The main difference between ASE (Amplified Spontaneous Emission) and stimulated emission is the source of the emitted photons. In ASE, the photons are emitted spontaneously from the excited atoms or molecules, while in stimulated emission, the photons are stimulated and emitted by an external source.
In ASE, the emitted photons can compete with the desired stimulated emission, leading to a decrease in laser output power and efficiency. In contrast, stimulated emission increases the laser output power and efficiency by providing a source of coherent photons that can stimulate further emission.
Yes, ASE and stimulated emission can occur simultaneously in a laser system. However, the amount of ASE emission can be reduced by optimizing the laser design and controlling the gain medium's properties.
Stimulated emission is more desirable for laser applications because it provides a coherent and directional output beam, which is essential for most laser applications. ASE can lead to a decrease in laser performance and can cause unwanted noise in the laser output.
The effects of ASE can be minimized by optimizing the laser design, such as using a longer gain medium or reducing the gain medium's doping concentration. Additionally, using an external source to stimulate emission rather than relying solely on spontaneous emission can also help reduce the effects of ASE.