Efficient multichannel integrated optics star coupler on silicon

The design and fabrication of a 19*19 star coupler suitable for lightwave distribution in high-capacity local area networks with a measured efficiency of 55% at a wavelength of 1.3 mu m is reported. The coupler consists of two arrays of channel waveguides separated by a slab waveguide fabricated on a silicon substrate using SiO/sub 2//Si technology. The integrated optics design is well suited to manufacture. It is argued that the coupler performance does not depend critically on the fabrication accuracy. In fact, the efficiency is primarily determined by the radiating element pattern, whose effective angular aperture is essentially determined by the width Omega of the first Brillouin zone, and, therefore, it is not greatly influenced by the fabrication process.<>