Apple recently registered a patent to integrate Horizontal Cavity Surface Emission Lasers (or HCSEL) into its next iPhone and Apple Watch. Placed under the screen, this optoelectronic device will open new doors for Apple devices, starting with an improved camera, like the LiDAR of the iPhone 13 Pro used for focusing.
HCSEL laser linked with multiple features
The HCSEL will also make Face ID and Touch ID functions more secure, and can collect precise metric data from the environment for better augmented reality experiences. Finally, this laser could even detect certain materials in the air to literally analyze the quality of the air. Source: Patently Apple