Real-time modal decomposition of fiber laser beams using a spatial mode multiplexer

Area of Science:

• Optics and Photonics
• Laser Physics
• Fiber Optics

Background:

• Modal decomposition is crucial for understanding and controlling laser beam properties.
• Existing methods for modal decomposition can be slow and computationally intensive.
• High-speed analysis is required for dynamic laser systems and advanced applications.

Purpose of the Study:

• To introduce a novel, high-speed optical approach for modal decomposition of fiber laser beams.
• To demonstrate the capability of GHz-level modal analysis.
• To apply the method for analyzing Q-switched pulses in multimode fibers.

Main Methods:

• Utilized a spatial mode multiplexer for optical modal decomposition.
• Developed a system capable of processing modal content at speeds up to the GHz level.
• Applied the technique to analyze the modal content of Q-switched pulses in a multimode fiber with dynamic mode behavior.

Main Results:

• Successfully demonstrated a novel optical approach for modal decomposition.
• Achieved modal decomposition speeds up to the GHz level.
• Provided detailed modal analysis of Q-switched pulses exhibiting alternating intra-pulse mode content.

Conclusions:

• The demonstrated optical modal decomposition technique offers unprecedented speed for fiber laser analysis.
• This GHz-level capability opens new avenues for real-time monitoring and control of complex laser systems.
• The method is effective for analyzing dynamic modal phenomena in pulsed fiber lasers.