A new optical mode of propagation is described, which is the natural eigenmode (supermode) of a fiber (or any optical waveguide) with two cospatial periodic gratings. The mode frustrates the backward Bragg scattering from the grating by destructive interference of its two constituent submodes (which are eigenmodes of a uniform waveguide). It can be used in a new type of spatial mode conversion in optical guides.
© 1998 Optical Society of America
Amnon Yariv, "Frustration of Bragg reflection by cooperative dual-mode interference: a new mode of optical propagation," Opt. Lett. 23, 1835-1836 (1998)