Spatiotemporal self-mode-locked operation in a compact partial multimode Er-doped fiber laser

Area of Science:

• Optics and Photonics
• Laser Physics
• Fiber Optics

Background:

• Mode-locked fiber lasers are crucial for various applications, but achieving spatiotemporal mode-locking in compact systems remains challenging.
• Multimode fiber lasers offer potential for novel optical phenomena due to complex light-matter interactions.

Purpose of the Study:

• To demonstrate spatiotemporal self-mode-locked operation in a compact partial multimode fiber laser system.
• To investigate the generation and characteristics of multimode solitons and soliton molecules.
• To explore the factors influencing spatiotemporal soliton evolution and stability.

Main Methods:

• Utilized a compact partial multimode fiber laser configuration operating at 1.55 µm.
• Employed multimode interference (linear and nonlinear) for spatial filtering and saturable absorption.
• Investigated the spatiotemporal dynamics of generated solitons and soliton molecules.

Main Results:

• Achieved spatiotemporal self-mode-locked operation with a low pump threshold of 32 mW.
• Generated stable multimode conventional solitons with varying spectral bandwidths.
• Observed multimode soliton molecule complexes with distinct bound-state patterns.
• Identified dependencies of soliton evolution on operating state, frequency components, and soliton interactions.
• Observed an unstable spatiotemporal mode-locked (STML) state under specific conditions.

Conclusions:

• The hybrid single mode-multimode fiber configuration effectively supports spatiotemporal self-mode-locking.
• The system provides a versatile platform for studying complex nonlinear optical phenomena in multimode solitons.
• Further research can explore controlling the observed unstable STML state for novel applications.