A Y-Branch Photonic Crystal Slab Waveguide with an Ultrashort Interport Interval

We fabricated two-dimensional photonic crystal slab Y-branch waveguides with different intervals between the two output ports and measured their light guiding characteristics. The field intensity distributions of the TE polarized wave modes are also calculated by means of a transfer matrix method. Both the theoretical and experimental results show that the minimum interval between the two output ports is about 1.4 times the transport wavelength of 1.55 μm. If the interval becomes smaller, light waves in the two branches will couple each other seriously. The result will be helpful for designs of ultracompact wave demultiplexers and all-optical integrated circuits.