Inverse designed photonic crystal de-multiplex waveguide coupler.

A two-dimensional photonic crystal diplexer integrated with a waveguide coupler is proposed. The design is computer generated through an inverse design process, limited within an area measuring 5 mumx5 mum. The best working device was designed for the optical communication wavelengths, 1.50 mum and 1.55 mum, i.e. a channel spacing of 50 nm. The device exhibits crosstalks suppressed below 40dB and coupling efficiencies close to 80%, for both channels.