Two-dimensional amorphous photonic structure in the ligament of bivalve Lutraria maximum

Here we report a two-dimensional amorphous photonic structure (2D APS) discovered in the ligament of bivalve Lutraria maximum, based on scanning electron microscopy and fiber optic spectrometry combined with the image processing technology and pair correlation function analysis. This structure contains 70% in volume of parallel aragonite fibers embedded in a protein matrix. These fibers, in cross section, are hexagonal to polygonal with diameters of 194nm and are packed in short-range order with a nearest-neighbor distance of 202nm. Moreover, experimentally measured reflectance spectrum and theoretical predictions prove that this photonic structure gives rise to a golden structural color with the peak wavelength at about 650nm. We expect this unraveled structure may inspire the design and synthesis of a novel 2D APS.