In various embodiments, a simple, robust molybdenum disulfide (MoS2) based photosensor is provided that is able to detect both light intensity and wavelength. The MoS2 based photosensor may be structured as a field effect transistor (FET) with a back-gate configuration, including MoS2 nanoflake layers, an insulating layer coated, doped substrate, and source, drain and backgate electrodes. The photoresponse of the MoS2 based photosensor exhibits a fast response component that is only weakly dependent on the wavelength of light incident on the sensor and a slow response component that is strongly dependent on the wavelength of light incident on the sensor. The fast response component alone may be analyzed to determine intensity of the light, while the slow response component may be analyzed to determine the wavelength of the light.