Quasi mode-locking of coherent feedback random fiber laser

Area of Science:

• Laser Physics
• Photonics
• Materials Science

Background:

• Mode-locking, crucial for short pulse generation and laser stabilization, was traditionally observed only in ordered lasers.
• Recent findings indicate mode-locking can occur in disordered random lasers, expanding the understanding of laser dynamics.
• Coherent feedback random fiber lasers offer a unique platform for exploring lasing phenomena in disordered systems.

Purpose of the Study:

• To realize and investigate quasi mode-locking in a coherent feedback random fiber laser with a partially disordered cavity.
• To demonstrate the generation of multiple regular light pulse groups with distinct repetition frequencies.
• To explore the underlying mechanism of collective resonances in this random laser system.

Main Methods:

• Fabrication of a linear cavity comprising a point reflector, a random distributed fiber Bragg grating array, and a graphene saturable absorber.
• Experimental investigation of the laser output under quasi mode-locking conditions.
• Analysis of pulse characteristics and repetition frequencies using spectral and temporal measurements.

Main Results:

• Successful realization of quasi mode-locking in the designed coherent feedback random fiber laser.
• Observation of multi-groups of regular light pulses/sub-pulses with different repetition frequencies.
• Attribution of pulse generation to the collective resonances phenomenon within the disordered laser cavity.

Conclusions:

• The study demonstrates a novel approach to achieving quasi mode-locking in disordered random fiber lasers.
• This work provides a valuable platform for studying mode-locking dynamics and pulse regulation in coherent feedback disordered structures.
• The findings pave the way for developing novel multi-frequency pulse fiber lasers with tunable frequency ranges.