Hello, I'm a business major who has recently stumbled upon the interesting phenomena of photonic crystals. After reading numerous papers and websites on the topic; however, there are many things that go over my head since I have very little knowledge in physics. I'm hoping that someone with more expertise can help me answer a couple of questions: 1. If you are trying to propagate light in one direction in a 2D crystal slab, do you still have to worry about scattering losses through the sides of the crystal, or does that only occur when you try to bend the light? 2. Are complete band gaps necessary for light traveling in one direction (could a 2D crystal band gap reflect all of the light in that frequency traveling through the crystal if it is all being propagated from the same side of the crystal)? Does this also depend on the angle of the incident light? 2. When you use waveguides in a 2D crystal is all the light energy (besides whatever frequency is in the band gap) propagated through the waveguide or are there some substantial losses? (I'm thinking about applications to band-width narrowing here). 3. Have they developed photonic crystal band gaps for every frequency (from UV light to microwaves for example)? Are some of these gaps only possible in 3D crystals? Wow, this is a lot of questions, I think I'll stop there. Any help would be appreciated, just pick a question to answer or leave a helpful link, please. Thank you!