Ma Zhipeng, Fu Yao, Wan Yuanjian, Cao Han, Zhang Yu, Wang Jian
Opt Express. 2024 Sep 9;32(19):33159-33173. doi: 10.1364/OE.534752.
As a novel method for solid-state light detection and ranging (LiDAR), optical phased arrays (OPAs) cater to the growing market requirement for mass-produced chip-scale beam steering devices. Waveguide grating antennas (WGAs) with low loss, high efficiency and large emitting aperture are strongly desirable to achieve low beam divergence and high resolution for OPAs. In this paper, we report two kinds of silicon ridge-waveguide-based WGAs with ultra-sharp instantaneous field-of-view (IFOV) for LiDAR applications. The ridge-concave WGA (RCC-WGA) and ridge-convex WGA (RCV-WGA) are designed on account of both sides of ridge area have relatively weak mode field distribution. Lateral quasi-bound state in the continuum (L-BIC) is utilized to further suppress side scattering and improve the emission efficiency. The RCC-WGAs and RCV-WGAs are fabricated on silicon-on-insulator (SOI) platform with 220 nm device layer and foundry compatible etching depths. The measured losses are as low as 2.64 and 2.40 dB/mm at 1550 nm wavelength. The antenna length can up to 6 mm, with theoretical beam divergences of 0.0195° and 0.0175° at the wavelength of 1550 nm, while the experimental results are 0.0251° and 0.0237°, respectively. The proposed low-beam-divergence WGAs are promising in high resolution solid-state LiDAR applications.
作为一种用于固态光探测与测距（LiDAR）的新型方法，光学相控阵（OPA）迎合了市场对大规模生产的芯片级光束转向装置不断增长的需求。为了实现OPA的低光束发散和高分辨率，具有低损耗、高效率和大发射孔径的波导光栅天线（WGA）是非常理想的。在本文中，我们报道了两种用于LiDAR应用的基于硅脊形波导的具有超锐瞬时视场（IFOV）的WGA。脊形凹面WGA（RCC-WGA）和脊形凸面WGA（RCV-WGA）是基于脊形区域两侧的模式场分布相对较弱而设计的。利用连续统中的横向准束缚态（L-BIC）进一步抑制侧向散射并提高发射效率。RCC-WGA和RCV-WGA在具有220nm器件层和与代工兼容蚀刻深度的绝缘体上硅（SOI）平台上制造。在1550nm波长下测得的损耗分别低至2.64和2.40dB/mm。天线长度可达6mm，在1550nm波长下的理论光束发散角分别为0.0195°和0.0175°，而实验结果分别为0.0251°和0.0237°。所提出的低光束发散WGA在高分辨率固态LiDAR应用中具有广阔前景。
