Bernhardt Nils, Koshelev Kirill, White Simon J U, Meng Kelvin Wong Choon, Fröch Johannes E, Kim Sejeong, Tran Toan Trong, Choi Duk-Yong, Kivshar Yuri, Solntsev Alexander S
School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia.
Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany.
Nano Lett. 2020 Jul 8;20(7):5309-5314. doi: 10.1021/acs.nanolett.0c01603. Epub 2020 Jun 22.
Atomically thin monolayers of transition metal dichalcogenides (TMDs) have emerged as a promising class of novel materials for optoelectronics and nonlinear optics. However, the intrinsic nonlinearity of TMD monolayers is weak, limiting their functionalities for nonlinear optical processes such as frequency conversion. Here we boost the effective nonlinear susceptibility of a TMD monolayer by integrating it with a resonant dielectric metasurface that supports pronounced optical resonances with high quality factors: bound states in the continuum (BICs). We demonstrate that a WS monolayer combined with a silicon metasurface hosting BICs exhibits enhanced second-harmonic intensity by more than 3 orders of magnitude relative to a WS monolayer on top of a flat silicon film of the same thickness. Our work suggests a pathway to employ high-index dielectric metasurfaces as hybrid structures for enhancement of TMD nonlinearities with applications in nonlinear microscopy, optoelectronics, and signal processing.
原子级厚度的过渡金属二硫属化物（TMD）单层已成为一类用于光电子学和非线性光学的有前途的新型材料。然而，TMD单层的固有非线性较弱，限制了它们在诸如频率转换等非线性光学过程中的功能。在此，我们通过将TMD单层与一种谐振介电超表面集成，来提高其有效非线性极化率，该介电超表面支持具有高品质因数的明显光学共振：连续统中的束缚态（BIC）。我们证明，与承载BIC的硅超表面相结合的WS单层，相对于相同厚度的平坦硅膜上的WS单层，其二阶谐波强度增强了超过3个数量级。我们的工作提出了一条途径，即采用高折射率介电超表面作为混合结构，以增强TMD的非线性，应用于非线性显微镜、光电子学和信号处理。
