Affiliation:
1. Xi’an Institute of Optics and Precision Mechanics
2. Institute of Semiconductors
3. Engineering Technology Research Center of All-Solid-State Lasers Advanced Manufacturing
4. University of Chinese Academy of Sciences
Abstract
This paper provides a method to effectively suppress the severe ASE self-saturation when achieving high repetition frequency tunability with high output power and narrow pulse width in active Q-switched all-fiber lasers. By studying the regularity of the system's multi-stable state, we first ensured that the laser system operated in a steady state. Then output avoids uneven distribution of pulse energy or missing pulses due to period bifurcation state or chaos state. By adding multiple gain sub-rings within the cavity, the sub-ring structure itself indirectly mitigates the ASE self-saturation while smoothing the pulse. The method will avoid the severe power loss caused by traditional smoothing methods by adjusting the AOM rising edge time. It will also avoid lowering the ASE lasing threshold at high repetition frequency. Meanwhile, the intra-cavity backward ASE can be effectively absorbed by inserting the gain fiber in the sub-rings to directly mitigate the ASE self-saturation. The system's continuously adjustable repetition frequency can be as high as over 300 kHz. It ensures that output power above the watt level and a < 0.2 nm narrow bandwidth can be maintained while tuning the repetition frequency. The narrowest smoothing pulse width of 28 ns has been reached.
Funder
CAS Project for Young Scientists in Basic Research
National Natural Science Foundation of China
Scientific Instrument Developing Project of the Chinese Academy of Sciences
National Key Research and Development Program of China
Key Program of the Chinese Academy of Sciences
Subject
Atomic and Molecular Physics, and Optics