Long-Period Grating Based Coupler for Multi-Core Fiber Systems

In this work, we propose and demonstrate numerically a long-period grating (LPG) based technique to couple light from single-mode fiber (SMF) all cores of multi-core (MCF), i.e., an SMF MCF coupler. The launched into the core is coupled cladding due LPG inscribed in core. Then, optical power transferred between fibers claddings, enhanced by reduction radius. Finally, distributed identical LPGs them. We use coupled-mode theory study design proposed device. achieve coupling efficiency approximately 90% input total length 15.1 cm. also coupler's sensitivity radius period. Results show that device can improve pumping amplifiers.