Buydens L, Demeester P
Appl Opt. 1994 Jul 20;33(21):4792-800. doi: 10.1364/AO.33.004792.
By combining a binary phase grating and materials with a controllable absorption, it is shown theoretically that it is possible to modulate the light in a zero-order diffraction beam and that a high contrast level for the beam modulation can be obtained. The intensity of higher diffraction orders also changes, but it is calculated that high contrasts cannot be achieved for these higher-order beams with the active gratings that we examine. This specific modulator design that we use can be applied both for transmitted and for reflected light. Using the same ideas, one may build a beam-deflection device by varying the period of the grating by selectively changing the absorption levels in the grating. The deflection efficiency of the device can be improved compared with other designs by use of a grating with a reduced intensity of the nondeflected zero-order beam.
通过将二元相位光栅与具有可控吸收特性的材料相结合，理论上表明可以对零级衍射光束中的光进行调制，并且能够获得光束调制的高对比度。高阶衍射光的强度也会发生变化，但据计算，对于我们所研究的有源光栅，这些高阶光束无法实现高对比度。我们所采用的这种特定调制器设计既适用于透射光，也适用于反射光。运用相同的理念，通过选择性地改变光栅中的吸收水平来改变光栅周期，可构建一个光束偏转装置。与其他设计相比，通过使用非偏转零级光束强度降低的光栅，该装置的偏转效率可以得到提高。
