Quasi-BIC-governed light absorption of monolayer transition-metal dichalcogenide-based absorber and its sensing performance

Abstract

The efficiency and bandwidth of an optical absorbing material, especially for the promising two-dimensional transition metal dichalcogenides (TMDCs) are critical to underpin advances in photonic and optoelectronic devices. In this work, we present a general method to manipulate the bandwidth of an absorber with high efficiency through coupling with the quasi-bound states in the continuum (quasi-BIC). We demonstrate this strategy by taking absorbing material monolayer TMDC coupled with the lossless symmetry-broken photonic crystal (PhC) slab. An optimal-efficiency TMDC-based absorber with over three orders of magnitude of bandwidth adjustment is realized, by simultaneously adjusting the structure asymmetry parameter of PhC slab and the locations of monolayer TMDC in the structure. Interestingly, the absorption bandwidth is tailored quadratically with the asymmetry parameter, which derived from the powerful physics of bound state in the continuum (BIC) in radiation engineering. Moreover, a superior-performance optical refractive index sensor is further designed. We demonstrate that our proposed method based on quasi-BIC structure can also effectively govern the sensing performance. Present work not only provides further insight into BIC physics, but also offers a promising strategy of smart engineering in active optical devices with the properties on demand.

Optical bound states in the continuum in periodic structures: mechanisms, effects, and applications

“…In a disturbed environment, the ideal BIC transforms into a quasi-BIC with an offset resonant wavelength while maintaining a fairly high Q factor. This unique property renders it highly applicable in various optical and photonic contexts [220–228] . Given the distinctive characteristics of topological polarization singularities within radiation fields, their utilization in sensing appears logical.…”

Label-Free Bound-States-in-the-Continuum Biosensors

“…Considering their advantages, hybrid structures are included in the design of BICs biosensors. In this section, some hybrid BICs biosensors are summarized, including hybrid metal-dielectric gratings [ 101 , 102 , 103 ] and metasurfaces [ 104 , 105 , 106 ].…”

“…Hybrid metasurfaces are also followed with interests. Figure 7 b shows a symmetry-broken metasurface composed of Si 3 N 4 and MoS 2 proposed by Wang et al [ 104 ]. Quasi-BICs were used to achieve maximum absorption through adjusting the asymmetric parameter of the units.…”

“…( a ) A sine-modulated silver grating coupled with the dielectric material OrmoCore. Hybrid-BIC occurs at the “avoiding cross” of SPP modes and photonic (PH) modes, and has infinite radiation quality Q r (reprinted with permission from [ 101 ], ©2020, Wiley-VCH GmbH); ( b ) a symmetry-broken BICs metasurface composed of Si 3 N 4 symmetry-broken metasurface and MoS 2 monolayer with excellent sensing ability of maintaining high FOM under different RIs (reprinted with permission from [ 104 ], © 2022, IOP).…”

Enhanced sensitivity of an all-dielectric refractive index sensor with optical bound state in the continuum

“…Despite the unsurpassed FOM, the major drawback of the dielectric sensors in comparison against the plasmonic ones is a noticeably (approximately five times) less sensitivity [24]. Nowadays, comparative analysis of dielectric sensors performance is already available in the existing literature [25,26]. Yet, to the best of our knowledge, there is no exhaustive theory providing a clear optimization procedure that would lead to the maximal sensitivity of a BIC sensor.…”