Design and fabrication of integrated-optic 8*8 star coupler

The design and fabrication of an integrated-optic 8*8 star coupler is described. The coupler consists of two fan-shaped channel waveguide arrays facing each other and a slab waveguide region located in between them. The coupler geometry was designed and optimised by using the beam propagation method (BPM). The coupler was fabricated on silicon substrate using high-silica planar lightwave circuit (PLC) technology. The device exhibits low loss (average excess loss alpha =1.42 dB) and good coupling uniformity (standard deviation sigma =0.49 dB), which agree quite well with the BPM simulations.