We describe the properties of a surface-corrugated long-period-grating fiber taper fabricated using contact optical lithography and wet etching techniques. The preservation of cylindrical symmetry in this device facilitates investigation of the modal behavior. Comparison of the measured and calculated transmission spectra reveals that the widely used coupled-mode theory is not applicable. Instead, a mode-projection model, in which modal propagation and coupling are treated separately within the grating, explains the experiments very well.
© 2008 Optical Society of America
Fiber Optics and Optical Communications
Original Manuscript: January 4, 2008
Revised Manuscript: February 16, 2008
Manuscript Accepted: February 17, 2008
Published: March 31, 2008
W. Ding and S. R. Andrews, "Modal coupling in surface-corrugated long-period-grating fiber tapers," Opt. Lett. 33, 717-719 (2008)