Coupling characteristics of three-core photonic crystal fiber couplers

The coupling characteristics of a three-core photonic crystal fiber (PCF) and its application as a broadband directional coupler are investigated. Numerical investigations demonstrated that broadband directional coupling with spectral width as large as 425nm and polarization-dependent loss lower than 0.06dB could be achieved in the proposed fiber coupler. In addition, the proposed fiber shows large tolerance to the variation of the fiber parameters. In particular, the fiber allows at least 4% deviation of the air-hole diameters and 10% deviation from the proposed length of 27mm.