Amplified Spontaneous Emission (ASE) is a type of background noise that is common to all types of erbium-doped fiber amplifiers (EDFAs). It is generated when photons spontaneously emit from the erbium-doped material, which is found in the core of the EDFA’s optical fiber cable. The noise is produced as a result of the interaction between the photons and the erbium ions.
When the photons interact with the erbium ions, they excite the erbium ions which, in turn, release more photons and create a cascade of light emission. This cascade of photons is known as the Amplified Spontaneous Emission. ASE is an unavoidable form of noise which increases with the optical power, and is a major contributor to the EDFA’s noise figure. The higher the optical power, the higher the ASE level.
ASE can be reduced by using special optical filters, such as bandpass filters, which allow only specific wavelengths of light to pass through. This helps to reduce the amount of noise generated, as well as improve the signal-to-noise ratio (SNR). Additionally, careful selection of erbium-doped fiber amplifiers can also help to reduce the ASE level, as some EDFA models are designed to produce lower levels of noise.
For most applications, it is important to keep ASE levels to a minimum. The higher the ASE level, the lower the SNR, which can lead to data loss. By carefully selecting the right EDFA and using suitable optical filters, it is possible to reduce the ASE level and maintain a good SNR. This will ensure that the data transmitted through the optical fiber cable is not affected by the background noise, and can be accurately received at its destination.