High power fiber amplifier is a device that amplifies optical signal power based on fiber optic media, with output power typically reaching watts or above. It is widely used in fields such as laser processing, optical communication, and LiDAR.
High power fiber amplifiers are mainly based on seed source main oscillator amplification technology (MOPA), using high beam quality, low-power solid-state or fiber lasers as seed light sources and double clad fibers as amplifiers. By coupling the signal light into the fiber core and the pump light into the inner cladding of the fiber, the pump light is absorbed by doped ions during transmission in the fiber, forming a particle number inversion to achieve gain. When signal light passes through the fiber core, particles in the excited state generate stimulated radiation under the action of external signal light. This radiation is amplified by superimposing it on the external signal light, resulting in high-power and high-quality amplified laser output.
working principle
Using rare earth doped optical fibers (such as erbium-doped and ytterbium doped fibers) as gain media, energy is injected into the fiber through a pump light source (usually a semiconductor laser) to transition the doped ions from the ground state to the excited state.
Excited state ions are excited by incident signal light to produce stimulated radiation, releasing photons of the same frequency and phase as the signal light, achieving signal light power amplification.
Equipped with optical isolators, optocouplers and other components to avoid reflected light interference and ensure stable amplification process.
Core structure
Seed source: providing high beam quality and low power initial optical signals, which is the starting point of the amplification process.
Pump source: provides energy for the amplification process, usually using high-power laser diodes.
Gain medium fiber: Adopting a double clad fiber structure, the core of the fiber is doped with rare earth ions (such as erbium, ytterbium, etc.), which is the core area of signal amplification.
Optical isolator: prevents reverse spontaneous emission (ASE) light generated in the amplification system from entering the seed source and affecting its normal operation.
Coupling system: coupling signal light and pump light into the fiber core and inner cladding respectively to ensure effective optical transmission and amplification.