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Free-carrier-induced soliton fission unveiled by in situ measurements in nanophotonic waveguides.

Husko C, Wulf M, Lefrancois S, Combrié S, Lehoucq G, De Rossi A, Eggleton BJ, Kuipers L - Nat Commun (2016)

Bottom Line: We develop an analytic formalism describing the free-carrier dispersion (FCD) perturbation and show the experiment exceeds the minimum threshold by an order of magnitude.We confirm these observations with a numerical nonlinear Schrödinger equation model.These results provide a fundamental explanation and physical scaling of optical pulse evolution in free-carrier media and could enable improved supercontinuum sources in gas based and integrated semiconductor waveguides.

View Article: PubMed Central - PubMed

Affiliation: Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and Optical Science (IPOS), School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.

ABSTRACT
Solitons are localized waves formed by a balance of focusing and defocusing effects. These nonlinear waves exist in diverse forms of matter yet exhibit similar properties including stability, periodic recurrence and particle-like trajectories. One important property is soliton fission, a process by which an energetic higher-order soliton breaks apart due to dispersive or nonlinear perturbations. Here we demonstrate through both experiment and theory that nonlinear photocarrier generation can induce soliton fission. Using near-field measurements, we directly observe the nonlinear spatial and temporal evolution of optical pulses in situ in a nanophotonic semiconductor waveguide. We develop an analytic formalism describing the free-carrier dispersion (FCD) perturbation and show the experiment exceeds the minimum threshold by an order of magnitude. We confirm these observations with a numerical nonlinear Schrödinger equation model. These results provide a fundamental explanation and physical scaling of optical pulse evolution in free-carrier media and could enable improved supercontinuum sources in gas based and integrated semiconductor waveguides.

No MeSH data available.


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Comparison of experiment and model of the nonlinear pulse propagation.(a,b) Time-resolved NSOM measurements and GNLSE modelling at a peak power of at a peak power of 0.5 W at a propagation distance of (a) 250 μm and (b) 700 μm. Temporal broadening of the pulse envelope due to GVD is visible in experiment (red line) and the model (blue line). (c,d) Same as above with a peak power of 5.9 W. The multiple peaks characteristic of soliton fission are clearly observable in both theory and experiment. To illustrate that the main features observed in the experiment are related to free-carrier generation, (e,f) compare the experimental results with GNLSE modelling results (green line) taking only the soliton terms and FCD/3PA into account, which still results in a good agreement. Note here we show the cross-correlation of the electric field of the temporal pulse envelope for the modelling as well as the experimental results as defined in the Methods.
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f2: Comparison of experiment and model of the nonlinear pulse propagation.(a,b) Time-resolved NSOM measurements and GNLSE modelling at a peak power of at a peak power of 0.5 W at a propagation distance of (a) 250 μm and (b) 700 μm. Temporal broadening of the pulse envelope due to GVD is visible in experiment (red line) and the model (blue line). (c,d) Same as above with a peak power of 5.9 W. The multiple peaks characteristic of soliton fission are clearly observable in both theory and experiment. To illustrate that the main features observed in the experiment are related to free-carrier generation, (e,f) compare the experimental results with GNLSE modelling results (green line) taking only the soliton terms and FCD/3PA into account, which still results in a good agreement. Note here we show the cross-correlation of the electric field of the temporal pulse envelope for the modelling as well as the experimental results as defined in the Methods.

Mentions: The nonlinear pulse propagation in the GaInP semiconductor waveguide can be described by a GNLSE model (Supplementary Note 3). The nonlinear dynamics here are dominated by the χ(3) optical Kerr effect (nonlinear parameter γ) with free carriers generated by nonlinear three-photon absorption (3PA, α3) acting as a perturbation in the wide-gap material (Eg=1.9 eV) for our 1,553 nm (∼0.8 eV) pulses (ref. 12). Figure 2a–f show detailed GNLSE modelling (dashed blue and green) with the experimental data (solid red) from Fig. 1 superimposed. In particular, we highlight (a),(b) low and (c),(d) high power at the propagation distance of 250 and 700 μm, respectively. The temporal shapes are in good quantitative agreement and excellent qualitative agreement with the experimental data and capture the essential physics of the nonlinear pulse propagation in the nanophotonic waveguide. The good agreement between the experiment and the GNLSE model is even conserved if only the free-carrier effects are included as perturbation to the soliton propagation, as presented in Fig. 2e,f. These results indicate FCD is the dominant perturbation and the cause of the soliton fission. We now perform additional GNLSE modelling to verify this observation and to examine the physical origin of the fission.


