Theory of spectral beam combining of fiber lasers

• Published in: IEEE journal of quantum electronics Vol. 38; no. 5; pp. 432 - 445
• Main Author: Bochove, E.J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2002; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Arrays; Bandwidth; Beams (radiation); Criteria; Diffraction; Efficiency, stability, gain, and other operational parameters; Error detection; Exact sciences and technology; Fiber lasers; Fundamental areas of phenomenology (including applications); Laser beams; Laser modes; Laser optical systems: design and operation; Laser theory; Lasers; Lenses; Optical arrays; Optical communication systems, multiplexers, and demultiplexers; Optical design; Optical fiber theory; Optics; Physics; Resonators; Spectra; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Radiation quality; Theoretical study; Optical communication; Wavelength division multiplexing; External cavity; Laser arrays; Fiber lasers; Beam combining
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/3.998614

We model the spectral beam combining of a fiber laser array in the external resonator configuration, as proposed by V. Daneu et al. A diffraction integral-based approach is used that leads to design principles for most significant measures of performance, such as efficiency, bandwidth, and beam quality. Sensitivity to alignment and positioning errors is also characterized. Off-axis transform lens aberrations are shown to limit array size, and two design criteria are applied to compare the performance of simple spherical, compound, and aspheric lenses. The results indicate that a simple aspheric lens is superior in meeting the proposed criteria to a well-designed compound (quadruplet) lens with spherical surfaces. Application to the efficient coupling of a laser array to a multimode fiber core is discussed as a final example.