| 摘要 |
The invention relates to phase matched optical gratings for performing signal multiplexing and demultiplexing in optical communications networks. In prior art gratings there is a phase linearity error between the grating line and the outputs on the focal line, comparing the center output to the surrounding outputs. This corresponds to a relative phase difference between each output which limits the passband. In the case of the AWG this degradation comes primarily from field aberrations in the output star coupler. The present invention has found that if the grating line of the optical grating is disposed on a ellipse instead of a circular arc, while the focal line of outputs defines a substantially circular arc, an optimum can be found where the phase linearity error is substantially eliminated, and all outputs have substantially the same phase. As a result, this creates substantially uniform passbands across the WDM spectrum. |
