Patent ID: 8463097

Claim:
A method of designing a wave propagation circuit for obtaining a output field from an input field, the method comprising: a refractive-index-distribution initialization step of storing initial values of a refractive index distribution of a propagation medium in the wave propagation circuit, in storage means of a computer; a step of setting any position of the propagation medium in a wave propagation direction thereof, as an optimized position; an optimized-position input/output-field computation step, performed by the computer, of computing a first field, in a case where the input field has propagated forward from an inlet of the wave propagation circuit to the optimized position, and a second field, in a case where the output field has propagated backward from an output of the wave propagation circuit to the optimized position, and then storing the first and second fields in the storage means of the computer; and a refractive-index-distribution alteration step, performed by the computer, of adjusting the refractive index distribution at the optimized position so that wavefronts of the first field and the second field agree; the optimized-position setting step, said optimized-position input/output-field computation step and said refractive-index-distribution alteration step being iterated while the optimized position is being changed in the wave propagation circuit, wherein adjusting the refractive index distribution at the optimized position comprises adjusting, at two points on a boundary between a core and a clad in the propagation medium, the refractive index distribution at the optimized position based on a phase difference between a forward propagation field and a backward propagation field, the forward propagation field being a field when the input field is propagated forward from the inlet of the propagation medium to the optimized position, and the backward propagation field being a field when the output field is propagated backward from the outlet of the propagation medium to the optimized position.