We are interested on studying the mechanism which gives rise to the spatial distribution of the electromagnetic field in the plane orthogonal to the direction of propagation of the light. In large aperture lasers pattern formation becomes almost boundary-free, and it is dominated by bulk parameters and nonlinearities of the active medium. In particular, we have reported the first experimental observation of the fast dynamics of 2D transverse patterns. We have used a TEA pulsed CO2  broad area laser with Fresnel number ~ 10. The transverse pattern is formed by laser emission bright peaks (optical filaments) which are aperiodically flashing in time with different growing rates. The lifetime of these optical filaments is around 2 ns. Pairs of consecutive instantaneous patterns separated by different time delays The transmitted pattern (left) is recorded a time td before than the reflected pattern (right). For small time delays, there are many common filaments (high spatio-temporal correlation) When increasing time between consecutive patterns they become more dissimilar without any common filaments (loss of spatio-temporal correlation)

Oscar G. Calderón, Departamento Optica, UCM
Eduardo Cabrera, Departamento Optica, UCM
Fernando Encinas-Sanz, Departamento Optica, UCM
Jose Manuel Guerra, Departamento Optica, UCM


Publications 

• Evolution of the correlation between orthogonal polarization patterns in broad area lasers, Phys. Rev. Lett. 97 (2006) 233902
• Development of spatial turbulence from boundary-controlled patterns in class-B lasers, Phys. Rev. A 73 (2006) 053820(1-6)
• Dynamic transition from modelike patterns to turbulentlike patterns in a broad-area Nd:YAG, Optics Letters 31 (2006) 1067-1069
  
• Effects of injected atomic coherence in broad area lasers, Phys. Rev. A 72  (2005) 033811 (1-7)
  
• Time-resolved dynamics of two-dimensional patterns in broad area lasers, Phys. Rev. Lett. 93  (2004) 213904 (1-4) 

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