A brightly lit smart phone display looks good, but drains the battery quickly. Much of this can be blamed on a screen component called a polarizer. Light points in all directions, which can be mathematically broken down into two parts that are perpendicular to each other. A polarizer allows only one of the two to pass through, which is required for liquid-crystal display (LCD) screens to work but wastes at least 50% of the light. In practice, most polarizers waste much more. In a study published this month in Optica, researchers report a newly designed polarizer with much higher energy efficiency. The scientists etched a 3D nanoscale pattern on a piece of silicon, which enabled the polarizer to interact with and manipulate light. When they shone infrared light through their polarizer, the pattern on the silicon allowed light in one direction to pass through and rotated its perpendicular counterpart by 90°, thereby letting it pass through as well. The researchers achieved a maximum polarizer efficiency of 74%, they report. The technique needs to be extended to visible light before it can be utilized in LCDs and extend devices' battery lives. But the team says that if it can optimize the approach, such displays could extend battery life and enable brighter screen settings in future smart phones.