Year: 2026
Type: preprint
Abstract: Inverse-designed spectral routers can enable compact snapshot spectral imaging by directing different wavelengths to designated detector sub-pixels without mechanical scanning or absorptive filters. Here, we examine how routing performance varies as the number of spectral channels increases while the visible bandwidth remains fixed. A delay-bandwidth analysis relates channel count, worst-channel efficiency, and device thickness, explaining the growing optical capacity required to generate many spatially distinct spectral outputs. We then use adjoint-based topology optimization and three-dimensional finite-difference time-domain simulations to design TiO2/SiO2 routers with 9, 16, 25, and 36 channels under matched material, bandwidth, and thickness conditions. The average routing efficiency increases with sub-pixel size and approaches a plateau, while the maximum near-plateau efficiency decreases monotonically from 97.0% for 9 channels to 82.3% for 36 channels. At a fixed channel count, compressing the wavelength spacing to 8 nm or rearranging the wavelength-to-sub-pixel assignment changes the efficiency by less than one percentage point. These results indicate that the observed efficiency penalty is governed mainly by the number of wavelength-dependent routing constraints rather than by wavelength spacing or local wavelength arrangement. The findings quantify the trade-off between spectral sampling and optical throughput in compact snapshot spectral imagers.
Source: arXiv (Cornell University)
Institution: Hanyang University
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funders: National Research Foundation, Hanyang University, Ministry of Culture, Sports and Tourism, National Research Foundation of Korea, Korea Creative Content Agency, Iran Telecommunication Research Center, Ministry of Science and ICT, South Korea, Samsung, Institute for Information and Communications Technology Promotion
Awards: G1767291611, G1816186749, G2124488252, G2199931666, G2365584765, G2424221239, G2581689735, G2805063684, G3363485770, G3812690899, G3904058931, G4248781092, G4848589832, G5068639314, G5396576536, G6098413186, G6107023710, G6451927723, G697327996, G7747912143, G7967031600, G7997132224, G8363210920, G8470340488, G8561082692
OpenAlex ID: W7171558549