranging. Grating antennas based on a SiN waveguide suffer from a limited beam steering efficiency, owing to the relatively lower effective refractive index of the waveguide. To mitigate this limitation, we propose and demonstrate a backward-emitting SiN OPA incorporating a reinforced grating vector, which provides efficient wavelength-tuned beam steering along the longitudinal direction. Two backward-emitting OPAs were primarily characterized by their steering efficiency and the spectral emission for the main lobe, and they were compared with a forward-emitting device using a weakened grating vector. The results indicated that strengthening the grating vector for the antenna improved the beam steering efficiency but adversely affected the dependence of its directionality on the wavelength. The directionality was particularly inspected, with respect to major design parameters for the grating antennas, including the pitch and etch depth of a SiN grating, as well as the thickness of a buried oxide and SiN core layer. The proposed backward-emitting OPA scheme is expected to significantly promote its feasibility as an advanced beam scanning device.

中文翻译：

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后向发射氮化硅光学相控阵可实现高效的波长调谐光束控制

氮化硅 (SiN) 光学相控阵列 (OPA) 已成为其硅对应物的潜在替代品，因为它们可能用于增强型固态光检测和测距。由于波导的有效折射率相对较低，基于 SiN 波导的光栅天线的波束控制效率有限。为了减轻这种限制，我们提出并展示了一种包含增强型光栅矢量的后向发射 SiN OPA，可沿纵向提供有效的波长调谐光束控制。两个后向发射 OPA 的主要特征在于它们的转向效率和主瓣的光谱发射，并将它们与使用弱光栅矢量的前向发射设备进行比较。结果表明，加强天线的光栅矢量提高了波束控制效率，但不利地影响了其方向性对波长的依赖性。针对光栅天线的主要设计参数，特别检查了方向性，包括 SiN 光栅的间距和蚀刻深度，以及掩埋氧化物和 SiN 核心层的厚度。所提出的向后发射 OPA 方案有望显着提高其作为先进光束扫描设备的可行性。以及掩埋氧化物和 SiN 核心层的厚度。所提出的向后发射 OPA 方案有望显着提高其作为先进光束扫描设备的可行性。以及掩埋氧化物和 SiN 核心层的厚度。所提出的向后发射 OPA 方案有望显着提高其作为先进光束扫描设备的可行性。