High density multichannel optical waveguides with integrated couplers

Preferentially etched waveguides in Si grooves have a surface smoothness associated with the crystalline planes. The surface scattering loss can be minimized. The low index of refraction of the Si0₂ buffering layer permits an easier choice of waveguide materials. The input/output coupling surfaces simplify the coupling problems. The density of channel waveguides is limited both by photolithographic techniques and by throughput requirements. Waveguides with a 12.5 μm width and spacing can be fabricated with reasonable throughput. This gives more than 1000 channel waveguides in an inch.