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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Spin Transfer and Power Flow at Subwavelength Scales David Haefner U NIVERSITY OF C ENTRAL F LORIDA CREOL, C OLLEGE OF O PTICS AND P HOTONICS

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Mechanical action of light Comet tail points away from the Sun Johannes Kepler: 1609 P. N. Lebedev “Experimental examination of light pressure”, Ann. der Physik, 6, 433 1901 Beth R. “Mechanical Detection and Measurement of the Angular Momentum of Light”, Physical. Rev. 50: 115-125 1936. Quantitative experimental observations Nature, 444, 823, 2006 James C. Maxwell: ( 1873 ) “In a medium in which waves are propagated there is a pressure in the direction normal to the wave…” Linear momentumForcePushAngular momentumTorqueRotation Joshua Tree National Park

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Structuring energy flow with scattering? Scattering redistributes the incident energy Scattering depends on: Wavelength Polarization state Incident angle

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Scattering

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Scattering

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Scattering

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Conservation laws for electromagnetic waves Conservation of energy Conservation of linear momentum Conservation of angular momentum Orbital Spin Angular momentum C. Schwartz, A. Dogariu, Opt. Express 14, 8425-8433 (2006) Scattering

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Virtual location of a source Distance along X axis [λ] Distance along Y axis [λ] Right Circular Left Circular Linear

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Energy flow Complex behavior for larger spheres spans several λ

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Direction sensitive observation Dipole x [μm] z [μm] (IR IL)(IR IL) 4.62μm polystyrene sphere in oil x [μm] z [μm] (IR IL)(IR IL) Single Mode Fiber LeftRightLinear

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Experimental setup Laser Polarizer /2 /4 Coherent fiber bundle CCD Detector Incoherent illumination Typical incoherent image on CCD Micrometer size spheres /4 Sumitomo IGN-08/30 Single mode fiber Fiber scanned 5 microns from surface, NA of fiber = 0.3 532nm light excitation 4.62μm diameter polystyrene sphere in oil

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Experimental results D. Haefner, S. Sukhov, A. Dogariu, Phys. Rev. Lett. 102, 123903 (2009) First demonstration of momentum conservation in scattering First demonstration of spin Hall effect in spherical geometry

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Torques on lossless spheres

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Torques on lossless spheres Spin Torque Orbital Torque Spin Torque

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Counter clockwise Brownian motion Intrinsic absorption D. Haefner, S. Sukhov, A. Dogariu, Phys. Rev. Lett. 103, 173602 (2009) Orbital Torque Spin Torque Clockwise Torques on lossless spheres

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE A new mechanism for momentum exchange Optically induced torques Asymmetry Absorption Birefringence Near-field interaction Angular momentumTorque Linear momentumForcePush Rotation Symmetric Lossless Homogeneous

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Summary Right Left Linear Shift in perceived interaction volume Spin Hall effect of light Angular momentum exchange in scattering D. Haefner, S. Sukhov, A. Dogariu, “Spin Hall Effect of Light in Spherical Geometry”, Phys. Rev. Lett. 102, 123903 (2009)

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Photonic Diagnostics of Random Media UCF College of Optics and Photonics CREOL & FPCE Summary Right Left Linear Shift in perceived interaction volume Spin Hall effect of light Angular momentum exchange in scattering Interaction provides a “new mechanism” for optical torques D. Haefner, S. Sukhov, A. Dogariu, “Conservative and Nonconservative Torques in Optical Binding”, Phys. Rev. Lett. 103, 173602 (2009) Continuous spin and orbital torques Complex dependence on size for directionality of torques D. Haefner, S. Sukhov, A. Dogariu, “Spin Hall Effect of Light in Spherical Geometry”, Phys. Rev. Lett. 102, 123903 (2009)

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