The present invention provides for an improved polarized-light detector device. The device comprises a photodiode having a first contact disposed on the backside of a light-sensing medium and a second contact disposed on the frontside of the light-sensing medium. A spin filter medium is disposed between the backside of the light-sensing medium and the first contact. The application of a magnetic field aligns the magnetic moments in the spin-filter medium to cause the device to discriminate between different polarizations of an optical signal. The polarization discrimination is affected by introducing a net magnetization into the spin filter medium, thereby allowing selected spin-polarized electrons to either be transmitted through the spin filter medium to the point of detection or deflected from further transmission. Additionally, the invention is embodied in a polarization-selective-light detector array and methods for discriminating a polarized optical signal and selective optical wavelength detection.