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Observation of optical solitons in PT-symmetric lattices.

Wimmer M, Regensburger A, Miri MA, Bersch C, Christodoulides DN, Peschel U - Nat Commun (2015)

Bottom Line: Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation.Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions.The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute of Optics, Information and Photonics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 7/B2, 91058 Erlangen, Germany [2] Erlangen Graduate School in Advanced Optical Technologies (SAOT), 91058 Erlangen, Germany.

ABSTRACT
Controlling light transport in nonlinear active environments is a topic of considerable interest in the field of optics. In such complex arrangements, of particular importance is to devise strategies to subdue chaotic behaviour even in the presence of gain/loss and nonlinearity, which often assume adversarial roles. Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation. Here we report the experimental observation of optical solitons in PT-symmetric lattices. Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions. The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated.

No MeSH data available.


Synthesizing a saturable absorber.A single-lattice site is excited in a PT-symmetric lattice with ϕ0=0.4π, G=2 involving a global loss of 5%. In the linear regime the attenuation filters out all low-level noise signals (a,d). If the power is increased (b,e), the nonlinear mode starts to localize and experiences a lower loss during propagation by choosing the best path (c,f). At high powers losses can even be avoided and gain can be globally reached. (g–i) shows the energy from the measured data in both loops (blue), in the long loop (green) and in the short loop (red). While in the experiment the power of the initial pulse is varied, in the simulation nonlinear factors of Γ=0, Γ=0.26π and Γ=0.52π were assumed for a best fit between simulation and experiment.
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f7: Synthesizing a saturable absorber.A single-lattice site is excited in a PT-symmetric lattice with ϕ0=0.4π, G=2 involving a global loss of 5%. In the linear regime the attenuation filters out all low-level noise signals (a,d). If the power is increased (b,e), the nonlinear mode starts to localize and experiences a lower loss during propagation by choosing the best path (c,f). At high powers losses can even be avoided and gain can be globally reached. (g–i) shows the energy from the measured data in both loops (blue), in the long loop (green) and in the short loop (red). While in the experiment the power of the initial pulse is varied, in the simulation nonlinear factors of Γ=0, Γ=0.26π and Γ=0.52π were assumed for a best fit between simulation and experiment.

Mentions: Finally, we discuss the possibility of using such PT synthetic nonlinear lattices as a new class of saturable absorbers63. This is achieved by adding a global loss to an otherwise PT-symmetric nonlinear mesh lattice. When a low-intensity pulse is injected into this system, it spreads linearly while all modes decay due to the added loss (Fig. 7a,d). As a result after several round-trips the total energy of the system vanishes. On the other hand, by increasing the power of the injected pulse, a self-trapped wavepacket forms which experiences much lower losses compared with a linearly diffracting wave (Fig. 7b,e). By further increasing the power of the input pulse, this localized wave can even amplify itself (Fig. 7c,f). Such a behaviour of nonlinear waves646566 is strongly related to saturable absorbers that are widely used in Q-switched laser cavities and in ultra-short optical pulse arrangements676869.


Observation of optical solitons in PT-symmetric lattices.

Wimmer M, Regensburger A, Miri MA, Bersch C, Christodoulides DN, Peschel U - Nat Commun (2015)

Synthesizing a saturable absorber.A single-lattice site is excited in a PT-symmetric lattice with ϕ0=0.4π, G=2 involving a global loss of 5%. In the linear regime the attenuation filters out all low-level noise signals (a,d). If the power is increased (b,e), the nonlinear mode starts to localize and experiences a lower loss during propagation by choosing the best path (c,f). At high powers losses can even be avoided and gain can be globally reached. (g–i) shows the energy from the measured data in both loops (blue), in the long loop (green) and in the short loop (red). While in the experiment the power of the initial pulse is varied, in the simulation nonlinear factors of Γ=0, Γ=0.26π and Γ=0.52π were assumed for a best fit between simulation and experiment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525206&req=5

f7: Synthesizing a saturable absorber.A single-lattice site is excited in a PT-symmetric lattice with ϕ0=0.4π, G=2 involving a global loss of 5%. In the linear regime the attenuation filters out all low-level noise signals (a,d). If the power is increased (b,e), the nonlinear mode starts to localize and experiences a lower loss during propagation by choosing the best path (c,f). At high powers losses can even be avoided and gain can be globally reached. (g–i) shows the energy from the measured data in both loops (blue), in the long loop (green) and in the short loop (red). While in the experiment the power of the initial pulse is varied, in the simulation nonlinear factors of Γ=0, Γ=0.26π and Γ=0.52π were assumed for a best fit between simulation and experiment.
Mentions: Finally, we discuss the possibility of using such PT synthetic nonlinear lattices as a new class of saturable absorbers63. This is achieved by adding a global loss to an otherwise PT-symmetric nonlinear mesh lattice. When a low-intensity pulse is injected into this system, it spreads linearly while all modes decay due to the added loss (Fig. 7a,d). As a result after several round-trips the total energy of the system vanishes. On the other hand, by increasing the power of the injected pulse, a self-trapped wavepacket forms which experiences much lower losses compared with a linearly diffracting wave (Fig. 7b,e). By further increasing the power of the input pulse, this localized wave can even amplify itself (Fig. 7c,f). Such a behaviour of nonlinear waves646566 is strongly related to saturable absorbers that are widely used in Q-switched laser cavities and in ultra-short optical pulse arrangements676869.

Bottom Line: Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation.Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions.The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute of Optics, Information and Photonics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 7/B2, 91058 Erlangen, Germany [2] Erlangen Graduate School in Advanced Optical Technologies (SAOT), 91058 Erlangen, Germany.

ABSTRACT
Controlling light transport in nonlinear active environments is a topic of considerable interest in the field of optics. In such complex arrangements, of particular importance is to devise strategies to subdue chaotic behaviour even in the presence of gain/loss and nonlinearity, which often assume adversarial roles. Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation. Here we report the experimental observation of optical solitons in PT-symmetric lattices. Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions. The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated.

No MeSH data available.