Active Beam Steering Enabled by Photonic-Crystal Surface-Emitting Laser.

Emitting light toward on-demand directions is important for various optoelectronic applications, such as optical communication, displaying, and ranging. However, almost all existing directional emitters are assemblies of passive optical antennae and external light sources, which are usually bulky and fragile and show unendurable loss of light power. Here we theoretically propose and experimentally demonstrate a conceptual design of a directional emitter, by using a single surface-emitting laser source itself to achieve dynamically controlled beam steering.

Association of different digital media experiences with paediatric dry eye in China: a population-based study.

Objective: To investigate the ocular surface effects of different digital media experiences in Chinese elementary school students.

Design: Population-based cross-sectional study was used.

Setting: 14 randomly selected primary schools in Yuhuatai District, Nanjing, China PARTICIPANTS: 2,694 students between 7 and 8-year-old.