Correction: Cheng et al. Grating Couplers on Silicon Photonics: Design Principles, Emerging Trends and Practical Issues. Micromachines 2020, 11, 666

In the original publication [1], there was a mistake in Equation (8) as published. Given the angle definition in the publication, “$\cos \theta$” in Equation (8) should be “$\sin \theta$”. The corrected Equation (8) is shown below.

The authors apologize for any inconvenience caused and state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.