Calculate spectral linewidth from coherence length or vice versa.
Spectral Parameters
nm
Calculation Results
Enter parameters to calculate linewidth
Quick Reference
ΔνFrequency linewidth
L_cCoherence length
ΔλWavelength linewidth
cSpeed of light
Overview
Laser linewidth is the width of the optical spectrum of a laser. It is inversely related to the coherence length—the distance over which the laser light remains in phase. Narrow linewidth lasers are essential for holography, spectroscopy, and fiber optic sensors.
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Pro Tips
Δν and L_c are related by the speed of light: Δν = c / (π * L_c) for a Lorentzian profile.
The narrower the linewidth, the longer the coherence length.
L_c = c / (π Δν) for Lorentzian, or L_c = c / Δν for rectangular spectra.
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Fun Facts
"Most common laser pointers have a coherence length of only a few centimeters, while high-end ultra-stable lasers can have coherence lengths exceeding 1,000 kilometers!"
"The LIGO gravitational wave detector uses lasers with extremely narrow linewidths to detect vibrations smaller than the width of an atom."
"Expanding the universe actually increases the linewidth of distant starlight, a phenomenon known as redshift broadening."
