High-Performance Quality Factor Based Sensor With Diagonal Cylinder Metasurface of the Bound State in the Continuum

Abstract

High-quality-factor (high-Q-factor) electromagnetic resonance plays an important role in sensor applications. Previously proposed gas refractive index sensors are often limited by the large cavity length or microscale fabrication process in practical applications. Recently, ultra-high Q factor resonance based on the bound state in the continuum (BIC) has provided a feasible approach to solve these problems. In this paper, we propose a metasurface structure consisting of a single size tetramer cylinder. It supports dual band toroidal dipole (TD) resonances driven by BIC. The physical mechanism of double TD resonances is clarified by the multipole decomposition of the metasurface band structure and far-field scattering power. The sensor structure based on this achieves a sensitivity of 518.3 MHz/RIU, and the maximum line width does not exceed 680 kHz. The high-Q-factor electromagnetic resonance has the advantages of polarization independence and simplicity to manufacture. These findings will open up an avenue to develop the ultrasensitive sensor in the gigahertz regime.

Recent Development in Metasurfaces: A Focus on Sensing Applications

“…Nevertheless, due to the mismatch between wavelengths and molecule sizes, the sensitivity for nanometer-scale and trace-amount analytes is relatively low. To control EM waves in the microwave, terahertz, and optical spectrums, MS—a device made up of several subwavelength nanoresonators—can be utilized [ 89 ].…”

Two Individual Super-Bound State Modes within Band Gap with Ultra-High Q Factor for Potential Sensing Applications in the Terahertz Wave Band

“…These unique features distinguish BICs from the traditional optical modes and significantly improve the performance of optical devices, especially for sensors, whose sensitivity is directly affected by the Q factor. In recent years, BICs were well explored in the literature for sensors in different structures, such as photonic crystals [ 7 , 18 , 19 ], metasurfaces [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ], and gratings [ 36 , 37 , 38 , 39 ]. These BIC sensors have different uses, for instance, refractive index sensing [ 7 , 25 , 28 , 30 , 36 , 39 , 40 ], biosensing [ 20 , 34 , 41 , 42 ], and gas detection [ 37 ], ranging from visible [ 37 ] to infrared [ 23 , 33 , 38 , 39 ] to THz [ 21 , 22 , 29 , 31 , 35 , 43 ] regions.…”