Bragg Mirror (DBR)

The best mirrors are not metal — they are stacks of transparent layers whose reflections add up in phase to beat 99.99% reflectivity.

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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How it works

A distributed Bragg reflector alternates quarter-wave layers of high and low refractive index. Across a band of wavelengths called the stopband, every reflection interferes constructively, producing near-perfect reflectivity that metal mirrors cannot match. More layer pairs and greater index contrast deepen it — the basis of laser mirrors, fiber Bragg gratings, and dielectric coatings.

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Frequently asked questions

Is this distributed Bragg reflector tool really free?▾

Yes. Bragg Mirror (DBR) runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.

Do I need to install anything?▾

No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.

Can I save or share my simulation?▾

Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.

How accurate are the results?▾

The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.