All-fiber coherent beam combining of fiber lasers

Abstract

One half of a 2x2 fused taper single-mode fiber coupler is used for the all-fiber spatial and spectral beam combining of two fiber lasers.

Coherent combining of the output of two semiconductor lasers using optical phase-lock loops

“…1,2 Various technologies have been explored to achieve the goal by using semiconductor (SC) lasers and fiber lasers. 1,[3][4][5][6][7][8] In this Letter we report what we believe to be the first coherent power addition of two commercial grade SC lasers by using current-injection optical phase-lock loops [9][10][11][12][13] (OPLLs). Compared with the previous coherent power-combining techniques, including the optical injection OPLLs, the current-injection OPLLs technique can provide individual electronic control of the frequency and phase of each laser in an array without external phase modulators and thus can lead to a big coherent emitting aperture that can be controlled, focused, distortion corrected, scanned in space, and pulsed by using pure electronic control.…”

Coherence between two coupled lasers from a dynamics perspective

“…An alternative approach has recently been developed to enforce coherent beam combination in arrays [7,8,9,10,11,12,13,14]. In addition to a passive coupling arrangement among the elemental lasers, losses incurred at the individual output facets are purposely imbalanced.…”

“…Experimental investigations have reported emission of inphase coherent light solely from the output reflector having the lowest losses. This form of single-facet emission has been studied primarily in arrays of solid-state and fiber lasers using interferometric coupling devices such as beam splitters [15,16], fold mirrors [14], or directional couplers [8,9,10,11,13,17]. In most realizations only one coupler output is fitted with a reflector to provide a global feedback for the entire array.…”

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.…”