Can photons also work as a catalyst?
I do not feel that the word catalyst applies to photochemistry.

Photochemistry allows to access much higher energy states and thus reach reaction pathways that are otherwise not possible. Photons do not stabilize transition states (how would you rationalize the interaction?).

Catalysts on the other hand are focused on lowering barriers so that reactions proceed via lower energy transition states.

Because catalysts only affect the transition states, catalysts cannot affect the equilibrium position of a reaction. For example, if you had a catalyst that allowed easier conversion between (E)- and (Z)- double bonds, you could not use the catalyst to selectively provide the one that is less favorable.

On the other hand, with photochemistry, we do not establish an equilibrium because the higher energy state is not necessarily accessible via microscopic reversibility. And indeed, we can selectively use photochemistry to provide the less favorable species as is well know in the case of stilbenes.

EDIT:

Thanks to airhuff for pointing out that the requirement that a catalyst not be consumed also implies that we should not think about photons as catalysts. Hard to imagine a situation where you would absorb a photon and release one that is the same energy...