A semiconductor device package includes a light-emitting device, a diffuser structure, a first optical sensor, and a second optical sensor. The light-emitting device has a light-emitting surface. The diffuser structure is above the light-emitting surface of the light-emitting device. The first optical sensor is disposed below the diffuser structure, and the first optical sensor is configured to detect a first reflected light reflected by the diffuser structure. The second optical sensor is disposed below the diffuser structure, and the second optical sensor is configured to detect a second reflected light reflected by the diffuser structure.