Perturbative analysis of coherent combining efficiency with mismatched lasers

Goodno, Gregory D.; Shih, Chun-Ching; Rothenberg, Joshua E.

doi:10.1364/oe.18.025403

Cited by 134 publications

(72 citation statements)

References 14 publications

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“…The phase-locking efficiency γ (as defined in equation (2)) reaches 97%, and is equal in that configuration to the combining efficiency η P on the P arm of the interferometer. It is limited by the residual mismatch between the two beam profiles [10]. Under phase-locked operation, the laser line is narrow (<25 pm) and corresponds to the single-frequency operation of both lasers in the external cavity, as expected.…”

Section: Phase-locking On the Back Sidesupporting

confidence: 65%

“…Such a high visibility demonstrates that the coherence between the two lasers beams is extremely good. Thus, the poor combining efficiency achieved is only limited by the wavefront and intensity mismatches between the two laser beam profiles [10]. We are currently investigating these limitations.…”

Section: Phase-locking and Coherent Combining Of Two Tapered Lasersmentioning

confidence: 99%

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Separate phase-locking and coherent combining of two laser diodes in a Michelson cavity

Schimmel

Doyen

Janicot

et al. 2015

High-Power Diode Laser Technology and Applications XIII

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We describe a new coherent beam combining architecture based on passive phase-locking of two laser diodes in a Michelson external cavity on their rear facet, and their coherent combination on the front facet. As a proof-of-principle, two ridge lasers have been coherently combined with >90 % efficiency. The phase-locking range, and the resistance of the external cavity to perturbations have been thoroughly investigated. The combined power has been stabilized over more than 15 min with an optical feedback as well as with an automatic adjustment of the driving currents. Furthermore, two high-brightness high-power tapered laser diodes have been coherently combined in a similar arrangement; the combining efficiency is 70% and results in an output power of 4 W. We believe that this new configuration combines the simplicity of passive self-organizing architectures with the optical efficiency of master-oscillator power-amplifier ones.

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Section: Phase-locking On the Back Sidesupporting

confidence: 65%

Section: Phase-locking and Coherent Combining Of Two Tapered Lasersmentioning

confidence: 99%

Separate phase-locking and coherent combining of two laser diodes in a Michelson cavity

Schimmel

Doyen

Janicot

et al. 2015

High-Power Diode Laser Technology and Applications XIII

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“…21 With this system 530 W of average power and a pulse energy of 1.3 mJ have been realized with combining efficiencies exceeding 93%. Furthermore, it has also been theoretically shown 22,23 that the efficiency can be kept high even up to more than thousand channels. These promising experimental results have encouraged research into particle acceleration based on the coherent combination of a large number (possibly millions) of fibre amplifiers.…”

Section: Introductionmentioning

confidence: 96%

A concept for multiterawatt fibre lasers based on coherent pulse stacking in passive cavities

et al. 2014

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Since the advent of femtosecond lasers, performance improvements have constantly impacted on existing applications and enabled novel applications. However, one performance feature bearing the potential of a quantum leap for high-field applications is still not available: the simultaneous emission of extremely high peak and average powers. Emerging applications such as laser particle acceleration require exactly this performance regime and, therefore, challenge laser technology at large. On the one hand, canonical bulk systems can provide pulse peak powers in the multi-terawatt to petawatt range, while on the other hand, advanced solid-state-laser concepts such as the thin disk, slab or fibre are well known for their high efficiency and their ability to emit high average powers in the kilowatt range with excellent beam quality. In this contribution, a compact laser system capable of simultaneously providing high peak and average powers with high wall-plug efficiency is proposed and analysed. The concept is based on the temporal coherent combination (pulse stacking) of a pulse train emitted from a high-repetition-rate femtosecond laser system in a passive enhancement cavity. Thus, the pulse energy is increased at the cost of the repetition rate while almost preserving the average power. The concept relies on a fast switching element for dumping the enhanced pulse out of the cavity. The switch constitutes the key challenge of our proposal. Addressing this challenge could, for the first time, allow the highly efficient dumping of joule-class pulses at megawatt average power levels and lead to unprecedented laser parameters.

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“…We note that the overall combining efficiency is constrained by the cumulative effect of various aberrations and mismatches between the fiber amplifiers. 12 For example, the 1 × 5 DOE has an intrinsic splitter loss of ∼5% when used as a combiner, with the remaining power diffracted into the higher orders. This is due to the low DOE channel count where there are less degrees of freedom to optimize the phase profile.…”

Section: Multi-kilowatt Beam Combining Resultsmentioning

confidence: 99%

Multi-kilowatt diffractive coherent combining of pseudorandom-modulated fiber amplifiers

et al. 2016

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Abstract. We report efficient coherent beam combining of five kW-class fiber amplifiers seeded with pseudorandom phase-modulated light, using a 1 × 5 diffractive optical element (DOE). Each fiber amplifier channel was path length matched, actively polarized, and provided approximately 1.2 kW of near diffraction-limited output power (M 2 < 1.1). A low-power sample of the combined beam after the DOE provided an error signal for active phase stabilization. After phase stabilization, the beams were coherently combined via the DOE. Notably, a total output power of ∼5 kW was achieved with 82% combining efficiency and excellent beam quality (M 2 < 1.1). The intrinsic DOE splitter loss was 5%. Additional losses due in part to nonideal polarization, amplified spontaneous emission content, uncorrelated wavefront errors, and fractional beam misalignments contributed to the efficiency reduction. Overall, multi-kW beam combining of pseudorandom-modulated fiber amplifiers was demonstrated for the first time.

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Perturbative analysis of coherent combining efficiency with mismatched lasers

Cited by 134 publications

References 14 publications

Separate phase-locking and coherent combining of two laser diodes in a Michelson cavity

Separate phase-locking and coherent combining of two laser diodes in a Michelson cavity

A concept for multiterawatt fibre lasers based on coherent pulse stacking in passive cavities

Multi-kilowatt diffractive coherent combining of pseudorandom-modulated fiber amplifiers

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