In the retina, there are photoreceptor cells that take in light and emits excitatory signals to other cells in the retina that then do some basic pattern recognition and send the signal to the brain (Some of this pattern recognition is re-done in the brain but that's not really relevant in this instance).

You can excite neurons by giving them electric pulses via electrodes.

Some people are blind because their photoreceptor cells can't convert light into electric pulses (Retinitis pigmentosa). These people can be helped by artificial implants that do this conversion step, like the one proposed here. The device is split into little compartments and when light reaches one of them, the compartment converts the light into an electric signal, with an electric contact right on the cell. There seems to be no amplification involved, it's only living from the energy of the light. The tissue then gets that signal and processes it as vision. Cool, isn't it?

Disclaimer: not an expert, so correct me if I'm wrong.