LAUSR

Due to the existence of surface plasmon resonances, enormous nonlinear optical effects are generated by plasmonic nanostructures, leading to the trend in which these nanostructures have gradually become ideal platforms for all‐optical manipulations. Here, it is discovered that an anomaly of the relationship between the sample reflectance and the pump‐light polarization angle occurs at the localized surface plasmons mode. Relatively, normal relationships exist at the interband transition and the propagating surface plasmon polaritons mode. Furthermore, electrical‐field enhancements are intentionally acquired by solely keeping either the pump beam or the probe beam on, so that the anomaly‐governing mechanism is identified as the aggregation of hot electrons within the probe‐detected sensitivity zone. The discovery of this anomaly and the associated mechanism can be applied to ultrafast all‐optical communications, computing, and the design of photonics‐related devices.