DEVICE EQUIVALENCE IN INTEGRATED-OPTICS

The concept of device equivalence is introduced, In equivalent devices , the light propagation can be described by identically evolving modal expansions, resulting in identical power transfer ratios. By first ap plying this concept to a z-invariant structure with a low refractive-i ndex contrast it is shown how a normalized coordinate space can be def ined in which equivalent structures have exactly the same geometry, Su bsequently it is shown how this normalized coordinate space can be def ined for z-variant integrated optical devices, again provided that the lateral refractive-index contrast is small, This normalization makes it possible to perform numerical device simulations in normalized coor dinate space, the results being applicable to a large set of equivalen t devices, Furthermore, starting from a known design, it simplifies re designing that device for use at another wavelength or using other mat erials significantly, the resulting device being equivalent to the ori ginal one.