Photonic crystal filters for multi-band optical filtering on a monolithic substrate

Abstract

Many applications require the ability to image a scene in several different narrow spectral bands simultaneously. Conventional multi-layer dielectric filters require control of film thickness to change the resonant wavelength. This makes it difficult to fabricate a mosaic of multiple narrow spectral band transmission filters monolithically. We adjusted the spectral transmission of a multi-layer dielectric filter by drilling a periodic array of subwavelength holes through the stack. Multi-band photonic crystal filters were modeled and optimized for a specific case of filtering six optical bands on a single substrate. Numerical simulations showed that there exists a particular air hole periodicity which maximizes the minimum hole diameter. Specifically for a stack of SiO 2 and Si 3 N 4 with the set of filtered wavelengths (nm): 560, 576, 600, 630, 650, and 660, the optimal hole periodicity was 282 nm. This resulted in a minimum hole diameter of 90 nm and a maximum diameter of 226 nm. Realistic fabrication tolerances were considered such as dielectric layer thickness and refractive index fluctuations, as well as vertical air hole taper. Our results provide a reproducible methodology for similar multi-band monolithic filters in either the optical or infrared regimes.

Gyroid “srs” Networks: Photonic Materials Beyond Nature

“…We show how the use of the most advanced fabrication top-down methods and materials enables the realisation of gyroid structured materials with unit cell sizes from the UV to the IR wavelength regions (Figure 9a). these synthetic photonic gyroids exhibit new and enhanced optical and topological properties, for applications as filters, [19,33] high-sensitivity sensors, [124][125][126] on-chip chirooptical devices, [19,127,128] and quantum-optical devices. [129,130] The gyroid is a remarkable geometry which deserves further investigation and joint efforts between photonics, chemistry and biological research communities in order to explore its full potential.…”

“…The geometrical and optical properties of gyroids and their related morphologies make these photonic materials an excellent platform for the development of chiral photonic devices, such as beamsplitters, [19] filters or polarisers, [32,33] and a powerful platform for the study of novel photonic topological states. [34,35]…”

Targeted multispectral filter array design for the optimization of endoscopic cancer detection in the gastrointestinal tract

“…17,20,21 Using absorptive or interference techniques, the MSFA filters the spectrum of the incoming light detected on a pixel-by-pixel basis, with a mosaic of filters deposited pixel-by-pixel across the sensor. 3,22,23 Following demosaicking and interpolation, the full image cube, including spatial and spectral information, is retrieved in a single snapshot. 24 Targeting the spectral properties of the MSFA to a given application thus maximizes the spatial resolution 17,25,26 and is feasible from a manufacturing perspective, 27,28 suggesting potential to address the aforementioned clinical unmet needs of MSI.…”

“…An alternative snapshot solution uses a multispectral filter array (MSFA) atop an imaging sensor 17 , 20 , 21 . Using absorptive or interference techniques, the MSFA filters the spectrum of the incoming light detected on a pixel-by-pixel basis, with a mosaic of filters deposited pixel-by-pixel across the sensor 3 , 22 , 23 . Following demosaicking and interpolation, the full image cube, including spatial and spectral information, is retrieved in a single snapshot 24 .…”

Frequency range dependent topological phases and photonic detouring in valley photonic crystals

“…The utilization of frequency degree of freedom makes it possible to transfer and process signals at multifrequencies and increase the channel capacity of photonic devices [34][35][36][37]. Based on the frequency degree of freedom, many multiband devices such as multiband filters [38], multiband transceivers [39], multi-functional photonic crystal fiber splitters [40], are proposed.…”