For the measurement of an optical bandwidth, one often uses an optical spectrum analyzer. For example, it can be the reflection bandwidth of a mirror, the optical transmission bandwidth of an optical fiber, the gain bandwidth of an optical amplifier, or the. This Applications Engineering Note (AE Note) discusses bandwidth characterization for multimode optical fiber (MMF), and bandwidth's impact on overall system performance. Optical bandwidth is defined as the frequency at which half. Bandwidth describes the range of frequencies that can be transmitted through a channel, and consequently, the rate at which data can be transmitted through it. While copper cabling still offers cost and reliability advantages for short-distance.