🔬 Laser Linewidth and Bandwidth Calculator
Convert a laser’s spectral linewidth between wavelength units and frequency bandwidth.
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Linewidth-to-Bandwidth Conversion
A laser’s spectral purity can be specified either as a wavelength spread (Δλ) or an equivalent frequency bandwidth (Δν). The two are related through the speed of light by Δν = cΔλ / λ2, where λ is the laser’s center wavelength.
This relationship comes directly from differentiating c = λν. Because it depends on 1/λ2, the same wavelength linewidth corresponds to a much larger frequency bandwidth at shorter wavelengths than at longer ones. Use this for general optics reference and comparison.
Last reviewed August 2026