Abstract: The detection of ambient light on an optical touch-sensitive device is disclosed. For example, one disclosed embodiment comprises capturing an image of at least a portion of a display screen with a camera located within the display device, and determined if ambient light in the image is at an acceptable level for display screen operation. Then, a visual representation is displayed representing whether the ambient light level is acceptable for display screen operation.

Abstract: A first multi-quantum well structure 12 is formed on a GaAs substrate 10. The first multi-quantum well structure 12 is formed of an AlGaAs barrier layer and a GaAs well layer alternately laid one on the other to form a multi-quantum well. The GaAs barrier layer is not doped with an impurity. A second multi-quantum well structure 14 is formed on the first multi-quantum well structure 12. The second multi-quantum well structure 14 is formed of an AlGaAs barrier layer and a GaAs well layer alternately laid one on the other to form a multi-quantum well. The GaAs barrier layer is not doped with an impurity. Whereby a required electrode area can be smaller to thereby obtain higher detection sensitivity.

Abstract: An infrared photodetector comprising of a photoabsorption layer formed on a substrate comprising of a multiquantum well structure, and a diffraction pattern formed over the photoabsorption layer. The diffraction pattern has recesses whose planar shape contains curves. Accordingly, the infrared photodetector can be formed by the fewer patterning steps and can detect the infrared radiation efficiently.

Abstract: An infrared photodetector comprising of a photoabsorption layer formed on a substrate comprising of a multiquantum well structure, and a diffraction pattern formed over the photoabsorption layer. The diffraction pattern has recesses whose planar shape contains curves. Accordingly, the infrared photodetector can be formed by the fewer patterning steps and can detect the infrared radiation efficiently.