BPM study of pump modulation effects on mode instability

Benjamin G. Ward

doi:10.1117/12.2577755

5 March 2021 BPM study of pump modulation effects on mode instability

Benjamin G. Ward

Proceedings Volume 11665, Fiber Lasers XVIII: Technology and Systems; 1166510 (2021) https://doi.org/10.1117/12.2577755
Event: SPIE LASE, 2021, Online Only

Abstract

Results of steady periodic finite element beam propagation (SP-FE-BPM) simulations of transverse mode instability (TMI) in representative coiled step index and large pitch photonic crystal fiber amplifiers with pump noise and modulation are presented and discussed. Modulating the pump power of fiber amplifiers near the TMI threshold complicates the conceptual picture due to the introduction of the additional dynamical time scale of the pump modulation. The time dependent mode field throughout the length of the amplifier calculated with the SP-FE-BPM was used to synthesize spatially and temporally resolved imaging measurements including spatial distribution of the amplitude and phase of different frequency components as a means to characterize the effects of pump modulation on TMI dynamics. Pump modulation was found to affect the threshold and dynamics of TMI in two amplifier configurations and a range of modulation cases. The step index fiber (SIF) amplifier was found on average to be approximately 20% more susceptible to pump noise than the large pitch fiber (LPF) amplifier. Furthermore a TMI dynamic not associated with stimulated thermal Rayleigh scattering that has been experimentally observed was observed in both SIF and LPF SP-FE-BPM simulations.

Conference Presentation

Citation Download Citation

Benjamin G. Ward "BPM study of pump modulation effects on mode instability", Proc. SPIE 11665, Fiber Lasers XVIII: Technology and Systems, 1166510 (5 March 2021); https://doi.org/10.1117/12.2577755

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