Abstract

Optical interconnects for highly parallel computer architecture require high density optical switch arrays with dimensions of 100 × 100 or larger. Previously reported integrated switch array designs have been limited to 8 × 8 waveguides.¹ While achieving high switching speeds and relatively low insertion losses, these switches are limited by long interaction lengths which lead to array dimensions of as long as 60 mm. Our switch design consists of two sets of parallel waveguides which intersect at right angles. The intersections are doped with a material to locally sensitize the region to the photorefractive effect. We have fabricated arrays based on standard Ti:LiNbO₃ technology, using iron as a photorefractive sensitizer. Interfering beams are used to write an index grating at the waveguide intersections. This grating can then be used to diffract a portion of a data beam into the crossing waveguide. The diffraction efficiency depends on the length of the interaction region. Thus, insertion loss is traded off against switch density. We have constructed arrays of 15 × 15 up to 50 × 50 waveguides in an active area of only 5 mm square.

© 1989 Optical Society of America