High-power phase locking of a fiber amplifier array

High-Power Fiber Lasers

“…Shay et al [42] experimentally demonstrated an original technique for coherent beam combining of laser beams. Using a so-called Locking of Optical Coherence by Single-detector Electronic-frequency Tagging (LOCSET), the authors achieved phase locking of an array of five 145-W fiber amplifiers.…”

“…In addition, the amplitude of each RF frequency component contains the optical phase error signal for each of the array elements. By electronically extracting the optical phase error for each array element and feeding it back to the corresponding phase modulator, the authors [42] were able to lock each array element to the same phase as the other element in the system. Unlike other approaches, this technique does not require a reference beam.…”

Bandwidth analysis and improvement of the beam phasing of fiber amplifiers using the stochastic parallel gradient descent algorithm

“…Several approaches like multi-core fiber lasers, intracavity coupling and master oscillator power amplifier (MOPA) configurations have been proposed and robust beam phasing of a small number of fiber lasers has been demonstrated [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Up to now, the highest-power demonstrations have involved active beam phasing with the MOPA configuration [7][8][9][10]. There are three kinds of active beam phasing method; heterodyne phase detecting [4][5][6][7][8], multi-dithering technique [9,10] and the stochastic optimization algorithm [11][12][13][14][15].…”

“…In coherent beam phasing, multiple lasers are packaged into an array in which all of the array elements operate at the same wavelength, and the relative phases of the elements are controlled. Several approaches like multi-core fiber lasers, intracavity coupling and master oscillator power amplifier (MOPA) configurations have been proposed and robust beam phasing of a small number of fiber lasers has been demonstrated [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Up to now, the highest-power demonstrations have involved active beam phasing with the MOPA configuration [7][8][9][10].…”

“…Up to now, the highest-power demonstrations have involved active beam phasing with the MOPA configuration [7][8][9][10]. There are three kinds of active beam phasing method; heterodyne phase detecting [4][5][6][7][8], multi-dithering technique [9,10] and the stochastic optimization algorithm [11][12][13][14][15]. Coherent beam phasing using the stochastic optimization algorithm is considered to be of great potential as it introduces less complexity while maintaining the capability for scaling to a large number of beamlets.…”