You could try speaking with your neighbor in a friendly manner and ask if you can prune your side of that tree. Our neighbor behind us had no light coming in her window because of one of are large cedar trees. She paid for a tree pruner to come in and we supervised to be sure the tree wasn't ruined. We were happy and she got her light. You could ask your neighbor to join you in pruning the tree. If your neighbor is giving you problems then go to City Hall and ask for their help and also get to know your property laws in your State.