Ultra-Broadband Mode Converter Using Cascading Chirped Long-Period Fiber Grating

Abstract

We propose and demonstrate an ultra-broadband mode converter based on a cascade chirped long-period fiber grating (CLPFG) written in a two-mode fiber. The mode converter can convert fundamental mode (HE11even and HE11odd modes) into the first order cylindrical vector (CV) modes (TE01, TM01, HE21even and HE21odd modes). We design and analyze the mode conversion characteristics of this kind of grating in theory. The simulation results show a 10 dB bandwidth of 170 nm and 20 dB bandwidth of 145 nm can be achieved by optimizing the parameters of the CLPFG. In the terms of experiment, we achieve the broadband mode converter with 10 dB bandwidth of 170 nm from 1472 nm to 1642 nm.

Keywords

• Long-period fiber grating
• cylindrical vector mode
• mode converter
• ultra-broadband.