Source: Phys.org

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Soliton Mode Locking in Fiber and Bulk Lasers

Soliton Mode Locking of Fiber Lasers

Soliton mode locking is a technique used to generate femtosecond pulses in lasers, particularly in fiber lasers. It relies on the balance between chromatic dispersion and nonlinearity to maintain pulse shape and spectrum. Anomalous chromatic dispersion fibers are typically used for soliton mode locking in the 1-μm and 1.5-μm regimes. A saturable absorber is employed for initiating and stabilizing mode locking, while pulse shaping is mainly influenced by dispersive and nonlinear effects. The resulting pulses exhibit a sech² temporal profile with minimal chirp, indicating high pulse quality.

Quasi-Soliton Mode Locking of Bulk Lasers

In solid-state bulk lasers, quasi-soliton mode locking is achieved by introducing anomalous chromatic dispersion through elements like prism pairs or dispersive mirrors. This technique allows for the generation of quasi-soliton pulses by balancing dispersion and Kerr nonlinearity. The use of a saturable absorber is still necessary for mode locking initiation and stability. The performance of soliton mode-locked bulk lasers is optimal for pulse durations below 1 ps, as longer pulses require excessive anomalous dispersion and nonlinearity.

Optimizing Soliton Mode Locking

To optimize soliton mode locking, numerical simulations can be conducted to explore factors such as the impact of saturable absorber strength and nonlinear phase shifts on stability limits. By adjusting these parameters, the performance of soliton mode-locked lasers can be enhanced in terms of pulse energy and duration. Additionally, more sophisticated mode locking techniques have been developed for fiber lasers to improve performance and pulse shaping processes.

Conclusion

Soliton mode locking is a valuable technique for generating ultrashort pulses in both fiber and bulk lasers. By understanding the principles of soliton mode locking and optimizing key parameters, researchers and engineers can achieve high-performance laser systems with excellent pulse quality and stability.

Source: MDPI
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