In the momentum space of bound states in the continuum (BIC), vortex configurations around the Γ-point are generated by the selection rules. The electric field distribution close to the BIC satisfies twofold rotational symmetry (C2). Since the periodic structure of 2D photonic crystals (PhCs) supports the generation of odd harmonics, this characteristic provides an attractive approach for generating high-harmonic optical vortex (OV) beams with both left and right handedness. Also, the topological charge of OV beams generated by C4v-symmetric PhCs can be further improved by an increase of structural symmetry. Moreover, since the nonlinear conversion efficiency of directly used PhCs is low, their practicability is limited. Here, a hexagonal arrangement of C6v-symmetric 2D PhCs slab is selected. Through energy band selection, higher order fundamental and nonlinear OV beams can be generated, which can not only cover the topological charge of the C4v-symmetric structure, but also generate more abundant topological charge. In addition, we improve the third-order nonlinear conversion efficiency by the mirror approach, which is 22 times greater than with the direct use of PhCs. This method can improve the channel capacity of OV generators based on BICs and make them more practical.
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.