A light guide plate having a top surface through which light is emitted, a bottom surface opposite to the top surface and a side surface between the top and bottom surfaces, a bottom reflector on the bottom surface for reflecting light at the bottom surface back into the light guide plate, light emitting diodes at the side surface and a side reflector on the side surface for reflecting light at the side surface back into the light guide plate, wherein the side reflector on the side surface has an opening corresponding to at least one of the light emitting diodes