Coherent addition of spatially incoherent light beams

Abstract

We report on efficient coherent addition of spatially incoherent multimode laser beam distributions. Such addition is demonstrated within a multi-channel laser resonator configuration, obtaining more than 90% combining efficiency while preserving the good beam quality. We explain the rather surprising physical phenomenon of coherently adding spatially incoherent light by self-phase-locking of each of the modal components within the multimode beams. Our approach could lead to significantly higher output powers concomitantly with good beam qualities than were hitherto possible in laser systems.

Coherent addition of orthogonally polarized fibre lasers with high combining efficiency

“…Due to high radiation intensities inside a fibre, optical breakdown and nonlinearities are limiting the power extractable from a single fibre laser. A convenient approach to coherent addition of fibre lasers is based on the use of a multi-arm resonator in an interferometer configuration [1][2][3][4][5][6][7][8][9][10]. The coherent combining takes place due to self-organization in laser generation that ensures amplification of resonator modes with the lowest losses.…”

“…Michelson and MachZehnder type resonators have been successfully used to reach nearly 100% combining efficiency of two fibre lasers. Coupling was obtained when two amplifying fibres shared a common output mirror located on one port of a standard 50/50 coupler which mixed both optical beams [1][2][3][4][5][6][7][8][9]. When beams of the two input ports of the beam splitter had the correctly fixed relative phase, they interfered constructively at the output port.…”

The effect of different power spectral densities of refractive index on the propagation of coherently combined beams

“…An alternative approach is to use arrays of relatively lower power lasers by combining the outputs of multiple laser sources to obtain a single output beam [1][2][3][4][5]. In recent years, the propagation of a coherently combined beam in Obukhov-Kolmogorov (OK) turbulence has been extensively studied.…”

Mutual injection locking and coherent beam combining of multiple Nd:YVO 4 lasers

“…It provides the benefit of creating a high average power beam from individual lasers. Different techniques, based on spectral combining [1], nonlinear optical conversion [2], coherent beam combining [3][4][5][6][7][8][9][10][11] have been explored and investigated. Among these techniques, coherent combining allows phase-locked multiple laser beams to form a combined beam with high power and good spatial coherence otherwise difficult to achieve for a single laser.…”

“…One is to use the split beams of a stable master laser to injection lock multiple slave lasers [3], which requires a separate stable master laser and active stabilization systems. Another is to combine beams supported by multiple gain elements in a single cavity, for example multiple gain filaments in the same gain medium created by multiple pumping beams for solid state lasers and semiconductor laser array [4][5][6][7][8][9][10][11]. This approach is suitable to create the individual high power lasers.…”