Altering properties of lightguiding devices by trimming/tuning.

We present a formula connecting the change in the output of a multiple-channel waveguide to a micron-scale alteration in the physical properties of a segment of the waveguide. The analysis is motivated by the need to “tune” the properties of photonic devices after fabrication, necessitated by the present impossibility of fabrication to within the severe tolerances required to produce desired output characteristics. The results point to a method by which tuning can be carried out in an optimal manner. Example device application is illustrated by use of a simulation program. [ABSTRACT FROM AUTHOR]