= Fiber Bragg grating
= Fibre Bragg grating
{synonym}
A <fiber Bragg grating> is a longitudinally periodic <refractive index> modulation in an <optical fiber>. Reflections from successive periods reinforce near the vacuum <wavelength> $\lambda_B=2n_{\rm eff}\Lambda$, where $\Lambda$ is the period and $n_{\rm eff}$ is the guided mode's effective <refractive index>.
It acts as a wavelength-selective reflector while much off-resonant <light> continues through the <optical fiber>. Stretching the fiber changes the period and usually the effective <refractive index>, moving the reflected peak. This supports strain sensing; <temperature> also shifts the peak, so a strain measurement needs <temperature> control or independent compensation.
Back to article page
