Turbulence in mode-locked lasers

We show that the well-known instability in actively mode-locked lasers with detuning between the resonator round-trip time and the modulator period ex hibits a transition to turbulence analogous to fluid flow. We derive a univ ersal normalized detuning of the laser that plays the same role as Reynolds number in fluid flow. This is the first time that the recently proposed th eory for the onset of turbulence in hydrodynamics is verified in a system o utside of hydrodynamics. [S0031-9007(99)09268-6].