Fig. 4
From: Anderson light localization in biological nanostructures of native silk
Interrogation of localization by external illumination. a Schematic of optical transmission matrix (TM) measurements. External point-like illumination (inset: focal spot with a diameter ~1 µm) is scanned on the array of the input α–β plane (IP) and non-vanishing optical intensity through modes is imaged on the output x–y plane (OP). b T a (α, β) map of the silk cocoon. The bottom projection image visualizes a small number of transmissive channels. Inset: probability distributions of s a for the cocoon specimen (black dots and var(s a ) = 0.5) and the paper specimen (red dots and var(s a ) = 5.2 × 10−3). c s ba (x, y) maps from two locations of Δ and ◊ in b. Inset: probability distributions of s ba from 104 translations of illumination for the cocoon (black dots) and paper (red dots) specimens. d, e TMs around two locations of Δ and ◊ in b. Each column of TM is composed of T ba (x, y), recorded at a position of (α, β). f, g s ba (x, y) overlay (pseudo-colour) on white-light microscopy images (greyscale). Fluctuations with a sharp field peak (FWHM ~740 nm) are located on the stacks of multiple silk fibres (Supplementary Fig. 7). The boundaries of filaments are marked by the coloured lines
