Nano-structured transmissive spectral filter matrix based on guided-mode resonances

Abstract

Background: In this work, a nanostructured guided-mode resonance filter matrix with high transmission efficiency and narrow bandwidth is demonstrated. The developed nano-filter arrays have various usages, e.g., combined with the CMOS image sensors to realize compact spectrometers for biomedical sensing applications. Methods: In order to optimize the filter performance, the spectral responses of filters with different structural parameters are carefully studied based on the variable-controlling method. A quality factor is carried out for quantitative characterization. Results: In this case, a high fill factor of 0.9 can strongly suppress sidebands, while buffer layer thickness can be adjusted to mainly control the bandwidth. The transmission peaks shift from 386 nm to 1060 nm with good linearity when periods vary from 220 nm to 720 nm. The incident angle dependence is simulated to be~1.1 nm/degree in ±30°range. The filters are then fabricated and characterized. The results obtained from both simulations and experiments agree well, where the filters with the period of 352 nm exhibit simulated and measured transmission peaks of 564 nm and 536 nm, the FWHM of 13 nm and 17 nm, respectively. In terms of metal material, besides aluminum, silver is also investigated towards optimization of the transmission efficiency. Conclusion: The transmission spectra of designed filters have high transmission and low sideband; its peaks cover the whole visible and near infrared range. These characteristics allow them to have the possibility to be integrated into image sensors for spectrometer applications.

Narrowband and high-transmissivity guided-mode resonance filter in the visible range

“…et al. : 26 max[nb,ns]≤|nbsinθinc−iλΛ|<nw,where nb is the buffer layer refractive index, ns is the substrate refractive index, nw is the refractive index of waveguide layer, and θinc is the angle of incident light. We take the central wavelength at 555.6 nm as an example for verification, and the range of wavelengths obtained from the calculation is 511 to 710.15 nm, which is consistent with the simulation results.…”

“…In 2019, a narrowband transmission-type filter that is continuously tunable from the visible to the infrared range was reported. 26 However, the transmittance at the center wavelength is only 70%, with a half-width of 25 nm, and the transmittance of the sidebands is ∼30%. In 2020, a filter integrated on a silicon substrate was reported.…”

“…Although these two filters exhibited high transmission peaks, they were not continuously tunable in the visible light range. In 2019, a narrowband transmission-type filter that is continuously tunable from the visible to the infrared range was reported 26 . However, the transmittance at the center wavelength is only 70%, with a half-width of 25 nm, and the transmittance of the sidebands is ∼30%.…”

Ultra-Narrowband High-Transmissivity Guided-Mode Resonance Filter Based on Dual Dielectric Film Structure and High Refractive Index Waveguide Layer

“…Wenze Wu et al designed a GMR matrix-based nanostructured transmission spectroscopy filter using a guided-mode resonance-type filter consisting of a metal grating, a SiO2 buffer layer, and a high-emissivity waveguide layer. They employed the surface plasmon excitation mode of 2 the metal grating, which was excited and coupled to the guided mode to achieve a low sideband sharp transmission peak of anomalous resonance, which was accompanied by a FWHM of 25 nm and a transmittance of only 70%, although his sideband was below 20% [30]. Guangyu Sun et al presented a tunable polarization-independent narrowband GMR filter that employed a 2D subwavelength aluminum grating in conjunction with a polymer-dispersed liquid crystal layer.…”