Build-up dynamics in bidirectional soliton fiber lasers

Abstract

Bidirectional ultrafast fiber lasers present an attractive solution, enabling the generation of two mutually coherent ultrashort pulse trains in a simple and turnkey system. Still, the lack of a comprehensive numerical model describing steady-state bidirectional generation, and even less ultrafast soliton breakdowns and collisions, is obstructing the achievement of the performance compared with unidirectional lasers. In this paper, we have experimentally investigated real-time build-up dynamics of counter-propagating solitons in an ultrafast ring Er-doped fiber laser via the dispersive Fourier transform methodology. We parade that counter-propagating pulses experience independent build-up dynamics from modulation instability, undergoing breathing dynamics and diverging subordinate pulse structure formation and annihilation to a stable bidirectional pulse train. Yet, the interaction of pulses in the cavity presents the key underlying phenomenon driving formation evolution distinct from unidirectional pulse build-up. Our findings will provide physical foundations for bidirectional ultrafast fiber laser design to carry forward their application.

Pulse-onset dynamics in a bidirectional mode-locked fibre laser via instabilities

“…Throughout the entire dynamics and stable propagation, except for central wavelength shift, counterpropagating pulses have had identical repetition rates. In contrast, in our previous work 32 , both pulses had a slight mismatch in repetition rates. Although recorded several dozens of switch-on dynamics demonstrate similar features mentioned above, there has been no preferred sequence of events or single pathway to stable mode-locking generation.…”

“…When pulses undergo through simpler build-up dynamics shown in ref. 32 no unsynchronised resonant DWs were observed. The results presented here indicate that unsynchronised resonant DWs are dependent on the initial conditions of pulse formation.…”

“…Although recorded several dozens of switch-on dynamics demonstrate similar features mentioned above, there has been no preferred sequence of events or single pathway to stable mode-locking generation. The current work presents an extension of our previous efforts of discovering build-up phenomena in bidirectional lasers, where the formation of pulses from continuous-wave radiation by adjustment of polarisation controllers was discussed 32 . The existence of myriad phenomena and events shows the potential of bidirectional ultrafast laser platform to serve as an efficient test-bed for the investigation of complex dynamics of nonlinear systems in general.…”

Dynamics of carbon nanotube-based mode-locking fiber lasers

“…Some critical phenomena are also observed, including transient complex spectrum broadening and frequency-shift interaction of SPs and picosecond pulses. More recently, Kudelin et al experimentally demonstrated that bidirectional soliton fiber laser experience independent buildup dynamics from modulation instability, undergoing breathing dynamics and diverging sub-ordinate pulse structures formation and annihilation [234]. In the same way, the similar behaviors dissipative soliton in a net-normal-dispersion bidirectional ultrafast fiber laser were also observed by Luo et al [235].…”

Real-time pulse dynamics in bidirectional mode-locked fibre lasers

“…In the current presentation, real-time build-up dynamics of counter-propagating solitons in ultrafast ring Er-doped fibre laser, recorded via the dispersive Fourier transform methodology, will be discussed [9]. Even though the counter-propagating pulses experience independent build-up dynamics from modulation instability, undergoing breathing dynamics, diverging sub-ordinate pulse structures formation and annihilation, and Q-swtuch instabilities, etc.…”