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Quantum Dots in Photonic Structures

Lecture 11: QD- microcavity in strong coupling regime. Quantum Dots in Photonic Structures. Wednesdays , 17.00, SDT. Jan Suffczyński. Projekt Fizyka Plus nr POKL.04.01.02-00-034/11 współfinansowany przez Unię Europejską ze środków Europejskiego

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Quantum Dots in Photonic Structures

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  1. Lecture 11: QD-microcavity in strongcoupling regime Quantum Dots in PhotonicStructures Wednesdays, 17.00, SDT Jan Suffczyński Projekt Fizyka Plus nr POKL.04.01.02-00-034/11 współfinansowany przez Unię Europejską ze środków Europejskiego Funduszu Społecznego w ramach Programu Operacyjnego Kapitał Ludzki

  2. Plan for today Extended Reminder 2. QD-CavityMode in the strongcoupling regime – introduction 3. QD-CavityMode in the strongcoupling regime in Photoluminescence and reflectivity

  3. Qualityfactor of a planarcavity The reflectivity of a DBR consisting of m mirror pairs (n0equals 1 for the top mirror and n0 = nGaAs for thebottom mirror) AlAs/GaAs planar microcavity sample with 20/24 mirror pairs in the upper/lower DBR

  4. From 1D to 3D photoniccrystal Planarmicrocavity= 1D confinement of the light Pillarmicrocavity= 3D confinement of the light DBR made of ZnSSe and MgS/ZnCdSesupperlattices Lohmeyer et al.

  5. Photoluminescence - Micropillareigenmodes Experiment Simulation • Extended transfer matrix method: • Material absorption included • Equal emission intensity of each line assumed T. Jakubczyk et al.

  6. Qualityfactor of the micropillar: losssources Top view Photon Escape  Rate „Planar” losses + „Sidewall” losses ~ + + r dr dr: typically ~ 10 nm Scatteringlosses proportional tothe transverse mode intensityat the microresonatoredge:

  7. Sidewallroughness GaAs/AlAsDBRs Roughness of the order of tens of nm

  8. Purcell factor vs diameter • Pillardiameter D decreases - > V decreases, but also Q decreases • Fp ~ Q/V • Nonmonotnicdependence of Fp on the pillardiameter

  9. Q factoroscillations Oscillationsattributed to a coupling of the fundamentalmode to higher-order pillar modes Basic idea: + +

  10. Decaytimemeasurements XC XC XX XX X X M M XX on resonance with mode XX out of resonance with mode T = 40 K T = 10 K Time Photon Energy

  11. Decay rate as a function of detuning • Strong enhancement of the decay rate at zero-detuning

  12. Directing of the emission • Not onlyacceleration of the emissionthanks to the mode Braggmirrors

  13. Directing of the emission • Not onlyacceleration of the emissionthanks to the mode, but alsodirecting of the emission! Couplingcoefficient to the mode b= FP/(FP+1)

  14. Deterministic QD-CavityModematching

  15. Resist development Nickel mask deposition Etching: Lift-off Pillar with a QD placed in the mode maximum Deterministic QD-CavityModematching Signal Photoresist exposured

  16. GaAs/AlGaAs QD AlGaAs (Al rich region) Substrate GaAs Microdiscmicrocavitiesproductiontechhnology Resistdeposition + Negativeelectrolithography

  17. GaAs/AlGaAs QD AlGaAs (Al rich region) Substrate GaAs Microdiscmicrocavitiesproductiontechhnology Resistdeposition + Negativeelectrolithography Non-selective wet etching

  18. GaAs/AlGaAs QD AlGaAs (Al rich region) Substrate GaAs Microdiscmicrocavitiesproductiontechhnology Resistdeposition + Negativeelectrolithography Non-selective wet etching Selectivewet etching Removing of the resist (acetone)

  19. The idea:

  20. The realization: Reitzenstein et al.

  21. The results: • Temperaturetuning of X energy • Q factor of 13.000 • Electricallypumped

  22. The idea:

  23. Purcell effect in an electrically tunable QD-cavity system The realization: Laucht et al., 2009

  24. Purcell effect in an electrically tunable QD-cavity system The results: Purcell effect in an electrically tunable QD-cavity system Laucht et al., 2009

