We present a silicon 2.5D Photonic crystal based CWDM (Coarse Wavelength Division Multiplexer) design, suitable for fabrication by lithography techniques. Particularly, a 3-channel, near-infrared wavelength range CWDM design has been achieved, with the wavelength spacing in accordance with ITU-T G.694.2 standards, i.e. 20 nm. A hexagonal lattice of holes-in-slab has been used for the design with a L-type drop waveguide. Plane wave expansion and FDTD methods were employed for the design.