Effective Area Enlarged Photonic Crystal Fiber with Quasi-Uniform Air-Hole Structure for High Power Transmission

Abstract

We investigate the potential of photonic crystal fiber (PCF) to realize high quality and high-power transmission. We utilize the PCF with a quasi-uniform air-hole structure, and numerically clarify that the quasi-uniform PCF can realize the effective area (A_eff) of about 500 μm² with bending loss comparable with that of a conventional single-mode fiber for telecom use by considering the quasi single-mode transmission. We then apply the quasi-uniform PCF to kW-class high-power beam delivery for the single-mode laser processing. The cross-sectional design of the PCF with the high-power delivery potential of more than 300 kW·m is numerically and experimentally revealed. A 10 kW single-mode beam at 1070 nm is successfully delivered over a 30 m-long optical fiber cable containing a fabricated PCF with single-mode class beam quality of M² = 1.7 for the first time.