Multi-kilowatt power scaling and coherent beam combining of narrow-linewidth fiber lasers

Dajani, Iyad; Flores, Angel; Holten, Roger; Anderson, Brian; Pulford, Benjamin; Ehrenreich, T.

doi:10.1117/12.2218216

Cited by 36 publications

(22 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Narrow-linewidth, high-power fiber amplifiers are needed for both coherent and incoherent beam combining or for spectral combining of multiple amplifiers. For coherent beam combining, a narrower linewidth improves combining efficiency in the presence of path length mismatch [1], allows higher angle beam steering, and enables better wavefront predistortion [2]. For the type of spectral beam combining in which a grating is the output coupler, a narrower linewidth reduces the output beam spreading due to diffraction.…”

Section: Introductionmentioning

confidence: 99%

Seeding fiber amplifiers with piecewise parabolic phase modulation for high SBS thresholds and compact spectra

et al. 2019

View full text Add to dashboard Cite

We propose using piecewise parabolic phase modulation of the seed laser for suppressing stimulated Brillouin scattering (SBS) in a fiber amplifier. Simulations are run with a 9 m passive fiber. Compared with random phase modulation and 0-π pseudo-random phase modulation, the piecewise parabolic phase waveform yields a higher SBS threshold per unit bandwidth. If the bandwidth is defined as the range of frequencies containing 85% of the total power, the threshold for parabolic phase modulation is 1.4 times higher than the threshold for the five-or seven-bit pseudo-random modulation format. If the bandwidth is defined more tightly, e.g., the range of frequencies containing 95% of the total power, the threshold for parabolic phase modulation is three times higher. For both cases, achieving a bandwidth of 1.5 GHz requires a maximum phase shift of ~30 radians. All of the waveforms are compared on the basis of the bandwidth required of the phase moduator. The coherence functions are calculated in order to compare their suitability for coherent combining.

show abstract

Section: Introductionmentioning

confidence: 99%

Seeding fiber amplifiers with piecewise parabolic phase modulation for high SBS thresholds and compact spectra

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Narrow Linewidth fiber laser systems, which have earned a solid reputation as a highly power scalable laser with excellent beam quality, are attractive sources for many applications, such as coherent lidar systems, nonlinear frequency conversion, and coherent/spectral beam combining architectures [1][2][3][4]. As the output power of fiber lasers grows into the multihundred range, detrimental nonlinear effects such as the stimulated Brillouin scattering (SBS) and the self-phase modulation (SPM) become the major limit factors that preclude further power upscaling [5]. Low numerical aperture (NA), large mode area (LMA) step index fiber designs, which support only a few modes in the core, have been employed to overcome the limitation of the nonlinear effects while maintaining a high beam quality of the output laser [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

M2 factor for evaluating fiber lasers from large mode area few-mode fibers

Tao

Huang²,

Li³

et al. 2023

Front. Phys.

View full text Add to dashboard Cite

Evaluating the laser quality accurately is one of the most important and fundamental physical issues for laser sources, and the beam quality of lasers from the large mode area few-mode fibers have been haunted by the presence of high order mode for many years. This paper presents a modification to the M2 factor, which can be used to evaluate the mode content of fiber lasers accurately and efficiently, no matter whether the fiber modes are superposited coherently or incoherently. By mathematical derivation, the origin of the influence of relative phase on the M2 factor has been determined mathematically. A modification to the second moment of the beam intensity profile has been proposed, which eliminates the impact of uncontrollable relative phase on the second moment, and subsequently restores the one-to-one mapping between mode content and M2 factor even for coherent superposition cases. Also presented are the results of numerical simulations, which support the validity of the modified M2 factor to evaluate the mode content of the high power fiber lasers. With modified M2 factor being less than 1.1, the power fraction of LP11 mode content is unique and determined to be less than 3%.

show abstract

“…With the rapid development of double clad fiber manufacture craft and high brightness laser diode pump sources, the output powers have soared up to multi-kilowatt [4][5][6], and a 10kW single mode fiber laser has been reported in 2009 [7]. However, due to the accumulated heat load at high average power, severe dynamic mode coupling -mode instabilityhas been triggered in the fiber lasers [8,9], which is the physical manifest of stimulated thermal Rayleigh scattering in fiber, and currently limits the power scaling and application area expanding of fiber laser systems [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Static and dynamic mode evolution in high-power distributed side-coupled cladding-pumped fiber amplifiers

Tao

Liu

Xie

et al. 2021

High Pow Laser Sci Eng

View full text Add to dashboard Cite

We present a theoretical study of mode evolution in high power distributed sidecoupled cladding-pumped (DSCCP) fiber amplifiers. A semi-analytical model taking the side pumping schemes, transverse mode competition and stimulated thermal Rayleigh scattering into consideration has been built, which can model the static and dynamic mode evolution in high power DSCCP fiber amplifiers. The mode evolution behavior has been investigated with variation of fiber amplifier parameters, such as the pump power distribution, the length of the DSCCP fiber, the averaged coupling coefficient, the number of the pump cores, and the arrangement of pump cores. Interestingly, it revealed that static mode evolution induced by transverse mode competition is different from the dynamic ones induced by stimulated thermal Rayleigh scattering. It shows that the high order mode experiences slightly higher gain in DSCCP fiber amplifiers, but the mode instability thresholds for DSCCP fiber amplifiers are higher than those end-coupled counterparts. By increasing the pump core number and reducing the averaged coupling coefficient, the mode instability threshold can be increased, which

show abstract

Multi-kilowatt power scaling and coherent beam combining of narrow-linewidth fiber lasers

Cited by 36 publications

References 5 publications

Seeding fiber amplifiers with piecewise parabolic phase modulation for high SBS thresholds and compact spectra

Seeding fiber amplifiers with piecewise parabolic phase modulation for high SBS thresholds and compact spectra

M2 factor for evaluating fiber lasers from large mode area few-mode fibers

Static and dynamic mode evolution in high-power distributed side-coupled cladding-pumped fiber amplifiers

Contact Info

Product

Resources

About