The study of strong field-driven nonlinear responses from high harmonic generation (HHG) in two dimension (2D) materials has been recognized as a valuable tool for probing ultrafast electron dynamics in the condensed matter systems. The laser polarization dependence of HHG in solids provides significant scientific insights into the crystal and band structure of the generation medium. In this work we experimentally investigate the impact of HHG in MoS2 monolayer by changing the laser polarization from linear to circular for different orientations relative to the symmetry axes of the crystal. The polarization analysis of harmonic emission reveals ellipticity and helicity dependent enhancement of even order harmonics which is strongly asymmetric near the symmetry directions of the crystal.
Bound states in the continuum (BICs) represent dark modes trapped in the radiation continuum. BICs received significant attention in optics and photonics as a simple tool to achieve giant quality factors by transforming them into quasi-BICs. Here, we report the observation of high-harmonic generation in dielectric metasurfaces hosting BICs. The metasurface is composed of a square lattice with parallel Si bars of a slightly different width placed on a transparent substrate. The structure is engineered to support a quasi-BIC in the mid-IR with a high quality factor. We tune the metasurface asymmetry to enable the optimal coupling condition that provide the highest high-harmonic generation efficiency. In the experiment, we demonstrate the generation of odd optical harmonics from the 3rd to the 11th order in the BIC regime and study their polarization dependence. We measure the dependence of the high-harmonic signal on the input intensity. The concept of metasurfaces with highly localized light boosted by BIC resonances provides a new degree of freedom to control experimentally strong nonlinear optical response.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.