Doped fibres are often used as optical amplifiers within optical networks. Erbium is the most common dopant - it follows that Erbium Doped Fibre Amplifiers (EDFAs) are the most common optical amplifiers of this type. EDFAs are pumped with a diode laser with a central wavelength of 980 nm that is multiplexed with the signal-carrying fibre. The pump radiation excites the dopant ions along the fibre amplifier.
The excited erbium ions then undergo a rapid, non-radiative relaxation to a lower energy band, after which they experience a slow, radiative relaxation to their ground state. The relative decay times of these states are critical to the achievement of population inversion – a prerequisite for high stimulated to spontaneous emission ratio, which, in more practical considerations, manifests itself as a high signal-to-noise ratio and greater amplification efficiency.
The solution comprises of a distributed feedback (DFB) laser source, a 980 nm pump module, a multiplexer, an EDFA and spectral analyser. The DFB laser source and the pump module’s outputs were combined using the multiplexer and then transmitted through the EDFA.