| 摘要 |
The invention relates to a diffractive grating element arranged to be divided into at least two different grating regions (BGleft, BGright; MBGleft, MBGright) each having different diffractive properties and arranged on opposite sides respect to the transition point (TP) to form a splitted grating structure (SG). The diffractions generated by said at least two different grating regions are arranged to mutually compensate for the variation in the input angle (Theta) of the incident light wave (W) to the total diffraction efficiency of the at least one diffracted light wave that is arranged to propagate within said substrate.
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