Research Status of Amplified Spontaneous Emission Sources based on Doped Materials

Abstract

Amplified spontaneous emission (ASE) was once considered a harmful parasitic effect. This is because ASE will reduce the number of the inverted population in the gain medium, thereby reducing the efficiency of lasers. However, the output characteristics of ASE make it applicable to many studies. Therefore, the experimental settings and beam output characteristics of different doped laser ASE sources are summarized in this review. The summarization begins with the characteristics of ASE, such as threshold condition. Then, two doped fiber lasers are introduced. Based on erbium-doped fiber, an ASE source with high stability is made by measuring the best parameters and selecting a suitable structure. The ytterbium-doped fiber can benefit Q-switch pulses and high-order Stokes generation by suppressing the self-saturation of ASE and offering gain for ASE, respectively. Besides, three different ASE sources based on Nd-doped laser crystals are presented. They are spatially selective ASE sources that achieve high-intensity, narrow-bandwidth output pulses and Q-switching in a cavityless laser. Additionally, the performance of the ASE source can also be improved by doping with gold nanoparticles, Gd3+, and other particles.