Structure-based optical filtering by the silica microshell of the centric marine diatom Coscinodiscus wailesii

Abstract

Diatoms are a renewable (biologically reproducible) source of three-dimensional (3-D) nanostructured silica that could be attractive for a variety of photonic devices, owing to the wide range of quasi-periodic patterns of nano-to-microscale pores available on the silica microshells (frustules) of various diatom species. We have investigated the optical behavior of the silica frustule of a centric marine diatom, Coscinodiscus wailesii, using a coherent broadband (400-1700 nm) supercontinuum laser focused to a fine (20 µm diameter) spot. The C. wailesii frustule valve, which possessed a quasi-periodic hexagonal pore array, exhibited position-dependent optical diffraction. Changes in such diffraction behavior across the frustule were consistent with observed variations in the quasi-periodic pore pattern.

Interference patterns and extinction ratio of the diatom Coscinodiscus granii

“…Since diatoms are so widespread and biologically successful although they are not motile, the frustule presumably has some other biological advantage [4][5][6]. Even though well investigated, the functionality of the frustule is not fully understood but it has been shown that the frustule provides the diatom with several properties; protection from mechanical and biotic stress, efficient nutrition uptake and light harvesting properties [4,[7][8][9][10][11][12]. In this work, focus is on how monochromatic light is transmitted through the valve.…”

“…Alternatively, light can be transmitted through the valve with diffraction from the foramen (holes) as the important effect. We are interested in developing a simple description of the multiple interference points described in simulations at a distance corresponding to outside the frustule when light interacts with the valve of the centric species Coscinodiscus granii (C. granii) [10,[12][13][14][15]. These interference points have been discussed on a theoretical basis and a few have been showed experimentally [13][14][15][16][17].…”

Towards uniformly oriented diatom frustule monolayers: Experimental and theoretical analyses

“…diatoms, the exoskeleton surfaces include up to three layers of pore structures, with pore sizes ranging from 60 nm to 1 μm. These hierarchical, porous structures give rise to the diatom frustules' extraordinary mechanical strength 4 , enormous surface area 5 , and unique optical properties 6,7 .…”

“…Importantly, the ability to manipulate the frustules on a large scale, combined with simple arraying techniques 20 , may enable the development of practical, real-world applications using diatoms. However, despite the promise of the use of diatom frustules in a variety of areas, the unique properties of diatoms have typically only been studied on the scale of a single diatom frustule (requiring only individual diatom alignment) [6][7][8][10][11][12][13][14][15][16] or as bulk materials (requiring no significant alignment) 17 .…”

Comparing optical properties of different species of diatoms

“…Setting diatoms apart from other phytoplankton is the nanostructured silica shell surrounding the protoplasm, called the frustule unique for each of the over 200000 different species [2,3]. Even though well investigated the functionality of the frustule is not fully understood but it has been shown that the frustule provides the diatom with several properties; protection from mechanical and biotic stress, efficient nutrition uptake and light harvesting properties [4,[5][6][7][8][9][10]. In this work the focus how linear polarized monochromatic light is transmitted through the valve in air.…”