Abstract
Abstract There are many reports in the literature of bound states in the continuum (BICs) in systems with up–down mirror symmetry. Semiconductor-based technology requires bulk semiconductor substrates, which impose symmetry breaking in the vertical direction. In this paper, we explore the possibility of realizing BICs in a high refractive index subwavelength one-dimensional grating placed on a substrate with a refractive index that varies from 1 to almost the refractive index of the grating, while the refractive index above the grating is 1. We demonstrate that in gratings with broken up–down mirror symmetry not only symmetry-protected BICs can arise, but also Friedrich–Wintgen (FW) and interference-based (IB) BICs with diverging quality factors. The limit of the refractive index difference between the grating and the substrate supporting the BIC was found to be as little as 0.03. We also present a study of configurations composed of a finite number of grating stripes, with refractive indices corresponding to GaAs in the grating and Al-rich AlGaAs in the substrate. We demonstrate that such an all-semiconductor configuration enables Q-factors above 104 when composed of fewer than 20 periods and nearly exponential Q-factor growth with increasing numbers of grating periods. The results of this study pave the way for a new class of micro- and nano-optical cavities realised in standard all-semiconductor technology and relying on the high quality factor induced by BIC.
Highlights
The interaction of light and matter within subwavelength volumes is an important phenomenon in numerous branches of physics and technology, including light detectivity [1], stimulated emission in lasers [2], nonlinear optics [3], single-photon generation [4], observation of polariton–excitons [5], quantum electrodynamics, and others
We explore the possibility of realizing bound state in the continuum (BIC) in a high refractive index subwavelength one-dimensional grating placed on a substrate with a refractive index that varies from 1 to almost the refractive index of the grating, while the refractive index above the grating is 1
When the spectral width of the dissipative Fano resonance becomes infinitely narrow, its quality factor tends to infinity and the resonance becomes a bound state in the continuum (BIC) [11, 12]
Summary
The interaction of light and matter within subwavelength volumes is an important phenomenon in numerous branches of physics and technology, including light detectivity [1], stimulated emission in lasers [2], nonlinear optics [3], single-photon generation [4], observation of polariton–excitons [5], quantum electrodynamics, and others. This example compares the Q-factors of two finite configurations with parameters corresponding to true BIC and qBIC in infinite arrangement. It demonstrates the possibility of achieving a very high Q-factor in a finite allsemiconductor VN grating and shows a possible way of constructing current injection devices
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
