An exemplary embodiment of the present disclosure provides a wake up method and an optical input device using the same. The method includes generating sampling sets based on sampling signals of a modulated signal, and determining a sampling set from the sampling sets. A first light channel is defined in the light pipe. The actions may include discarding the output of the scan executed across a dynamic migration and repeat the scan. In other words, the bulges are not fastened to the side wall but are part of it.