Free-carrier-induced soliton fission unveiled by in situ measurements in nanophotonic waveguides.

Husko C, Wulf M, Lefrancois S, Combrié S, Lehoucq G, De Rossi A, Eggleton BJ, Kuipers L - Nat Commun (2016)

Comparison of experiment and model of the nonlinear pulse propagation.(a,b) Time-resolved NSOM measurements and GNLSE modelling at a peak power of at a peak power of 0.5 W at a propagation distance of (a) 250 μm and (b) 700 μm. Temporal broadening of the pulse envelope due to GVD is visible in experiment (red line) and the model (blue line). (c,d) Same as above with a peak power of 5.9 W. The multiple peaks characteristic of soliton fission are clearly observable in both theory and experiment. To illustrate that the main features observed in the experiment are related to free-carrier generation, (e,f) compare the experimental results with GNLSE modelling results (green line) taking only the soliton terms and FCD/3PA into account, which still results in a good agreement. Note here we show the cross-correlation of the electric field of the temporal pulse envelope for the modelling as well as the experimental results as defined in the Methods.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835551&req=5

f2: Comparison of experiment and model of the nonlinear pulse propagation.(a,b) Time-resolved NSOM measurements and GNLSE modelling at a peak power of at a peak power of 0.5 W at a propagation distance of (a) 250 μm and (b) 700 μm. Temporal broadening of the pulse envelope due to GVD is visible in experiment (red line) and the model (blue line). (c,d) Same as above with a peak power of 5.9 W. The multiple peaks characteristic of soliton fission are clearly observable in both theory and experiment. To illustrate that the main features observed in the experiment are related to free-carrier generation, (e,f) compare the experimental results with GNLSE modelling results (green line) taking only the soliton terms and FCD/3PA into account, which still results in a good agreement. Note here we show the cross-correlation of the electric field of the temporal pulse envelope for the modelling as well as the experimental results as defined in the Methods.
Mentions: The nonlinear pulse propagation in the GaInP semiconductor waveguide can be described by a GNLSE model (Supplementary Note 3). The nonlinear dynamics here are dominated by the χ(3) optical Kerr effect (nonlinear parameter γ) with free carriers generated by nonlinear three-photon absorption (3PA, α3) acting as a perturbation in the wide-gap material (Eg=1.9 eV) for our 1,553 nm (∼0.8 eV) pulses (ref. 12). Figure 2a–f show detailed GNLSE modelling (dashed blue and green) with the experimental data (solid red) from Fig. 1 superimposed. In particular, we highlight (a),(b) low and (c),(d) high power at the propagation distance of 250 and 700 μm, respectively. The temporal shapes are in good quantitative agreement and excellent qualitative agreement with the experimental data and capture the essential physics of the nonlinear pulse propagation in the nanophotonic waveguide. The good agreement between the experiment and the GNLSE model is even conserved if only the free-carrier effects are included as perturbation to the soliton propagation, as presented in Fig. 2e,f. These results indicate FCD is the dominant perturbation and the cause of the soliton fission. We now perform additional GNLSE modelling to verify this observation and to examine the physical origin of the fission.

Bottom Line: We develop an analytic formalism describing the free-carrier dispersion (FCD) perturbation and show the experiment exceeds the minimum threshold by an order of magnitude.We confirm these observations with a numerical nonlinear Schrödinger equation model.These results provide a fundamental explanation and physical scaling of optical pulse evolution in free-carrier media and could enable improved supercontinuum sources in gas based and integrated semiconductor waveguides.

View Article: PubMed Central - PubMed

Affiliation: Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and Optical Science (IPOS), School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.

ABSTRACT
Solitons are localized waves formed by a balance of focusing and defocusing effects. These nonlinear waves exist in diverse forms of matter yet exhibit similar properties including stability, periodic recurrence and particle-like trajectories. One important property is soliton fission, a process by which an energetic higher-order soliton breaks apart due to dispersive or nonlinear perturbations. Here we demonstrate through both experiment and theory that nonlinear photocarrier generation can induce soliton fission. Using near-field measurements, we directly observe the nonlinear spatial and temporal evolution of optical pulses in situ in a nanophotonic semiconductor waveguide. We develop an analytic formalism describing the free-carrier dispersion (FCD) perturbation and show the experiment exceeds the minimum threshold by an order of magnitude. We confirm these observations with a numerical nonlinear Schrödinger equation model. These results provide a fundamental explanation and physical scaling of optical pulse evolution in free-carrier media and could enable improved supercontinuum sources in gas based and integrated semiconductor waveguides.

No MeSH data available.


Related in: MedlinePlus