Enhancing deflection efficiency of resonant cavity light-emitting diodes integrating with metagrating via the internal absorption effect

Controlling the light-emitting direction is crucial for the application of micro light-emitting diodes in the display field. Resonant cavity light-emitting diodes (RCLEDs) integrating with metagrating can achieve efficient deflection functionality. In this work, we systematically investigate the impact of the number of TiO₂/SiO₂ pairs in the upper distributed Bragg reflectors (DBR) and spacing between the RCLED and metagrating on deflection efficiency using a three-dimensional finite-difference time-domain (3D FDTD) method. Compared to 2 and 5 pairs of TiO₂/SiO₂ in the upper DBR, a higher deflection efficiency is achieved with 3 pairs of TiO₂/SiO₂. This is because 3 pairs of TiO₂/SiO₂ can effectively constrain the divergence angles of RCLEDs while minimizing the re-reflection of the non-vertical light from the metagrating back to the metagrating, thereby ensuring that the non-vertical light is gradually absorbed within RCLED. In addition, the deflection efficiency exhibits periodic oscillations as the thickness of the spacer layer. When the thickness of the spacer layer is an even multiple of one-fourth of the wavelength, the deflection efficiency is enhanced. This is because an even-multiple-thickness spacer layer enables a significant portion of the non-vertical light reflected by the metagrating to reach the interior of RCLED, while simultaneously maximizing the prevention of the non-vertical light traveling from the RCLED toward the metagrating.