AeroStar Advance 150A HV (6~12S) Brushless ESC (Opto)

AeroStar Advance 150A HV (6~12S) Brushless ESC (Opto) says no BEC says OPTO Coupled I'm not familiar with that. So what does that mean (OPTO) Coupled but it looks like to me in the picture there is a BEC.