We present a comparative study of lateral and L-shaped PN junction Si optical phase shifters for Mach–Zehnder modulators in Si photonics based on TCAD simulation. First, we introduce an easy fabrication method for L-shaped PN junctions by inverting dominant dopant type in Si. Then, we present the quantitative comparison of Si optical phase shifters. The L-shaped PN junction device shows the larger modulation efficiency of VpiL and the lower optical phase shifter loss compared to the lateral one. The VpiL for the vertical one is 0.89 Vcm, nearly half that of the lateral one, 1.76 Vcm at the same optical phase shifter loss, 10.5dBcm⁻¹. Finally, taking advantage of single-drive configuration and optimizing input characteristic impedance, the large-signal simulation with 1mW input power and a 500μm phase shifter shows the dynamic optical modulation amplitude of 0.22mW for the vertical one, which could be a promising solution for a compact device footprint without a traveling wave electrode.

我们基于 TCAD 模拟对用于硅光子学中的马赫-曾德调制器的横向和 L 形 PN 结硅光学移相器进行了比较研究。首先，我们介绍了一种通过反转 Si 中的主要掺杂剂类型来制造 L 形 PN 结的简单方法。然后，我们介绍了 Si 光学移相器的定量比较。与横向器件相比，L 形 PN 结器件显示出更高的VpiL调制效率和更低的光移相器损耗。垂直的VpiL为 0.89 Vcm，几乎是横向的一半，在相同的光移相器损耗下为 1.76 Vcm，10.5dBcm ^-1. 最后，利用单驱动配置和优化输入特性阻抗，1mW 输入功率和 500 μm 移相器的大信号仿真表明，垂直光调制幅度为 0.22mW，这可能是一种很有前景的方法。无需行波电极的紧凑型设备占用空间的解决方案。