Once light is coupled to a photonic chip, its efficient distribution in terms of power splitting throughout silicon photonic circuits is very crucial. We present two types of 1 × 4 power splitters with different splitting ratios of 1:1:1:1 and 2:1:1:2. Various taper configurations were compared and analyzed to find the suitable configuration for the power splitter, and among them, parabolic tapers were chosen. The design parameters of the power splitter were determined by means of solving inverse design problems via incorporating particle swarm optimization that allows for overcoming the limitation of the intuition-based brute-force approach. The front and rear portions of the power splitters were optimized sequentially to alleviate local minima issues. The proposed power splitters have a compact footprint of 12.32 × 5 μm2 and can be fabricated through a CMOS-compatible fabrication process. Two-stage power splitter trees were measured to enhance reliability in an experiment. As a result, the power splitter with a splitting ratio of 1:1:1:1 exhibited an experimentally measured insertion loss below 0.61 dB and an imbalance below 1.01 dB within the bandwidth of 1,518–1,565 nm. Also, the power splitter with a splitting ratio of 2:1:1:2 showed an insertion loss below 0.52 dB and a targeted imbalance below 1.15 dB within the bandwidth of 1,526–1,570 nm. Such inverse-designed power splitters can be an essential part of many large-scale photonic circuits including optical phased arrays, programmable photonics, and photonic computing chips.

中文翻译：

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逆向设计的锥度配置，用于增强集成的 1 × 4 硅光子功率分配器


一旦光耦合到光子芯片上，它在整个硅光子电路中的功率分配方面的有效分配就非常关键。我们提出了两种类型的 1 × 4 功率分配器，它们具有不同的分配比，分别为 1：1：1：1 和 2：1：1：2。对各种锥度配置进行比较和分析，以找到适合功率分配器的配置，其中选择了抛物线锥度。功率分配器的设计参数是通过结合粒子群优化来解决逆向设计问题来确定的，从而克服了基于直觉的蛮力方法的局限性。功率分配器的前部和后部依次进行了优化，以缓解局部最小值问题。所提出的功率分配器具有 12.32 × 5 μm2 的紧凑占地面积，可以通过与 CMOS 兼容的制造工艺制造。在实验中测量了两阶段功率分配器树以提高可靠性。结果，分路比为 1：1：1：1 的功率分配器在 1,518–1,565 nm 的带宽内表现出低于 0.61 dB 的实验测量插入损耗和低于 1.01 dB 的不平衡。此外，分路比为 2：1：1：2 的功率分配器在 1,526–1,570 nm 的带宽内显示出低于 0.52 dB 的插入损耗和低于 1.15 dB 的目标不平衡。这种逆向设计的功率分配器可以成为许多大规模光子电路的重要组成部分，包括光学相控阵、可编程光子学和光子计算芯片。