What is the characteristic of Raman optical amplifiers?

Raman optical amplifier is an important part of dense wavelength division multiplexing communication system. In many nonlinear optical media, the scattering of pump light with a shorter wavelength causes a small part of the incident power to be transferred to another beam whose frequency is shifted down. The amount of frequency shift down is determined by the vibration mode of the medium. This process is called the pulling Mann effect. If a weak signal and a strong pump light wave are simultaneously transmitted in the fiber, and the weak signal wavelength is placed within the Raman gain bandwidth of the pump light, the weak signal light can be amplified. This mechanism is based on stimulated Raman scattering The optical amplifier is called Raman optical amplifier.

Here is the content list:
Classification of Raman optical amplifiers.

Features of Raman optical amplifier.

Regarding the current status of optical amplifiers and Raman optical amplifiers.

Classification of Raman optical amplifiers
Raman optical amplifiers are mainly divided into two categories: discrete Raman optical amplifiers and distributed Raman optical amplifiers.

(1) Discrete Raman optical amplifiers, discrete Raman optical amplifiers use special fibers with higher Raman gain coefficients (such as highly doped germanium fibers, etc.). The length of this fiber is generally a few kilometers. Pump power requirements Very high. Generally, it is several W. Discrete Raman optical amplifiers can produce high gains of more than 40 dB. They are used to lumped up signal light like EDFA, so they are mainly used to achieve bands that EDFA cannot amplify.

(2) Distributed Raman optical amplifier. Distributed Raman optical amplifier can greatly improve the performance of the optical transmission system. From the technical principle, only Raman amplification technology can realize the distributed amplification in the optical transmission process. Therefore, the application prospects of distributed Raman optical amplifiers in the system are becoming increasingly important.

Features of Raman optical amplifier
advantage
Compared with other different types of optical amplifiers, Raman optical amplifiers have many advantages:

(1) It is very different from EDFA. The Raman optical amplifier does not need a special gain medium. As long as the ordinary transmission fiber can realize the optical signal amplification, it can realize the distributed amplification and direct the optical fiber amplification system. Relevant improvements such as capacity expansion and upgrading, and rational use of the low-loss window of optical fiber.

(2) The wavelength of the gain light of the Raman optical amplifier depends on the wavelength of the pump light. In theory, as long as the wavelength of the pump light is selected, any optical signal band can be amplified, and then the full range of Raman amplification can be realized.

(3) The Raman optical amplifier has a relatively wide frequency band. If a multi-wavelength pumped fiber Raman amplifier is used, a gain spectrum greater than 100 nm can be obtained.

(4) Low noise figure. The hybrid amplifier of EDFA and Raman optical amplifier can greatly improve the performance of the transmission system.

(5) The gain spectrum of the Raman optical amplifier has a superposition effect. The multi-pump method can obtain a wider Raman gain spectrum, and the Raman gain spectrum of a single wavelength will compensate each other, to achieve the effect of gain flatness. , To ensure the stability of the signal transmission.

(6) The saturation power is very high. When the amplified signal power begins to approach the pump power, the decrease in optical gain is only 3 dB.

Many of the above advantages also determine that Raman optical amplifiers can be widely used in WDM fiber communication systems.

Disadvantage
(1) Insufficient gain bandwidth;
(2) Low output gain;
(3) The output gain is not flat.

Regarding the current status of optical amplifiers and Raman optical amplifiers
Fiber amplifiers can be divided into two categories according to the different gain media: one type uses active media, such as semiconductor materials and rare-earth-doped fibers (Nd, Sm, Ho, Er, Pr, Tm, Yb, etc.), and uses stimulated emission mechanisms Realize the direct amplification of light, such as semiconductor laser amplifiers and doped fiber amplifiers; the other is based on the nonlinear effect of optical fibers to achieve optical amplification, typically Raman optical amplifiers and Brillouin fiber amplifiers. In recent years, the research and development of optical fiber amplifiers have been continuously progressing. Various types of optical amplifiers, such as erbium-doped fiber amplifiers, gain-shifted erbium-doped fiber amplifiers, thulium-doped fiber amplifiers, gain-shifted thulium-doped fiber amplifiers, and Raman optical amplifiers It is technically mature and covers the wavelength range of 1365~1 650 nm, making it possible to implement dense wavelength division multiplexing.

At last
Currently, erbium-doped fiber amplifiers and Raman optical amplifiers have been widely used commercially. Our company is good at producing Raman optical amplifiers. If you need them, please visit our company’s official website to contact us.


Post time: Dec-06-2021