基于复用体全息光栅的光学相控阵放大级串扰优化

提高各通道输出光信噪比,进行了复用体全息光栅的优化设计研究。推导了适用于角度放大器的多路复用体光栅耦合波理论,并与单路耦合波理论进行了比较。针对复用体光栅中的串扰问题,研究了调整光栅结构参数优化串扰的规律,并进行了实验验证。研究结果表明:当相邻两路体光栅的布拉格角间隔小于二者角度选择半宽之和时,相互间串扰较强,必须使用多路耦合波理论描述复用体光栅中波的衍射行为。调整相邻路体光栅的矢量倾斜角间隔、减小光栅周期和增加光栅厚度都可以降低串扰,其中调整矢量倾斜角和光栅周期优化效果明显但会降低角放大率,增加介质厚度不影响角放大率但需要厚度增加数倍才有效。

Optimization of crosstalk in optical phased arrays amplifier stage based on multiplexing volume holographic grating

To improve angular amplification of optical phased array and the signal-to-noise ratio of every grating, multiplexing volume holographic gratings (MVHGs) are studied. Coupled wave theory of MVHGs for angular amplifier is derived and compared with Kogelnik coupled-wave theory. To reduce the crosstalk in MVHGs, the law of adjusting grating parameters and crosstalk optimization are discussed, validated and analyzed experimentally. The results indicate that when the Bragg angle interval between two adjacent VHGs is less than the sum of angular selectivity, crosstalk is serious and multiple coupled-wave theory is needed to describe the interaction between different VHGs. Adjusting vector slant angle, reducing the grating period and increasing the thickness of the media will all reduce the crosstalk MVHGs. Increasing vector slant angle interval and reducing grating period of adjacent VHG can reduce crosstalk significantly, but they will reduce the angular magnification. Medium thickness has to increase several times to weaken crosstalk, but this will not affect the angular magnification.