If you're interested, research the Wave-Particle Duality. It might help you understand what is going on here. I performed this experiment during my undergrad and basically this says that photons, and even other particles (like electrons), behave both as paticles and waves. The wave nature of light is what produces the bands.
If you like reading/learning about modern physics, some other really cool topics that had me intrigued (still do) in my modern/quantum classes are Quantum Entanglement and the Uncertainty Principle. If you are mathematically inclined try reading/looking at Schrodinger's equation. All of these might help shed some light (pardon the pun) on quantum mechanics. All of this stuff really changed the way I view the world around me!