For guiding light on a chip, it has been pivotal to use materials and process flows that allow low absorption and scattering. Based on subwavelength gratings, here, we show that it is possible to create broadband, multimode waveguides with very low propagation losses despite using a strongly absorbing material. We perform rigorous coupled-wave analysis and finite-difference time-domain simulations of integrated waveguides that consist of pairs of integrated high-index-contrast gratings. To showcase this concept, we demonstrate guiding of visible light in the wavelength range of 550–650 nm with losses down to 6 dB/cm using silicon gratings that have a material absorption of 13,000 dB/cm at this wavelength and are fabricated with standard silicon photonics technology. This approach allows us to overcome traditional limits of the various established photonics technology platforms with respect to their suitable spectral range and, furthermore, to mitigate situations where absorbing materials, such as highly doped semiconductors, cannot be avoided because of the need for electrical driving, for example, for amplifiers, lasers and modulators.

为了在芯片上引导光，使用允许低吸收和散射的材料和工艺流程至关重要。基于亚波长光栅，我们在此证明，尽管使用强吸收材料，但仍可以创建传播损耗非常低的宽带多模波导。我们对由多对集成高折射率对比度光栅组成的集成波导进行严格的耦合波分析和有限差分时域模拟。为了展示这一概念，我们演示了使用硅光栅引导 550–650 nm 波长范围内的可见光，损耗低至 6 dB/cm，硅光栅在此波长下的材料吸收率为 13,000 dB/cm，并由标准硅制成光子技术。这种方法使我们能够克服各种已建立的光子技术平台在适当光谱范围方面的传统限制，此外，还可以缓解由于需要电驱动而无法避免使用吸收材料（例如高掺杂半导体）的情况，例如，用于放大器、激光器和调制器。