When the transmission distance is too long (greater than 100 km), the optical signal will have a large loss. In the past, people usually used optical repeaters to amplify the optical signal. This kind of equipment has certain limitations in practical applications, and has gradually been used. The fiber amplifier is replaced by the working principle of the fiber amplifier. It can directly amplify the optical signal without going through the process of optical-electrical-optical conversion. Let's learn about it together.
How does a fiber amplifier work?
When the transmission distance is too long (greater than 100 km), the optical signal will have a large loss. In the past, people usually used optical repeaters to amplify the optical signal. This kind of equipment has certain limitations in practical applications, and has gradually been used. It can directly amplify the optical signal without going through the process of optical-electrical-optical conversion.
fiber optic cabling
What kinds of fiber amplifiers are there?
1. Erbium-Doped Fiber Amplifier (EDFA)
Erbium-doped fiber amplifier (EDFA) is mainly composed of erbium-doped fiber, pump light source, optical coupler, optical isolator and optical filter. Therefore, Erbium-Doped Fiber Amplifiers (EDFAs) work best in the wavelength range of 1530 nm to 1565 nm.
advantage:
Highest pump power utilization (greater than 50%)
Direct and simultaneous amplification of optical signals in the 1550 nm band
Gain over 50 dB
Low noise in long distance transmission
shortcoming
Erbium-Doped Fiber Amplifier (EDFA) is bulky
This device does not work in harmony with other semiconductor devices
2. Raman amplifier
The Raman amplifier is the only device that can amplify the optical signal in the 1292 nm~1660 nm band. Its working principle is based on the stimulated Raman scattering effect in the silica fiber, as shown in the figure below, when the pump light pulls When the weak light signal within the Mann gain bandwidth and the strong pump light wave are transmitted in the fiber at the same time, the weak light signal will be amplified by the Raman scattering effect.
advantage:
Wide range of applicable frequency bands
Can be used in installed single-mode fiber optic cabling applications
Complements Erbium-Doped Fiber Amplifiers (EDFAs)
Low power consumption and low crosstalk
shortcoming:
High pump power
The gain control system is complex
loud noise
3. Semiconductor Optical Amplifier (SOA)
Semiconductor fiber amplifier (SOA) uses semiconductor material as the gain medium, and its optical signal input and output have anti-reflection coatings to prevent the reflection of the end face of the amplifier and eliminate the effect of the resonator.
advantage:
small volume
low output power
Small gain bandwidth, but can be used in many different bands
Cheaper than Erbium-Doped Fiber Amplifiers (EDFAs) and can be used with semiconductor devices
Four nonlinear operations of cross-gain modulation, cross-phase modulation, wavelength conversion and four-wave mixing can be realized
shortcoming:
Not as high performance as Erbium-Doped Fiber Amplifiers (EDFAs)
High noise, low gain
