An optical sensor system is provided which can be used not only as an ordinary light source, but also to calculate an environmental parameter. Rear surface outgoing light (31) output from a rear surface (21) of a semiconductor laser (10) is used in a process of calculating an environmental parameter by control and arithmetic device (60) to, while front surface outgoing light (30) output from a front surface (20) is used in an application other than the calculation of the environmental parameter.