Direct electrical modulation of second-order optical susceptibility via phase transitions

Electrically induced transitions between hexagonal and monoclinic phases of molybdenum ditelluride can be used to make a second-harmonic-generation modulator with an on/off ratio of 1,000 and a broad bandwidth. Electrical modulation of nonlinear optical signals is crucial for emerging applications in communications and photonic circuits. However, current methods of modulating the second-order optical susceptibility involve indirectly and inefficiently changing the third-order susceptibility. Here we show that electrical switching of the crystal structure of monolayer molybdenum ditelluride can be used to directly modulate the second-order susceptibility. This approach leads to modulation of the second-harmonic generation with an on/off ratio of 1,000 and modulation strength of 30,000% per volt, as well as broadband operation of 300 nm. We also show that molybdenum ditelluride bilayers exhibit opposite modulation trends due to electrically induced heterostructures.

Automated summary

This research reveals that electrically induced transitions between hexagonal and monoclinic phases of molybdenum ditelluride can be used to directly modulate the second-order susceptibility, enabling the fabrication of a second-harmonic-generation modulator with a high on/off ratio and broad bandwidth capabilities.