A fiber amplifier is an optical amplifier component that directly amplifies an optical signal by a fiber optic communication system. In a communication system using an optical fiber, there is no need to convert an optical signal into an electrical signal and directly amplify the optical signal.

An erbium-doped fiber amplifier (EDFA is an optical signal amplifier incorporating erbium ion Er3 + in the core of the signal.) It was the first optical amplifier developed by the University of Southampton in 1985. It is the greatest fiber optic communication. One of the inventions.

The erbium-doped fiber is a fiber in which a small amount of rare earth element erbium (Er) ions are doped into the quartz fiber, which is the core of the erbium-doped fiber amplifier. Since the late 1980s, research work on erbium-doped fiber amplifiers has continued to make major breakthroughs. WDM technology greatly increases the capacity of fiber-optic communication. It has become the most widely used optical amplifier component in fiber optic communications.

Term: erbium-doped fiber amplifier

Common alias: Erbium Doped Fiber Application Amplifier; Erbium Doped Fiber Amplifier

Abbreviation: EDFA

Origin: Er-Doped Fiber Amplifier

Related terms: Optical Amplifier

The quartz fiber is doped with rare earth elements (such as Nd, Er, Pr, Tm, etc.) to form a multi-level laser system, which directly amplifies the input signal light under the action of pump light. A suitable fiber laser is provided after providing appropriate feedback. The operating wavelength of the Nd-doped fiber amplifier is 1060 nm and 1330 nm. Due to the deviation from the optimal port of optical fiber communication and other reasons, its development and application are limited. The operating wavelengths of EDFA and PDFA are respectively in the lowest loss (1550 nm) and zero dispersion wavelength (1300 nm) window of fiber communication, and TDFA works in S band, which are very suitable for fiber communication system applications. In particular, EDFA has developed most rapidly and has been put into practical use.

Based on the development of erbium-doped fiber, many new fiber amplifiers have emerged. For example, a double-band fiber amplifier (DBFA) based on erbium-doped fiber is a broadband optical amplifier that can cover almost the entire wavelength division multiplexing. (WDM) bandwidth. A similar product is the Ultra Wideband Optical Amplifier (UWOA), which has an overlay bandwidth that amplifies up to 100 wavelength channels in a single fiber.

Principle of EDFA

The basic structure of EDFA is shown in Figure 1(a). It is mainly composed of active medium (bathed quartz fiber with a length of several tens of meters, core diameter 3-5 microns, doping concentration (25-1000) x10-6). , pump source (990 or 1480nm LD), optocoupler and optical isolator. The signal light and the pump light can propagate in the same direction (same direction pump), in the opposite direction (reverse pumping), or in both directions (bidirectional pumping) in the helium fiber. When the signal light and the pump light are simultaneously injected into the 铒 fiber, the erbium ion is excited to a high energy level under the action of the pump light (Fig. 1 (b), three-level system), and decays rapidly to the metastable level. When the incident signal light returns to the ground state, the photon corresponding to the signal light is emitted, and the signal is amplified. Figure 1 (c) shows its amplified spontaneous emission (ASE) spectrum with a large bandwidth (up to 20-40 nm) and two peaks corresponding to 1530 nm and 1550 nm, respectively.

The main advantages of EDFA are high gain, large bandwidth, high output power, high pumping efficiency, low insertion loss, and insensitivity to polarization.

For erbium-doped fiber amplifiers in CATV applications see: "1550nm Cable Signal Fiber Amplifier (EDFA)"