Zeng Xintao, Wang Hongji, Hong Ziming, Ma Yuxin, Zhu Canfeng, Wu Pinghui, Zhang Xianzeng, Shi Yuechun, Chen Xiangfei
Opt Express. 2022 Dec 19;30(26):46121-46133. doi: 10.1364/OE.476325.
Due to the ability of changing light propagation path direction, curved waveguide Bragg grating (CWG) plays an important role in photonic integrated circuits. In this paper, we proposed a cascaded sampled Bragg grating on tilted waveguide (CSBG-TW) structure to equivalently realize CWG. As an example, by designing two-dimensional (2D) sampled gratings, the direction of +1 sub-grating vector in CSBG-TW can be changed. Then if a curved waveguide is divided into several sections of tilted waveguide, we can keep the grating direction being always parallel to the longitudinal direction of each section of tilted waveguide, while the basic grating is uniform. Hence, the required CWG can be equivalently realized, and the light responses such as reflection Bragg wavelength shift and backward mode convert caused by the tilted grating in curved waveguide can be compensated for. The results show that the sampling structures of CSBG-TW is micro-scale and the difference between reflection intensity between the CSBG-TW with four section tilted waveguide and CWG as design target is less than 0.1 dB. Compared with CWG, the CSBG-TW allows convenient holographic exposure and the wavelength can be accurately controlled. Therefore, the CSBG-TW can be used in various photonic integrated devices that require changing propagation paths.
由于能够改变光传播路径方向，弯曲波导布拉格光栅（CWG）在光子集成电路中起着重要作用。本文提出了一种倾斜波导上的级联采样布拉格光栅（CSBG-TW）结构来等效实现CWG。例如，通过设计二维（2D）采样光栅，可以改变CSBG-TW中+1子光栅矢量的方向。然后，如果将弯曲波导分成几段倾斜波导，我们可以使光栅方向始终与每段倾斜波导的纵向方向平行，而基本光栅是均匀的。因此，可以等效实现所需的CWG，并补偿弯曲波导中倾斜光栅引起的诸如反射布拉格波长偏移和反向模式转换等光响应。结果表明，CSBG-TW的采样结构为微尺度，以四段倾斜波导的CSBG-TW为设计目标与CWG之间的反射强度差异小于0.1 dB。与CWG相比，CSBG-TW便于全息曝光且波长可精确控制。因此，CSBG-TW可用于各种需要改变传播路径的光子集成器件中。
