Laminar-Turbulent Transition in Raman Fiber Lasers: A First Passage   Statistics Based Analysis
  Loss of coherence with increasing excitation amplitudes and spatial size modulation is a fundamental problem in designing Raman fiber lasers. While it is known that ramping up laser pump power increases the amplitude of stochastic excitations, such higher energy inputs can also lead to a transition from a linearly stable coherent laminar regime to a non-desirable disordered turbulent state. This report presents a new statistical methodology, based on first passage statistics, that classifies lasing regimes in Raman fiber lasers, thereby leading to a fast and highly accurate identification of a strong instability leading to a laminar-turbulent phase transition through a self-consistently defined order parameter. The results have been consistent across a wide range of pump power values, heralding a breakthrough in the non-invasive analysis of fiber laser dynamics. 
Amit K Chattopadhyay, Diar Nasiev, Srikanth Sugavanam, Nikita Tarasov   and Dmitry Churkin
physics.optics cond-mat.stat-mech physics.data-an