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.

非线性光信号的电调制对于通信和光子电路中的新兴应用至关重要。然而，目前调制二阶光学磁化率的方法涉及间接且低效地改变三阶磁化率。在这里，我们表明单层二碲化钼晶体结构的电转换可用于直接调节二级磁化率。这种方法导致二次谐波产生的调制具有 1,000 的开/关比和 30,000% 每伏的调制强度，以及 300 nm 的宽带操作。我们还表明，由于电致异质结构，二碲化钼双层表现出相反的调制趋势。