A Novel WDM Component Based on a Three-Core Photonic Crystal Fiber

A novel 1.31/1.55 $mu$ m wavelength-division demultiplexer based on a three-core photonic crystal fiber is proposed. The fiber is composed of a large central core and two up-doped cores with different core sizes. The large core is realized by the omission of seven airholes and the insertion of a down-doped rod in the center of fiber. The effective indexes of the two small cores are index matched with the large core at the wavelength of 1.31 and 1.55 $mu$m, respectively. Therefore, wavelength dependent coupling is realized in the three-core optical fiber. Numerical investigation demonstrates that crosstalk lower than ${-}30$ dB and polarization-dependent loss lower than 0.1 dB can be realized in one such fiber with a length of 22 mm.