Moth-Eye Nanostructure Antireflection Simulator

Surface structure

Substrate Silicon (n=3.50)

Wavelength 550 nm

Nanocone height 220 nm

Array period 150 nm

⚠ Period ≥ λ/n — the array is no longer sub-wavelength. Light diffracts into scattered orders instead of seeing a smooth graded index, so the antireflection model breaks down.

Reflectance @ λ

–

Flat-surface baseline

–

Avg. R (visible)

–

Transmitted

–

How it works

Light meeting a flat interface between two materials reflects a fraction set by the Fresnel formula R = ((n₁−n₂)/(n₁+n₂))². A single quarter-wave coating cancels that reflection at one design wavelength via thin-film interference, but drifts badly off that wavelength. A moth-eye nanostructure — subwavelength cones tapering from substrate index down to air — instead builds a continuous, graded effective index that light sees as a smooth ramp rather than a sharp step, suppressing reflection broadband across the whole visible spectrum.

R(λ) = |r|², via transfer-matrix method
n_eff(z) = √( f(z)·n_sub² + (1−f(z))·n_air² )
f(z) = fill fraction of the cone at height z

Cone height — taller cones taper the index more gradually, extending the low-reflectance band to longer wavelengths (needs height comparable to λ/2n for full effect).
Array period — must stay below λ/n so the structure behaves as an effective medium rather than a diffraction grating; the warning shows exactly when that assumption fails.
Substrate — a bigger index step (e.g. silicon, n=3.5) starts from far higher bare reflectance, so nanostructuring buys a much bigger absolute gain than on glass.

This is the mechanism behind anti-glare phone glass, moth-eye corneal nanostructures that inspired it, and — closest to the article — nanotextured silicon solar cells, where cutting front-surface reflection directly raises the fraction of sunlight that reaches the absorbing layer.

Incident light Reflected Transmitted

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.

Reflectance across the visible spectrumflat vs. current structure