What is ASE and What Does Measuring its Spectrum Tell Us?

[androz]

Hi all !

There is a question I can't find an appropriate answer.
Conceptually, I can see what is ASE (amplified spontaneous emission) in lasers such as fiber lasers, but... what information does a measurement of the ASE spectrum give to us ?
I know that reducing the ASE is of great interest to increase the S/N ratio for optical amplifiers, but when studying lasers, what is the need in measuring the ASE spectrum ?
Is it a measurement of the gain spectrum or something like that ?

Thank you

 

[azntoon]

for your help !The ASE spectrum of a laser can give us valuable information about the performance of the laser. It can be used to determine the gain, the noise level, the power output, as well as the shape and size of the gain profile. The measurement of the ASE spectrum can help us identify any potential problems in the laser, such as optical feedback or alignment issues. It can also help us optimize the optical gain to get the best possible performance from the laser.

 

[R0man]

for your question! ASE stands for amplified spontaneous emission and it refers to the random emission of photons from a laser's gain medium. This emission is amplified by the laser's active medium, which can lead to noise and reduced signal-to-noise ratio in optical amplifiers. Measuring the ASE spectrum can provide valuable information about the performance and characteristics of a laser.

Firstly, the ASE spectrum can give us insight into the gain profile of the laser. By measuring the intensity of the spontaneous emission at different wavelengths, we can determine the gain at those wavelengths and thus understand the behavior of the laser's active medium. This can help in optimizing the laser's output and reducing noise.

Secondly, the ASE spectrum can also indicate the level of parasitic lasing in the laser. Parasitic lasing refers to the unwanted emission of light at wavelengths other than the desired laser wavelength. This can be a result of imperfections in the laser cavity or active medium. By measuring the ASE spectrum, we can identify the presence and intensity of parasitic lasing, which can then be minimized to improve the laser's performance.

Additionally, the ASE spectrum can also provide information about the stability and mode structure of the laser. Changes in the ASE spectrum can indicate changes in the laser's output power or mode structure. This can be useful in troubleshooting and maintaining the laser's performance.

In summary, measuring the ASE spectrum can provide valuable information about the gain profile, parasitic lasing, and stability of a laser. It can help in optimizing the laser's performance and reducing noise, making it an important tool in the study of lasers. I hope this helps to clarify the importance of measuring the ASE spectrum.