Twisting and bending characteristics of low-multimode LP21 mode propagation in optical fibers is presented for the first time. Theoretical fiber mode modeling, combining geometrical rotation with opto-elastic effects, demonstrates that the propagation of the LP21 mode is bending-effect-immune. Experimental testing verifies that the LP21 mode specklegram rotates 0.9112 of the fiber twist angle in a fused silica fiber, independent of any fiber bending. This characteristic allows for the LP21 mode to be highly applicable in fiber specklegram sensors.
© 2011 Optical Society of America
Fiber Optics and Optical Communications
Original Manuscript: August 8, 2011
Revised Manuscript: September 23, 2011
Manuscript Accepted: September 26, 2011
Published: October 28, 2011
Yufeng Yuan, George Wu, Xian Li, Yuqiang Fan, and Xingkun Wu, "Effects of twisting and bending on LP21 mode propagation in optical fiber," Opt. Lett. 36, 4248-4250 (2011)