Gaussian-Like Mode Field Generated in a Seven-Core Photonic Crystal Fiber for Low Loss Splicing by Air Hole Collapse Technique

Multicore photonic crystal fiber is an important research direction to realize high-power supercontiuum. We report two post processing methods based on air hole collapse technique to generate Gaussian-like mode field in a seven-core photonic crystal fiber (SCPCF) for low loss splicing. By heating and collapsing all air holes in the meantime, the mode field of SCPCF becomes more concentrated and the valleys between separated core modes become much flatter. Another method to generate Gaussian-like mode field is selectively collapsing the central air holes between the seven cores, which can form an integrated larger core. Theoretical simulation results are confirmed by experiment and both methods are used to decrease mode field mismatch between SCPCF and double clad fiber with splicing losses as low as 0.46 and 0.22 dB, respectively.