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High-Q small-V Photonic-Crystal Microcavities control of light

High-Q small-V Photonic-Crystal Microcavities control of light. Kirill Atlasov Ecole Polytechnique Fédérale de Lausanne (EPFL) Laboratory of Physics of Nanostructures Lausanne, Switzerland. 2. Control of light: in Nature. Purposes: calculus, communication, data storage.

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High-Q small-V Photonic-Crystal Microcavities control of light

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  1. High-Q small-V Photonic-Crystal Microcavities control of light Kirill Atlasov Ecole Polytechnique Fédérale de Lausanne (EPFL) Laboratory of Physics of Nanostructures Lausanne, Switzerland

  2. 2 Control of light: in Nature

  3. Purposes:calculus, communication, data storage Manipulation: create, select spectrally, guide, interact, (store), detect In a predefined way. 3 Control of Light. Us. courtesy MIT (http://ab-initio.mit.edu/photons)

  4. modify broad-band source (QWR) "speed up" atom-like source (QD) Hennessy, et al, Nature 445, 896, (2007) 4 Microcavities: Control of Light What to control ? • They can be used as coupling blocks and filters in photonic circuits • Control of Spontaneous Emission of a light source

  5. 5 Purcell effect Vahala, Nature, 424, 839, (2003) emitter decays by interaction with continuum rate ~ density of states per volume V DoScavity> DoSfree (resonantly) rate ~ DoS per volume V • fast decay rate of emitter • spont. em. directed into mode

  6. modify broad-band source (QWR) 4 Microcavities: Control of Light What to control ? • They can be used as coupling blocks and filters in photonic circuits • Control of Spontaneous Emission of a light source "speed up" atom-like source (QD) Hennessy, et al, Nature 445, 896, (2007)

  7. 6 Cavity Figure of merit: Q V So, the figure of merit is about Q and V What is it good for?

  8. Indistinguishable photons (identical wave packets for linear-optical quantum computation) Santori et al, Nature, 419, 594, (2002) LED exhibiting laser-like performance (β - spontaneous emission Into cavity mode) LASER (β - spontaneous emission Into lasing mode – low threshold) Yablonovitch in Confined electrons and photons: New physics and applications, (Burstein, Weisbuch, eds) vol. 340 NATO ASI ser.B. Plenum Press (1995) Few QD laser: Strauf et al, PRL 96, 127404, (2006) Strong coupling regime (transfer of energy between oscillators) Khitrova et al, Nat. Phys. 2, 81, (2006) 7 Cavity Figure of merit: Q/V. What is it good for?

  9. 8 Photonic-crystal Microcavities In principle, any defect of the periodicity. John, PRL 58, 2486, (1987) Most practical – membrane PhC

  10. 9 How does it compare to other possibilities? Srinivasan et al, APL 424, 839, (2003) Vahala, Nature 424, 839, (2003) In PhCV < (λ/n)3 Noda et al, Nature 425, 944 (2003) Park et al, Science 305, 1444, (2004)

  11. Few-QD laser Strauf et al, PRL 96, 127404, (2006) β = 0.85 10 Interesting examples: LASERs Electrical pumping QW PhC laser Park et al, Science 305, 1444, (2004) β = 0.25

  12. Two-photon interference (QD in PhC) Laurent et al, APL 87, 163107, (2005) Probability that two colliding photons at beamsplitter exit via two diferent ports is low (given directly by correlation) 11 Interesting examples: Indistinguishable photons Two-photon interference (QD in micropillar) Santori et al, Nature 419, 594, (2002) If 2 indistinguishable photos collide at the beamsplitter they exit via the same port!! => 2-photon inteference Hong et al, PRL 59, 2044, (1987) Cannot arive then at different detectors at the same time

  13. (transfer of energy between oscillators) Strong coupling (photons here) 2 1 decay κ decay γ If coupling strength between two same-energy oscillators exceeds the mean of their decay rates, the coupled system has two energies – their states split Khitrova et al, Nat. Phys. 2, 81, (2006) 12 Interesting feature: Strong Light-matter Coupling

  14. And the coupling strength (vacuum field fluctuations per volume) transition from Purcell enhancement to Rabi splitting 13 Interesting feature: Strong Light-matter Coupling The decay rate (of photon) ~ 1/Q Wanted: • high Q • small mode volume V Khitrova et al, Nat. Phys. 2, 81, (2006)

  15. Rabi splitting at around zero detuning 14 Interesting feature: Strong Light-matter Coupling 1 QD in PhC Yoshie et al, Nature 432, 200, (2004) Q = 16000 – 20000 When tuned, anticrossing behavior

  16. Two different waveguides... WG 2 stretched... Bandgap -> transmission... Photons with specific energies can exist only in the WG 2 FT if Two mirrors FT of Gaussian envelope In real space 15 Very high-Q: Cavity geometry optimization. Q = 600 000. Akahane et al, Nat. Mater 4, 208, (2005)

  17. normalized frequency f (c/a) |Ex| k-space Qfrom 1500 goes upto >100 000 ky (2π/a) 0 -1 0 1 kx (2π/a) 16 High Q: cavity termination adjustments. Polarization even odd Ey Ex Intensity (arb units) K.F Karlsson, K.A. Atlasov unpublished

  18. high Q small V Strong coupling 2 1 SUMMARY

  19. end

  20. additional stuff

  21. For non-lasing devices β>0.9 have been estimated (0.97) (Kress et al, PRB, 71, 241304, (2005)

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