Frequently Asked Questions

An LPFG has a much longer grating period, which couples light from the fiber core into cladding modes instead of reflecting it back down the core. LPFGs operate purely in transmission — there is no reflected signal, unlike a standard FBG.

It makes LPFGs well suited as optical filters in systems that are sensitive to back-reflections, where even a small reflected signal from a standard FBG could cause problems.

Yes — a pair of 50% LPFGs can be combined to form an in-fiber Mach-Zehnder interferometer. LPFGs written in birefringent fiber can also work as polarization-dependent absorbing spectral filters.