Skip to main content

Magneto-Optic Design Calculator

Calculate Faraday rotation, required crystal length, isolator performance, and estimate Verdet constants at different wavelengths.

The Faraday effect rotates the polarization plane of light passing through a magnetized medium by θ = V × B × L, where V is the material's Verdet constant, B is the applied field, and L is the crystal length. This rotation is non-reciprocal — it does not reverse on back-propagation — which is the basis of optical isolators and circulators. This calculator covers four design tasks using tabulated Verdet constants for TGG, TSAG, fused silica, BK7, SF-6, and SF-57 at 532, 632.8, and 1064 nm. Faraday Rotation computes θ for a given V, B, and L. Crystal Design finds the required crystal length to achieve a target rotation angle (45° for a standard isolator) at a specified field. Isolator Performance reports isolation in dB and insertion loss from the actual rotation angle and polarizer extinction ratio. Verdet Dispersion estimates V at a new wavelength using the λ⁻² scaling approximation.

Input
Faraday Rotation
Rotation θ
-0.8000rad
Rotation |θ|
45.837°
Verdet constant used
-40.000rad/(T·m)
Abridged Optics — Magneto-Optic Design Calculator v1.0θ = VBL. Verdet dispersion uses λ⁻² approximation. Isolation: −10log₁₀(sin²Δθ). Data: TGG, TSAG from [1–4].

All information, equations, and calculations have been compiled and verified to the best of our ability. For mission-critical applications, we recommend independent verification of all values. If you find an error, please let us know.