Mode-coupling mechanisms of resonant transmission filters

Abstract

We study theoretically modal properties and parametric dependence of guided-mode resonance bandpass filters operating in the mid- and near-infrared spectral domains. We investigate three different device architectures consisting of single, double, and triple layers based on all-transparent dielectric and semiconductor thin films. The three device classes show high-performance bandpass filter profiles with broad, flat low-transmission sidebands accommodating sharp transmission peaks with their efficiencies approaching 100% with appropriate blending of multiple guided modes. We present three modal coupling configurations forming complex mixtures of two or three distinct leaky modes coupling at different evanescent diffraction orders. These modal compositions produce various widths of sidebands ranging from ~30 nm to ~2100 nm and transmission peak-linewidths ranging from ~1 pm to ~10 nm. Our modal analysis demonstrates key attributes of subwavelength periodic thin-film structures in multiple-modal blending to achieve desired transmission spectra. The design principle is applicable to various optical elements such as high-power optical filters, low-noise label-free biochemical sensor templates, and high-density display pixels.

Recent Advances in Resonant Waveguide Gratings

“…RWGs can theoretically reach 100% of reflection efficiency when their profile is vertically or horizontally symmetric or when integrated with quarter‐wave Bragg stacks . Recently, a high efficient narrowband transmission filter has been demonstrated with two crossed and strongly modulated RWGs and at normal incidence with partially etched single‐layer RWG . RWGs can also be utilized to make efficient wideband reflectors using a periodic array of high‐index scatterers on a low index layer (Figure b,c) .…”

“…[54] Recently, a high efficient narrowband transmission filter has been demonstrated with two crossed and strongly modulated RWGs [151] and at normal incidence with partially etched single-layer RWG. [152,153] RWGs can also be utilized to make efficient wideband reflectors using a periodic array of high-index scatterers on a low index layer (Figure 8b,c). [145,146] The bandwidth and the efficiency of the broadband reflectors with partially etched RWGs can be tuned with the grating depth, fill factor, the thickness of the homogeneous layer, and with The case (c) is at the exact resonance condition, and in the case (e) there is a strong transmitted first order that causes a decrease of the zeroth-order transmission.…”

Guided‐Mode Resonances in All‐Dielectric Terahertz Metasurfaces

“…For most practical applications, resonances with strong intensity and narrow linewidth are desirable. [8,[21][22][23][24][25][26][27][28][29][30][31] The GMR filter primarily comprises of a diffractive grating and an in-plane waveguide. However, most of the resonances are constrained by the trade-off between resonance intensity and linewidth.…”

“…[35] The 2D array of silicon cuboid resonators acts as a grating and more importantly, the silicon metasurface also acts as a homogeneous core layer that support slab waveguide modes, governed by total internal reflection (TIR) [36] (see Supporting Information for details). The combination of the waveguiding criteria (i.e., TIR) and the grating equation provides the critical condition for the realization of GMR, which is given by: n sin [8,[21][22][23][24][25][26][27][28][29][30][31][32][33]36] where Λ is the lattice period, λ is wavelength and the corresponding frequency is given by f = c/λ . The modes that lie above the light line are radiative in nature, while those lying below are guided within the slab waveguide.…”

Nanophotonic identification of defects buried in three-dimensional NAND flash memory devices

“…3e for λ = λ 2 and λ 3 , respectively. The fieldintensity distributions involving an enhancement factor of two to four inside the wordline clearly show vertical standingwave patterns that approximate classical TM 3 (λ 2 ) and TM 2 (λ 3 ) guided-mode resonances (GMRs) coupled through a dominant first-order diffraction process [31][32][33] . This GMR-like effect is produced by resonant excitation of the leaky-guided hyperbolic Bloch modes as they are the only propagating optical state in the W-SiO 2 multilayer.…”