Coherent array of 900 semiconductor laser amplifiers

Levy, Joseph L.; Roh, Kun

doi:10.1117/12.208463

Cited by 16 publications

(7 citation statements)

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“…To our knowledge, this is the first demonstration of CBC of high brightness semiconductor amplifiers in QCW mode. This experiment underlines the advantage of the use of tapered amplifiers for CBC architectures, as the combined power per element compares favorably to previous demonstrations of CBC of other types of semiconductor lasers and amplifiers [23][24][25] . Scaling to even higher currents is currently limited by degraded pulse stability caused by self lasing of the amplifiers.…”

Section: Cbc In Quasi Continous Wave Operationsupporting

confidence: 70%

Recent progress in brightness scaling by coherent beam combining of tapered amplifiers for efficient high power frequency doubling

Albrodt

Jamal²,

Hansen³

et al. 2019

High-Power Diode Laser Technology XVII

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High brightness diode laser beam combining techniques are in demand for efficient high power nonlinear conversion. Coherent beam combining (CBC) is the only method that has the potential for brightness scaling by maintaining one single narrow spectral linewidth. CBC in a master oscillator power amplifier (MOPA) configuration using a small number of efficiently cooled tapered amplifiers is a promising approach for efficient brightness scaling in a simple architecture. We present the application of such a source based on CBC of three tapered amplifiers seeded by a DFB laser at λ = 976 nm for second harmonic generation (SHG). A maximum power of 2.1 W at 488 nm was generated by SHG in a MgO:PPLN bulk crystal limited by thermal effects. A clear benefit of the beam clean-up resulting from the CBC setup was documented leading to an improved nonlinear efficiency. As part of our ongoing studies into further brightness scaling in CBC architectures, we present an experimental analysis of the phase dynamics of tapered amplifiers in quasi continuous operation (QCW) at high currents. Furthermore, we are investigating different amplifier designs for improved beam quality at high powers and therefore improved combining efficiency.

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Section: Cbc In Quasi Continous Wave Operationsupporting

confidence: 70%

Recent progress in brightness scaling by coherent beam combining of tapered amplifiers for efficient high power frequency doubling

Albrodt

Jamal²,

Hansen³

et al. 2019

High-Power Diode Laser Technology XVII

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“…CBC of arrays of diode lasers in an external cavity [17][18][19] has been demonstrated but did not lead to a significant increase of the available NIR power since the combined power was limited to a few watts. CBC in MOPA configuration has been demonstrated for larger arrays of amplifiers [20,21] and led to a significant increase of the available NIR power of diode laser architectures reaching about 40 W for CBC of 47 Slab Coupled Optical Waveguide Amplifiers (SCOWA) [22].…”

Section: Coherent Beam Combiningmentioning

confidence: 99%

Coherent combining of high brightness tapered amplifiers for efficient non-linear conversion

Albrodt¹,

Jamal²,

Hansen³

et al. 2019

Opt. Express

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We report on a coherent beam combination of three high-brightness tapered amplifiers, which are seeded by a single-frequency laser at λ = 976 nm in a simple architecture with efficiently cooled emitters. The maximal combined power of 12.9 W is achieved at a combining efficiency of > 65%, which is limited by the amplifiers' intrinsic beam quality. The coherent combination cleans up the spatial profile, as the central lobe's power content increases by up to 86%. This high-brightness infrared beam is converted into the visible by second harmonic generation. This results in a high non-linear conversion efficiency of 4.5%/W and a maximum power over 2 W at 488 nm, which is limited by thermal effects in the periodically poled lithium niobate (PPLN).

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“…Perhaps the simplest methods for cophasing beams are to maximize the combined power in the far-field central lobe using hill climbing algorithms [19,28], among which the most widely used is the stochastic parallel gradient descent (SPGD) method [29]. In these approaches, the phases of the entire array of beams are simultaneously changed by small, statistically uncorrelated amounts, and the corresponding change in far-field power (or combining efficiency) is sensed.…”

Section: Hill Climbingmentioning

confidence: 99%

“…Consequently, closed-loop bandwidths drop proportionately to 1/N [19,21]. Hence, it is an attractive path for systems with either low channel counts (N ( 100) or low phase noise amplifiers that do not require high-speed phase control [28]. Hence, it is an attractive path for systems with either low channel counts (N ( 100) or low phase noise amplifiers that do not require high-speed phase control [28].…”

Section: Hill Climbingmentioning

confidence: 99%

Engineering of Coherently Combined, High‐Power Laser Systems

Goodno

Rothenberg

2013

Coherent Laser Beam Combining

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In recent years, much effort has been expended toward scaling electric lasers to CW power levels on the order of 100 kW or greater [1]. The key challenge in such scaling is maintaining near-diffraction-limited (DL) beam quality (BQ) to enable tight focusing onto a distant target. Despite the maturation of scalable, diode-pumped laser amplifier technologies such as zigzag slabs [2] or fibers [3], thermal effects or optical nonlinearities currently limit near-DL output from single lasers to an order of magnitude lower power, around 10 kW.Actively phase-locked coherent beam combination (CBC) of N laser amplifiers seeded by a common master oscillator (MO) represents an engineerable approach toward scaling laser brightness B (loosely defined here as B $ power/BQ 2 ) beyond the limits of the underlying single-element laser technology. Ideally, the combined output behaves as if it were a single beam, and B is thereby increased by a factor of N over an unphased array or by a factor of N 2 over any individual laser [4].A compelling architectural advantage of CBC systems in comparison to singleaperture lasers of comparable power is the graceful degradation in response to failure of any gain element. This feature can be elucidated from the scaling of B $ N 2 , so the relative rate of change in brightness as individual lasers fail is 1/B(dB/dN) ¼ 2/N. Hence, for large arrays, the drop in brightness is gradual. For example, failure of 1 out of N ¼ 100 lasers would still allow a CBC system to continue operating at 98% of its original brightness.Active CBC with servo-based phase locking can be straightforwardly engineered for very high channel counts and for very high-power laser gain elements. Recently, Northrop Grumman Aerospace Systems adopted an actively phaselocked approach to combine seven 15 kW Nd:YAG slab amplifier chains to demonstrate the world's first 100 kW electric laser with record-setting brightness [5]. As of this writing, work is underway to extend this technology to achieve similar power levels in a CBC array of fiber lasers with improved BQ and efficiency as well as reduced size and weight [6,7].

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Coherent array of 900 semiconductor laser amplifiers

Cited by 16 publications

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Recent progress in brightness scaling by coherent beam combining of tapered amplifiers for efficient high power frequency doubling

Recent progress in brightness scaling by coherent beam combining of tapered amplifiers for efficient high power frequency doubling

Coherent combining of high brightness tapered amplifiers for efficient non-linear conversion

Engineering of Coherently Combined, High‐Power Laser Systems

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