Integrated RGB Beam Combiner in Al2O3 Photonic Circuits with On-Chip Modulation for AR/VR Displays

Aluminum oxide is a promising material for visible-light integrated photonics due to its low optical loss and wide transparency window across the RGB spectrum. This work presents the design and experimental demonstration of an integrated RGB beam combiner for applications in AR/VR, holography, 3D displays, and autostereoscopic display systems. The device employs Mach–Zehnder modulators for individual color modulation and gratings for out-of-plane emission. The experimental results demonstrate independent RGB routing, far-field beam combining, and thermo-optic modulation with an extinction ratio of up to 6.3~dB, highlighting the potential of Al${}_2$O${}_3$ photonic integrated circuits for compact dynamic color control at the pixel level.