While this effect is observable in most LEDs (subject to variability), there are photodiodes specifically designed with much more consistent light sensitivity:

While this effect is observable in most LEDs (subject to variability), there are photodiodes specifically designed with much more consistent light sensitivity: http://www.ttelectronics.com/sites/default/files/download-files/OP905-906_1.pdf http://www.ttelectronics.com/sites/default/files/download-fi...