It means to get activation when catalyst meets optic. In other words, If you transmit light, catalyst would take the energy of light and generate change of electron so that the electron make strong chemical action. In this time, the strong chemical action oxidize polluted things and make harmless substance.
These all process is named Optic Catalyst. Catalyst is the substance which promote the chemical action but never change by itself. By these principles, it makes harmless substances by purifying harmful things in the air when you transmit the light in Optic Catalyst.