Optical sensors containing reduced amounts of cross talk, as well as methods for making and using such sensors are described. The sensors contain a light absorption coating that is placed on a portion of the external surface of the optical sensor near the detector. This absorption coating reduces the amount of cross talk by reducing the amount of light reflected inside a transparent package of the sensor. As well, the coating can also reduce the amount of ambient and/or stray light that enters the sensor. The coating adds little cost or complexity to the manufacturing process for the sensors, yet reduces the cross talk without substantially increasing the size of the sensor or without increasing any reliability risks. Other embodiments are also described.