▎ 摘　　要

We report the infrared transmission measurement on electrically gated twisted bilayer graphene. The optical absorption spectrum clearly manifests dramatic changes such as the splitting of the interlinear-band absorption step, the shift of the inter-van Hove singularity transition peak, and the emergence of a very strong intravalence (intraconduction) band transition. These anomalous optical behaviors demonstrate consistently a nonrigid band structure modification created by ion-gel gating through layer-dependent Coulomb screening. We propose that this screening-driven band modification is a universal phenomenon that persists to other bilayer crystals in general, establishing electrical gating as a versatile technique to engineer band structures and to create different types of optical absorptions that can be exploited in electro-optical device applications.