Thaks Jai_Nepal! I appreciate your help. In fact I did  search on google and read couple of times the page you posted here before asking the question on this sajha. My confusion was I couldnt find anywhere that says they need experience letter for filing H1-B. So, My question was how important is the experience letter and how can I ask to my former and current employer about my experience letter without letting my current manager know that I am quitting the job. Thanks for your help.