Nonlinear coupling in triangular triple-core photonic crystal fibers.

We report on a numerical analysis of the nonlinear coupling characteristics in triangular triple-core photonic crystal fibers (TTC-PCFs) by using coupled mode theory. The results show that the coupling of the TTC-PCFs exhibit more excellent power selectivity than that of the dual-core PCF and sharper optical switching and coupling-band with lower critical power are implemented in asymmetric TTC-PCF. By adjusting the parameters of the TTC-PCF structure and length, a coupling-band power controlled with better flatness will be obtained, in which more than 90% input power can be transferred. These results maybe offer a new possibility for application fields including optical switching, pulse shaping and pulse compressing.