This study demonstrates the use of photonic crystal directional couplers to separate light of wavelengths 1.31 and 1.55μm. The photonic crystal structure consists of InAlGaAs nano-rods arranged in square lattice. The coupling length of the light in the directional coupler at a wavelength of 1.31pm was designed to be four times greater than that at 1.55μm. This behavior helps in designing devices to split the two wavelengths. The devices are fabricated by e-beam lithography and conventional photolithography. The measurement results confirm that 1.31μm/1.55μm directional couplers can be realized in PC structures formed by nano-rods.