Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For K-12 Students · Bragg Mirror

Bragg Mirror for a light sail

Built for k-12 students learning it in middle or high school. Watch the idea come alive with plain-language steps and everyday examples — perfect for projects and homework. Simulate a light sail live below — adjust the inputs and watch it respond, right in your browser.

Bragg Mirror (DBR)Live

a mirror from interference

Controls

Presets

Layer pairs

High index n_H

Low index n_L

A distributed Bragg reflector stacks alternating quarter-wave layers of high and low index. Their reflections add up in phase over a band of wavelengths — the stopband — creating a mirror that can exceed 99.99% reflectivity, far better than metal. More layer pairs and higher index contrast deepen the reflectivity. Used in lasers, fiber gratings, and dielectric mirrors.

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Data Inspector

Peak reflectivity99.627%

Layer pairs8

Index contrast1.59

Stopband width160 nm

Governing equation

R = (\frac{n _{0} n _{H}^{2 N} - n _{s} n _{L}^{2 N}}{n _{0} n _{H}^{2 N} + n _{s} n _{L}^{2 N}})^{2} = (\frac{2. 3 ^{16} - 1.5 \cdot 1.4 5 ^{16}}{2. 3 ^{16} + 1.5 \cdot 1.4 5 ^{16}})^{2} = 99.627%

Reading this result: Each added pair multiplies the residual transmission, so reflectivity approaches 100% geometrically — a little more contrast buys many fewer layers.

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Frequently asked questions

Is this good for k-12 students?: Yes — this version of "Bragg Mirror for a light sail" is framed for k-12 students learning it in middle or high school. Watch the idea come alive with plain-language steps and everyday examples — perfect for projects and homework.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.