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Control of spontaneous emission of QD using photonic crystals

Control of spontaneous emission of QD using photonic crystals. Radiative transition -> Spontaneous emission All light sources except lasers. +. excited emitter . environment. Radiative transition -> Spontaneous emission All light sources except lasers.

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Control of spontaneous emission of QD using photonic crystals

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  1. Control of spontaneous emission of QD using photonic crystals Guillaume TAREL, PhC Course, QD EMISSION

  2. Radiative transition -> Spontaneous emission All light sources except lasers + excited emitter environment Guillaume TAREL, PhC Course, QD EMISSION

  3. Radiative transition -> Spontaneous emission All light sources except lasers Excited emitter -> emission of a photon after a characteristic lifetime t + = excited emitter environment Guillaume TAREL, PhC Course, QD EMISSION

  4. A lot of interest in modifying spontaneous emission • Faster emission: Integrated photonics, high speed light sources • Single photon sources: Quantum optics, Quantum criptography • Better emission coupling factor b Guillaume TAREL, PhC Course, QD EMISSION

  5. Emitter : dimensionality of structures Spatial Variations of band edge for carriers (e and h) Baier M., PhD Thesis, 2005 Guillaume TAREL, PhC Course, QD EMISSION

  6. Quantum dot: 3D confinment atomic like emitter Easy incorporation in devices Control Spontaneous emission (SE) Nanopyramids of Gallium Arsenide Low extraction efficiency: Absorption+reflected part+ even total intern reflection Guillaume TAREL, PhC Course, QD EMISSION

  7. + Environment ? « By intentionnaly placing boundaries close to a radiative system, one realize new situations in which excited state decay can be either supressed, greatly enhanced, or even made reversible .» S. Haroche, 1990, Fundamental systems in Quantum Optics -> Cavity Quantum Electrodynamic Guillaume TAREL, PhC Course, QD EMISSION

  8. Weak coupling Cavity decay rate > QD cavity coupling strength SE rate calculated from fermi golden rule… F. Krauss Science 20 May 2005: 1122-1123 Guillaume TAREL, PhC Course, QD EMISSION

  9. mode volumes and Q factor See e.g. Andreani et Al., Physica status solidi. B. -> on-resonance enhanced of resonance supressed Guillaume TAREL, PhC Course, QD EMISSION

  10. Purcell effect Vahala, Nature 2003 E.M.Purcell Phys. Rev. 69 (1946) p. 681 Excited emitter -> emission of a photon after a characteristic lifetime Purcell effect reduces spontaneous emission lifetime Properties of the emitter modified but not fundamentally altered : weak coupling -> Tailoring spontaneous emission Guillaume TAREL, PhC Course, QD EMISSION

  11. Low dimensionality structures Photons confined by modulation of the refractive index: planar microcavity, photonic wires, micropillars, microdisks… Vahala, Nature 2003 Guillaume TAREL, PhC Course, QD EMISSION

  12. Photonic crystals Andreani et Al., Physica status solidi. B. Guillaume TAREL, PhC Course, QD EMISSION

  13. QD+Photonic crystals Both electrons and photons are confined in all dimensions + + Guillaume TAREL, PhC Course, QD EMISSION

  14. Need small mode volumes Vahala Nature 424, 839-846 (2003) M0 and M1 cavitys High Q – Small V Guillaume TAREL, PhC Course, QD EMISSION

  15. Designs concepts holes position and size Phys. Rev. Lett. 95, 013904 (2005) Strauf et Al., Phys. Rev. Lett. 96, 127404 (2006) Guillaume TAREL, PhC Course, QD EMISSION

  16. Yoshie et al., Nature 432, 200-203 Guillaume TAREL, PhC Course, QD EMISSION

  17. Andreani et Al., Physica status solidi. B. Guillaume TAREL, PhC Course, QD EMISSION

  18. Phys. Rev. Lett. 95, 013904 (2005) Spectral + Spatial positioning What is done: 1/ fabrication of structures : emitter embedded in photonic crystal 2/ try to find an emitter coupled to a cavity mode Guillaume TAREL, PhC Course, QD EMISSION

  19. First example H1 PC cavity Pronounced CQED effect r/a r: hole radius Phys. Rev. B 71, 241304 (2005): Kress et al. Guillaume TAREL, PhC Course, QD EMISSION

  20. First example H1 PC cavity Deeper shift in the bandgap Phys. Rev. B 71, 241304 (2005): Kress et al. Guillaume TAREL, PhC Course, QD EMISSION

  21. H1 PC cavity Shortening of emission lifetime of around 5.6 Maximum enhancement around 20 Max(photon lifetime) 2ps Typical QD SE time 1 ns Phys. Rev. B 71, 241304 (2005): Kress et al. Guillaume TAREL, PhC Course, QD EMISSION

  22. H1 PC cavity Shortening AND lengthening Unpaterned membrane Phys. Rev. B 71, 241304 (2005): Kress et al. Guillaume TAREL, PhC Course, QD EMISSION

  23. 2nd example Hexagonal defect microcavity H2 (7 missing holes, triangular lattice, filling factor 40%) 4 of the defect modes of a H2 cavity High power no resolution of QD individual emission Ground state transition of the dots (170) Pump rate limited Phys. Rev. B 66, 041303 (2002): Happ et al. Guillaume TAREL, PhC Course, QD EMISSION

  24. Hexagonal defect microcavity H2 Mode peaks emerge from the spectra Lifetime limited, difference off/on resonance Phys. Rev. B 66, 041303 (2002): Happ et al. Guillaume TAREL, PhC Course, QD EMISSION

  25. on/off resonance *9 SE rate enhancement due to purcell effect Phys. Rev. B 66, 041303 (2002): Happ et al. Guillaume TAREL, PhC Course, QD EMISSION

  26. Phys. Rev. Lett. 95, 013904 (2005) What is done: 1/ fabrication of structures : emitter embedded in photonic crystal 2/ try to find an emitter coupled spectraly and spatially to a cavity mode Guillaume TAREL, PhC Course, QD EMISSION

  27. One more step: « deterministic coupling» Light-matter coupling is no more due to chance Badolato et al., Science 20 May 2005: 1158 - 1161 Guillaume TAREL, PhC Course, QD EMISSION

  28. Positionning of the QD Electric field intensity from FDTD calculations Writing of the S1 PhC SPATIAL COUPLING Trace of the stacked QDs -> high Q cavity mode resonance QD transition energy BUT remains red shifted = approximate SPECTRAL COUPLING Guillaume TAREL, PhC Course, QD EMISSION

  29. Spectral tuning of the mode resonance Enlarge PC holes and thin PC membrane QD emission intensity is modified 5 etching cycles 3 etching cycles Enhancement of radiative decay rate of around 5 Guillaume TAREL, PhC Course, QD EMISSION

  30. CONCLUSION Photonic crystals = tailoring of spontaneous emission using Purcell effect Cavity decay rate > QD cavity coupling strength = Purcell effect Modify spontaneous emission Other really interesting aspects : Cavity decay rate < QD cavity coupling strength Strong coupling Vahala, Nature 2003 Guillaume TAREL, PhC Course, QD EMISSION

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