Ultracompact and wideband power splitter based on triple photonic crystal waveguides directional coupler

Three single-mode photonic crystal waveguides (PCWs) are put together closely to construct three PCWs directional coupler (3PCWDC). It is found that the coupling coefficient of two even modes excited by the input field symmetrically entering 3PCWDC may be increased dramatically by reducing the size scales of dielectric rods between the neighbouring PCWs. The coupling length in this structure can be much shorter than that in conventional PCWs within the frequency range of interest. The application of this feature to an ultracompact, wide bandwidth and high-transmission power splitter is addressed. The simulation results by using the finite-difference time-domain method show that the structure exhibits new interesting characteristics.