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.