  25. QD- CavityMode in the strongcouplingregime

  26. Light-matterinteraction: Strongcoupling Energy S1 S2 CavityMode Emitter Optical Modes outside the cavity When S1> S2 and Emitter in resonance with the CavityMode: Photonpreserved in the cavity „for long” Reabsorption and reemission of the photon by the mitter

  27. Strongcoupling –Rabisplitting Out of the resonence: |1,0> : Emptycavity Excited emitter

  28. Strongcoupling –Rabisplitting Out of the resonence: |1,0> : Emptycavity Excited emitter |0,1> : Photon insidecavity Emitter in groundstate

  29. In resonance: Energy Rabbi SplittingDR (|0,1>|1,0>)/ (|0,1>+|1,0>)/ Eigenstates : Entengledstatesemitter-photon 2 2 ↔ |0,1> |1,0> Oscillations with Rabifrequency = R / h Strongcoupling –Rabisplitting Out of the resonence: |1,0> : Emptycavity Excited emitter |0,1> : Photon insidecavity Emitter in groundstate

  30. Weak vs strongcoupling Out of the cavity

  31. Weak vs strongcoupling Out of the cavity

  32. Conditions for the strongcoupling regime Decisivefactors: QD ~ 1/τQD Emitterdecayrate: C ~ 1/τC Cavitydecayrate: Couplingconstant QD-Cavitymode:

  33. Conditions for the strongcoupling regime Decisivefactors: QD ~ 1/τQD Emitterdecayrate: C ~ 1/τC Cavitydecayrate: Couplingconstant QD-Cavitymode: g>M/2, QD Condition for the strongcoupling: Rabisplitting On QD-Cavityresonance:

  34. Strongcoupling regime Energylevels versus detuning: QD– Cavitymodedetuning • At resonanceQD- Cavitymode: anticrossingof the levels! Rabisplitting:

  35. Conditions of the strongcoupling Rabisplitting: • Desired: • Large g, thus small V and largeoscillatorstrengthf • Small M, this high Qualityfactor of the Cavity Q Q=

  36. Weakcoupling vs strongcoupling Anticrossing/ no anticrossing Reithmaieret al., Nature (2004)

  37. Weakcoupling vs strongcoupling Exchange of linewidths/ no lw exchange Reithmaieret al., Nature (2004)

  38. Weakcoupling vs strongcoupling Anticrossing/ no anticrossing Exchange of linewidths/ no lw exchange Equalintensityatresonance/ X intensityincreasedatresonance Reithmaieret al., Nature (2004)

  39. QD-Cavitystrongcoupling : beginnings Strong coupling in a single quantum dot–semiconductor microcavity system Vacuum Rabi splitting with asingle quantum dot in aphotoniccrystalnanocavity Exciton-Photon Strong-Coupling Regime for a Single Quantum Dot Embedded in a Microcavity E. Peter et al., Phys. Rev. Lett. (2005) Reithmaieret al., Nature (2004) T. Yoshie et al., Nature (2004)

  40. QD-Cavitystrongcoupling : beginnings V=0.04µm3 V=0.07 µm3 V=0.3 µm3 InAs : f = 10 In0.6Ga0.4As : f = 50 GaAs : f=100

  41. Etat de l’art : Couplage fort pour une boîte quantique unique en cavité V=0.04µm3 V=0.07 µm3 V=0.3 µm3 InAs : f = 10 In0.6Ga0.4As : f = 50 GaAs : f=100

  42. 32layers 36 layers Strongcoupling in micropillars with anelliptic cross-section Qualityfactor vs diameter + improvedetching  Higher Q factor of the micropillars

  43. Strongcoupling in micropillars with anelliptic cross-section 37K X Qa = 22500 DRa = 35 meV Ma 36K Mb Intensity (arb.units) DRb = 32 meV Qb = 15500 35K Temperature (K) Ma Mb  AnticrossingX – Mode, Rabi= 35 eV 34K X 1323.8 1324 1324.2 Energy (meV) • (A. Dousse, JS et al., 2008)

  44. QD-cavitystrongcouplingevidenced in reflectivity Reflectivity with use of finelytunable laser

  45. QD-cavitystrongcouplingevidenced in reflectivity • Very high spectral resolution • Resonantexcitation Loo et al., 2012

  46. ElectricallycontrolledstrongcouplingQD-cavitymode • No need of temperaturetuning • Rabisplitting of 121μeV Laucht et al., 2009

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