| 摘要 |
A device including a combination of a waveguide and a grating arranged to provide a spectral reflectance. The grating has a plurality of diffractive features in a first region and in a second region such that in the first region, a local average of a length of a period of the diffractive features substantially increases with increasing distance from an origin, and in the second region, the local average of the length of the period of the diffractive features substantially decreases with increasing distance from an origin. The origin is located at an end of the device. |
