title: Bandwidth control of long-period grating-based mode converters in few-mode fibers.
abstract: Control of the group-velocity differences between two distinct modes in a few-mode fiber can be used to define the spectral characteristics of long-period gratings written in them. Using this effect, we report the demonstration of strong mode conversion (>99%) with long-period fiber gratings over what is believed to be a record bandwidth of 63 nm. These novel spectra are obtained from gratings written in specially designed few-mode fibers in which the grating phase-matching condition is satisfied over a large spectral range. We show that the bandwidths of such mode converters can be tailored by suitably altering the design of the few-mode fibers. The polarization-dependent coupling for the mode converters varies by less than 0.004% over the entire spectrum.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Ramachandran
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Wang
authors.forename: Man
authors.initials: M
authors.lastname: Yan