Transverse Asymmetry of the Index Modulation Profile in Few-Mode Fiber Bragg Grating

The transverse asymmetry of the index modulation profile in the asymmetric few-mode fiber Bragg grating (FM-FBG) was investigated. The transverse asymmetry of the index modulation profile will lead to mode conversion between modes with the different azimuthal orders, and this asymmetry is characterized by the attenuation coefficient alpha. We evaluated that the value of attenuation coefficient alpha was 0.2 mu m(-1), and grating amplitude chi was 2.8 x 10(-4) for FM-FBG inscribed by UV single-side illumination. We found that the optimized value of alpha was 0.16 mu m(-1), at which the maximum mode conversion efficiency of LP01-LP11 can be achieved. The results of this paper provide great potential application in few-mode fiber (FMF) devices and mode division multiplexing (MDM) optical communication.

Automated summary

The study examined the transverse asymmetry of the index modulation profile in the asymmetric few-mode fiber Bragg grating (FM-FBG), which results in mode conversion between modes with different azimuthal orders characterized by the attenuation coefficient alpha. The experimental results show that the evaluation of the attenuation coefficient and grating amplitude of FM-FBG can be achieved through UV single-side illumination. The optimized value of alpha was found to be 0.16 μm(-1) for maximizing the mode conversion efficiency of LP01-LP11.