Simulating neural synapses in the brain is a key step to realize the next generation computer, brain-like neuromorphic computing system. To mimic the plasticity of neural synapses by photons and develop all-optical artificial synaptic devices, we carried out an experimental study on the chalcogenide amorphous semiconductor artificial synaptic device based on the controllable light-induced inhibition. The control of material chemical composition and pumping optical power on the artificial neural synapse was studied, and the plasticity of the artificial neural synapse was described. The results show that the As-S planar waveguides with different impurities have different light-induced inhibition processes, and different pumping optical powers correspond to different suppression depths. Based on these characteristics, the artificial neural synapse reflects the short-term plasticity (STP), long-term plasticity (LTP), as well as paired-pulse facilitation (PPF), demonstrating it has good plasticity.