The possibility of using Bragg reflection in a cylindrical fiber to obtain lossless confined propagation in a core with a <i>lower</i> refractive index than that of the cladding medium is proposed and analyzed.
© 1978 Optical Society of America
Pochi Yeh, Amnon Yariv, and Emanuel Marom, "Theory of Bragg fiber," J. Opt. Soc. Am. 68, 1196-1201 (1978)