I hope this message finds you well, present circumstances excluded. Unfortunately, you are reliant on your local law enforcement and DA to file charges. It appears that at the moment they are uninterested. I have seen situations like this before and there are ways to get your point across, but you have to be persistent. Remember that the squeaky wheel gets the grease.
As you have stated, keeping a journal and logging the specifics of what is going on is very much the key to a strong foundation for harrassment. You could go a step further and keep a video journal as well. If he is shining a laser into your home, videotape it while it is taking place. If he is dumping litter into your yard, take pictures or video tape the matter.
I would take a multi-level approach to getting the law enforcement involved. You could write a letter to your mayor, county sheriff (not deputy), district attorney and perhaps board of supervisors that includes a copy of your journal documentation of the events and respectfully XXXXX XXXXX something be done to alleviate this issue. Ask that they respond to you in writing within a specified amount of time (14 days is reasonable). You should also copy the state attorney general on this letter. I doubt the AG will respond, but the fact that he is cc'ed on the matter may make the others take notice. If you have not heard from the people, excluding the AG's office, within 14 days, you should call them until you get them on the phone. If nothing else, they will likely take action just to appease you.
If you are able to get video or photographic evidence of the actions of your neighbor, you should, as soon as is possible, actually go to the sheriff office and ask to file charges based on the evidence you have in hand.
I do not necessarily recommend this last measure, but I have seen it work in the past. If you have a local TV station, you may want to contact them and explain what is going on and how you have not had any help from local law enforcement or the DA's office. Sometimes the local media will run a series on the lack of attentiveness of the local police, sheriff office, DA, etc. The spotlight often times motivates. Again, I would only do this as a last resort.
The bottomline is this, you need to remember that you have a right to privacy. You should, in addition to the measures recommended above, call the law enforcement everytime something as you have described takes place. They will notice a pattern and will eventually investigate what is going on.
One last thing, you can go to the local sheriff's office and ask to fill out an affidavit, or sworn statement, as to what has been taking place. This sworn statement will go a long way towards forcing the sheriff's office to investigate the merits of your claim.
I hope this helps and best wishes.