A method for forming a flat panel display includes disposing a light guide plate below a display panel, disposing at least one optical film between the display panel and the light guide plate, and disposing at least one illuminating device package in proximity to the light guide plate. The method for forming the illuminating device package includes forming a light emitting diode device over a substrate and forming a lens encapsulating the light emitting diode device. The lens includes two reflective surfaces disposed substantially symmetrically at either side of a central axis. The reflective surfaces is configured to reflect portions of light beams to at least one of the diffractive surfaces. The lens also includes a plurality of diffractive surfaces separating the reflective surfaces. The diffractive surfaces are configured to diffract the reflected light beams into a convergent angle. Each of the diffractive surfaces having a tilt angle respective to the central axis.