Dynamic Tunable Optical Narrowband Filter of Multinanopore Array Based on Continuum Bound States

This study proposes and verifies an innovative design scheme of chip-level tunable optical filters based on continuum bound states (BIC). By constructing a photonic crystal waveguide structure with a periodic circular air hole array, the formation mechanism and regulation law of BIC were systematically revealed. On this basis, a new type of free-space transtransmission amplitude modulation filter with a composite structure of lithium niobate (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{LiNbO}_{3}$</tex>) thin film and indium tin oxide (ITO) was successfully developed. This device demonstrates breakthrough performance at the characteristic wavelength of 543 nm in the visible light band (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$500-600 \text{nm}$</tex>): it achieves a guiding mode resonance effect with a quality factor as high as <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{\wedge} 3$</tex> while maintaining a background transmittance of over <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{9 8 \%}$</tex>. Through three-dimensional finite-difference time-domain numerical simulation, the dynamic characteristics of electro-optic regulation in the multi-resonance mode were deeply analyzed, and the effective modulation ability of voltage regulation for the photon local field was confirmed. Experimental tests show that under the action of a bias voltage of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 10 \mathrm{V}$</tex>, the characteristic wavelength of the device can produce a controllable spectral shift of 0.48 nm. This porous array structure based on the BIC mechanism innovatively integrates high <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{Q}$</tex> value resonance and wide-spectrum background transmission characteristics. Combined with a composite control scheme of ferroelectric materials and transparent conductive oxides, it provides a new technical path for the development of miniaturized and low-power photonic integrated modulator devices, and has important application prospects in fields such as spectral imaging, optical sensing, and on-chip optical interconnection.