All‐Optical Coherent Control of Ultrafast Injection Photocurrent in Multilayer Rhenium Disulfide Under Two‐Color Light Excitation

Abstract Quantum coherence by electronic quantum interference (QI) is significant to generate macroscopic photocurrent without heterostructures in both bulk and low‐dimensional materials. However, the coherent injection photocurrent by QI in low‐dimensional materials can be veiled by other linear or nonlinear optical effects. Herein, the coherent ultrafast injection photocurrent is investigated by coherent terahertz (THz) wave generation in multilayer rhenium disulfide (ReS 2 ) at the nanometer scale under two‐color light excitation. It is observed that the THz radiation can be controlled by adjusting the relative phase between the two‐color lights under normal incidence. The experimental results demonstrate that the THz radiation of ReS 2 is ascribed to the injection photocurrent from the electronic coherence of QI effect. However, the injection photocurrent is veiled by the nonlinear polarization, shift current, and drift current under oblique incidence. A method is proposed to isolate the pure injection photocurrent from these optical responses, based on the THz amplitude dependences on the pump power, incident polarization angle, and the relative phase between the two‐color lights. This work not only provides an all‐optical non‐contact method for understanding the quantum photocurrent in ReS 2 but also promotes the quantum coherent control for solid‐state quantum devices.