Main Page | See live article | Alphabetical index In telecommunication, the term overfill has the following meanings: 1. The condition that prevails when the numerical aperture of an optical source, such as a laser, light-emitting diode, or optical fiber, exceeds that of the driven element, e.g., optical fiber core. 2. The condition that prevails when the beam diameter of an optical source, such as a laser, light-emitting diode, or optical fiber, exceeds that of the driven element, e.g., optical fiber core. Note: In optical communications testing, overfill in both numerical aperture and mean diameter (core diameter or spot size) is usually required. Source: from Federal Standard 1037C This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.