I am so happy to hear you enjoyed the cruise and the excellent service you received. We receive requests such as yours often.
I asked Carnival's public relations manager about this a few months ago and he said Carnival does not release contact information for their employees. This is to protect their privacy. I'm sure you can appreciate that.
However, I was also told that if passengers wished to send along their appreciation to specific crew members they should simply send them to Carnival's main office. I was assured that they would forward them to the proper persons on the ship. Here is the link