Design of photonic-crystal-modulated narrowband multichannel filters for visible light with high transmittance

In this study, we introduce a novel approach for achieving narrowband filters in hyperspectral imaging spectrometers. By embedding photonic crystals within distributed Bragg reflectors (DBRs), we create resonant structures. Through meticulous simulations, we optimize a four-layer DBR configuration, resulting in spectral channels with a 3 nm average FWHM and exceeding 99% peak transmittance. Our key innovation lies in using photonic crystals to modulate transmission. By introducing TiO2 periodic structures, we control the effective refractive index and there by tune transmission wavelengths. The method covers a 475-625 nm spectral range with exceptional transmittance. We also investigate incident light angle effects, revealing systematic shifts in transmission peak. Our design offers adaptability by adjusting DBR film thickness for defining operational ranges and selecting TiO2 cylinder radii for precise channel manipulation. Our approach simplifies fabrication and holds potential for cost-effective hyperspectral imaging filters.