Spin Domains in One-Dimensional Conservative Polariton Solitons

Maksym Sich,Alexey V Kavokin,Edmund Clarke,Dmitry V Skryabin,Benjamin Royall,Dmitry N Krizhanovskii,Maurice S Skolnick,Lucy E Tapia-Rodriguez,Helgi Sigurdsson,Evgeny S Sedov,Paul M Walker,Ivan A Shelykh

doi:10.1021/acsphotonics.8b01410

Abstract

We report stable orthogonally polarised domains in high-density polariton solitons propagating in a semiconductor microcavity wire. This effect arises from spin dependent polariton-polariton interactions and pump-induced imbalance of polariton spin populations. The interactions result in an effective magnetic field acting on polariton spin across the soliton profile, leading to the formation of polarisation domains. Our experimental findings are in excellent agreement with theoretical modelling taking into account these effects.

Highlights

T emporal and/or spatial domains of coupled multiple dipoles play a significant role in the properties of various physical systems
Polarization domain formation is governed by modulation instability with the resultant separation of adjacent domains by a domain wall, a topological defect closely linked to soliton formation.[2−4] While scalar nonlinear effects related to solitons[5,6] have been studied extensively, little attention has been given to the spatiotemporal evolution of the polarization degree of freedom in vectorial optical structures
Recently have timelocalized polarization rotations or polarization domain walls been reported for light traveling in nonlinear optical fibers[8] and for dissipative solitons in vertical-cavity surface-emitting lasers.[9]

Summary

■ RESULTS

We performed our experiments on a 3λ/2 microcavity composed of three embedded InGaAs quantum wells (10 nm thick, 4% indium) and GaAs/AlGaAs (85% Al) distributed. For trace 1 very fast precession of the soliton Stokes vector around the “south” pole of the Poincaré sphere is observed during the first 50 ps (bright red trace in Figure 3d) with a period of T ≃ 10 ps, corresponding to an out-of-plane increased effective magnetic field due to the spin-dependent polariton nonlinearity which induces an energy splitting ΔEeff ≃ 130 μeV. The polariton pulse transforms to a soliton doublet at early stages of propagation as in the experiment (Figure 3a) and is characterized by long streaks of constant S1* polarization as shown in Figure 5e,h, again as in the experiment (see Figure 3b) The reason for this effect is that the Ωz component decreases as the polariton intensity decays, becoming small or comparable to the in-plane magnetic field (Ωx, Ωy) around ∼50 ps. The nonlinear pseudomagnetic field leads to the formation of the polarization domain pattern on top of the solitonic total-intensity pattern

■ CONCLUSION

■ ACKNOWLEDGMENTS

■ REFERENCES