Small-form-factor fiber optic interface devices with an internal lens are disclosed. The fiber optic interface devices have a ferrule with a bore that supports an optical waveguide. The lens is on or adjacent the ferrule front end and is aligned with the bore. A first planar surface is provided on or adjacent the lens. The first planar surface interfaces with a second planar surface of a second fiber optic interface device to form a fiber optic interface assembly having a liquid-displacing interface when the first and second fiber optic interface devices are engaged.