Ultrafast non-equilibrium carrier dynamics in semiconductor laser mode-locking

Hader, J.; Scheller, Maik; Laurain, Alexandre; Kilen, I.; Baker, Carol S.; Moloney, Jerome V.; Koch, S. W.

doi:10.1088/0268-1242/32/1/013002

Cited by 23 publications

(9 citation statements)

References 54 publications

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“…FCN), time-resolved Z-scan measurements would be required40 . In addition, the variation of the probe-pulse duration while maintaining equivalent peak powers could provide insight into the nature of the carrier dynamics including the effect of non-equilibrium many-body effects, which become important at sub-ps time-scales41 . This will be the subject of our future work.If BEKE is the dominating contribution to the nonlinear lensing, self-mode-locking of VECSELs has to be modeled by substituting the slow, highly nonlinear saturable absorber term with a fast saturable C. Kriso et al (2018) 10 absorber term in the common mode-locking model42 (c.f.Figure 4bon pulse shaping).…”

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confidence: 99%

Microcavity-enhanced Kerr nonlinearity in a vertical-external-cavity surface-emitting laser

Kriso¹,

Kress²,

Munshi³

et al. 2019

Opt. Express

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Self-mode-locking has become an emerging path to the generation of ultrashort pulses with vertical-external-cavity surface-emitting lasers. In our work, a strong Kerr nonlinearity that is so far assumed to give rise to mode-locked operation is evidenced and a strong nonlinearity enhancement by the microcavity is revealed. We present wavelength-dependent measurements of the nonlinear absorption and nonlinear-refractive-index change in a gain chip using the Z-scan technique. We report negative nonlinear refraction up to 1.5⋅10 -11 cm 2 /W in magnitude in the (InGa)As/Ga(AsP) material system close to the laser design wavelength, which can lead to Kerr lensing. We show that by changing the angle of incidence of the probe beam with respect to the gain chip, the Kerr nonlinearity can be wavelength-tuned, shifting with the microcavity resonance.Such findings may ultimately lead to novel concepts with regard to tailored self-mode-locking behavior achievable by peculiar Kerr-lens chip designs for cost-effective, robust and compact fspulsed semiconductor lasers.The Kerr effect is at the basis of many important device concepts like all-optical switching 1 , optical limiting 2 and soliton mode-locking of lasers and microresonators 3,4 . The capability to accurately measure and model the nonlinear refractive index changes associated with the Kerr effect is crucial for improved device operation, where a specifically tailored nonlinear refractive index is required, e.g. for the intensity-dependent Kerr lensing. Several measurement schemes have been developed in the past for the characterization of the nonlinear refractive index 5-7 , with the Z-scan technique 8 being undoubtedly the most prominent one due to its simplicity and high sensitivity. This method continues to be of high experimental value with the rise of novel material classes like graphene and other two-dimensional semiconductors which often exhibit a very strong refractive nonlinearity 9-11 .Kerr-lens mode-locked Ti:Sapphire lasers have dominated the field of ultra-short high-power modelocked lasers since their initial discovery nearly three decades ago 12,13 . In these lasers, the intensitydependent refractive index of the gain crystal leads to self-focusing of the laser beam for high intensities. When part of the continuous-wave (cw) beam profile is suppressed by inserting a slit into C. Kriso et al. (2018) 2

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confidence: 99%

Microcavity-enhanced Kerr nonlinearity in a vertical-external-cavity surface-emitting laser

Kriso¹,

Kress²,

Munshi³

et al. 2019

Opt. Express

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“…The characteristic timescale for gain recovery is on the order of tens of picoseconds or longer, which is orders of magnitudes slower than the carrier scattering [46]. Numerical tests show that the details of the results are not critically sensitive on the exact choice of τ scatt .…”

Section: Microscopic Theorymentioning

confidence: 93%

Non-equilibrium dynamics in the dual-wavelength operation of vertical external-cavity surface-emitting lasers

et al. 2019

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Microscopic many-body theory coupled to MaxwellâĂŹs equation is used to investigate dual-wavelength operation in vertical external-cavity surface-emitting lasers. The intrinsically dynamic nature of coexisting emission wavelengths in semiconductor lasers is associated with characteristic non-equilibrium carrier dynamics which causes significant deformations of the quasi-equilibrium gain and carrier inversion. Extended numerical simulations are employed to efficiently investigate the parameter space to identify the regime for two-wavelength operation. Using an frequency selective intracavity etalon, two families of modes are stabilized with dynamical interchange of the strongest emission peaks. For this operation mode, anti-correlated intensity noise is observed in agreement with the experiment. A method using effective frequency selective filtering is suggested for stabilization genuine dual-wavelength output.

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“…Through systematic numerical simulations we have found that the final mode locked pulse can be one of four different types 18,22 : a stable and an unstable single pulse, an unstable pulse molecule or multiple pulses. For a single stable pulse, there is only one pulse propagating in the cavity and the output has constant amplitude and FWHM.…”

Section: Pulse Familymentioning

confidence: 99%

Non-equilibrium effects in VECSELs

et al. 2017

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A systematic study of microscopic many-body dynamics is used to analyze a strategy for how to generate ultrashort mode locked pulses in the vertical external-cavity surface-emitting lasers with a saturable absorber mirror. The field propagation is simulated using Maxwell's equations and is coupled to the polarization from the quantum wells using the semiconductor Bloch equations. Simulations on the level of second Born-Markov are used to fit coefficients for microscopic higher order correlation effects such as dephasing of the polarization, carrier-carrier scattering and carrier relaxation. We numerically examine recent published experimental results on mode locked pulses, as well as the self phase modulation in the gain chip and SESAM.

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Ultrafast non-equilibrium carrier dynamics in semiconductor laser mode-locking

Cited by 23 publications

References 54 publications

Microcavity-enhanced Kerr nonlinearity in a vertical-external-cavity surface-emitting laser

Microcavity-enhanced Kerr nonlinearity in a vertical-external-cavity surface-emitting laser

Non-equilibrium dynamics in the dual-wavelength operation of vertical external-cavity surface-emitting lasers

Non-equilibrium effects in VECSELs

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