English
Second harmonic generation (SHG), as an important nonlinear optical effect, has gradually shifted its research trend towards the integration and miniaturization of photonic and optoelectronic on-chip devices in recent years. Two dimensional layered materials (2DLM) have opened up a new research paradigm in nonlinear optics due to their large second-order magnetization, atomically thin structure, and perfect phase matching. However, 2DLM faces the bottleneck of weak second harmonic conversion efficiency limitation due to the short interaction length between light and matter at the nanoscale. In addition, the advancement of integrated on-chip SHG devices based on 2DLM relies on the continuous development of novel strategies with tunable and efficient SHG response. Here, this review provides a comprehensive overview of the latest developments in exploring efficient and adjustable SHG responses in 2DLM. Various modulation and enhancement strategies for the frequency doubling response of two-dimensional optical modulators have been widely studied and systematically discussed, which can be divided into two categories: symmetry breaking and enhancement of light matter interactions. In addition, the challenges and prospects of further expanding and implementing 2DLM in nonlinear on-chip integrated devices with SHG modulation and enhancement characteristics were discussed.
