Orbital Angular Momentum of Light and its control with

metamaterials/metasurfaces

Min Ku KimNov 27, 2017

ECE 695 Presentation

Table of Contents

1. Introduction.

2. What is Orbital Angular Momentum of light?

3. Examples of OAM in applications.

Why ECE695?

Xu et al., Science 347(6218), 154-159 (2015).Kim et al., Nature Materials 9, 929-937 (2010).

-Stretchable, Flexible, high performance single crystalline silicon/metals.

3D nano-structures LED Au nano-features

Why ECE695?

Meinzer et al., Nature Photonics 8, 889-898 (2014).

- Metamaterials/metasurfaces geometry dependent.

Why ECE695?

Image: Resonance Science Foundation

TransientOptics?

Table of Contents

1. Introduction.

2. What is Orbital Angular Momentum of light?

3. Examples of OAM in applications.

What is Orbital Angular Momentum?

Brief history

- John Henry Poynting already postulated in 1909, Proceedings of the Royal Society of London

Image: WikipediaJ.H. Poynting, Proc. R. Soc. Lond. A 1909 82 560-567.

What is Orbital Angular Momentum?

Mathematics of OAM

- The mathematics of OAM was presented by L. Allen and J.P. Woerman, Leiden University, Netherlands.

- Laguerre-Gauss mode representation contains integers:- l=nr (helical twist along a wavelength), p=nr (radial nodes)

Allen et al., Phys. Rev. A 45, 8185 (1992).

What is Orbital Angular Momentum?

Total EM field angular momentum JEM.

van Enk and Nienhuis, Optics Communication 94 (1992) 147-158.

- First part, spin angular momentum (SAM) >> Wave Polarization- Second part, orbital angular momentum (OAM)

- In photons, polarization is limited to 2 spin states but it can have multiple OAM eigenstates.

- Represents new optical degree of freedom of light.- Higher order mode, more information transmission.

What is Orbital Angular Momentum?

Padgett et al., Physics Today 57, 5, 35 (2004).

Phase Front Annular Intensity Phase

- Unlike SAM, OAM is independent of

beam polarization.

- Poynting vector (Green Arrow) not

parallel to the beam axis. Follows spiral

trajectory around the axis.

- Helical wavefronts have simple ring

shape intensity.

- Interference with a plane produces

spiral intensity pattern.

- Number of spiral arms equals the

number of l.

What is Orbital Angular Momentum?

Analogy to something bigger.

Image: NASA

What is Orbital Angular Momentum?

Analogy to something bigger, New perspective.

Image: Youtube

Table of Contents

1. Introduction.

2. What is Orbital Angular Momentum of light?

3. Examples of OAM in applications.

Generating OAM via plasmonic metasurface

Karimi et al., Light:Science & Application (2014) 3, e167.

- Array Gold nano-antennas on glass. Each element exhibits half-wavelength optical retardation

between two orthogonal linear polarizations. Circular array posses transverse topological charge q=1

- Metasurface is rotationally invariant, does not exchange angular momentum with optical field.

- Helicity still changes, by conservation of momentum, beam should rotate about propagation axis.

- Circularly polarized beams, ΔSZ is ±2ħ -> OAM of l = ±2.

Gold Antennas of indium tin oxide coated glass

Generating OAM via plasmonic metasurface

- Experiment with circularly polarized light 780nm. Converted part of beam isolated using quarter-

wave plate and polarizer, different from unconverted beam.

- Intensity shows preservation of doughnut shape. -> existence of optical vortex at origin.

- Interference patterns between spherical wave shows converted beam OAM order of 2.

Intensity

Karimi et al., Light:Science & Application (2014) 3, e167.

“Spin-enabled” metasurfaces.

Li et al., Nano Lett. 2013, 13, 4148-4151.

R-circular polarized

Y-directionpolarized

- Z-shaped etched on gold surface. b=200nm, w=50nm, g=65, d=300nm.

- Metasurface of topological charge q = 1. Flips the spin.

- Similar resultant of OAM.

Generation of OAM using dielectric metamaterial

Vertically emitting ring quantum cascade laser

Dielectric Material on back side

- Refractive index gradient (different size subwavelength holes) fabricated directly on the back side.

- This method allows easier on-chip integration and 2D array integration.

Szedlak et al., in Conference on Lasers and Electro-Optics, OSA Technical Digest (online) (Optical Society of America, 2016), paper ATh1J.6.

Generation of OAM using dielectric metamaterial

Vertically emitting ring quantum cascade laser

Dielectric Material on back side

- Metamaterial induced OAM beams with central intensity maximum.

- Superposition of two beams shows spiral interference pattern.

- Method can be applied to vertically emitting semiconductor laser.

No OAM OAM l=1

Superposition

Szedlak et al., in Conference on Lasers and Electro-Optics, OSA Technical Digest (online) (Optical Society of America, 2016), paper ATh1J.6.

Thankyou.

References1. S. Xu, Z. Yan, K.-I. Jang, W. Huang, H. Fu, J. Kim, Z. Wei, M. Flavin, J. McCracken, R. Wang, A. Badea, Y. Liu, D. Xiao, G. Zhou, J. Lee, H.U. Chung, H. Cheng,

W. Ren, A. Banks, X. Li, U. Paik, R.G. Nuzzo, Y. Huang, Y. Zhang and J.A. Rogers, "Assembly of Micro/nanomaterials into Complex, Three-Dimensional Architectures by Compressive Buckling," Science 347(6218), 154-159 (2015).

2. R.-H. Kim, D.-H. Kim, J. Xiao, B.H. Kim, S.-I. Park, B. Panilaitis, R. Ghaffari, J. Yao, M. Li, Z. Liu, V. Malyarchuk, D.G. Kim, A.-P. Le, R.G. Nuzzo, D.L. Kaplan, F.G. Omenetto, Y. Huang, Z. Kang and J.A. Rogers, “Waterproof AlInGaP Optoelectronics on Stretchable Substrates with Applications in Biomedicine and Robotics,” Nature Materials 9, 929-937 (2010).

3. N. Meinzer, W.Barnes and I.Hopper, “Plasmonic meta-atoms and merasurfaces,” Nature Photonics 8, 889-898 (2014).4. J.H. Poynting, “The wave motion of revolving shaft, and a suggestion as to the angular momentum in a beam of circularly polarized light”, Proc. R. Soc. Lond. A

1909 82 560-567.5. L. Allen, M.W. Beijersbergen, R.J.C. Spreeuw, and J.P. Woerdman, “Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser

modes”, Phys. Rev. A 45, 8185 (1992).6. S.J. van Enk and G. Nienhuis, “Eigenfunction description of laser beams and orbital angular momentum of light”, Optics Communication 94 (1992) 147-158.7. M.Padgett, J.Courtial and L. Allen, “Light’s Orbital Angular Momentum”, Physics Today 57, 5, 35 (2004).8. E. Karimi, S. Schulz, I. De Leon, H. Qassim, J. Upham, and R. Boyd, “Generating optical orbital angular momentum at visible wavelength using a plasmonic

metasurface”, Light:Science&Application (2014) 3, e167.9. G. Li, M. Kang, S. Chen, S. Zhang, E. Pun, K.W. Cheah, and J. Li, “Spin-Enabled Plasmonic Metasurface for Manipulating Orbital Angular Momentum of Light”,

Nano Lett. 2013, 13, 4148-4151.10. R. Szedlak, T. Hisch, M. Holzbauer, D. MacFarland, T. Zederbauer, H. Detz, A. M. Andrews, W. Schrenk, S. Rotter, and G. Strasser, "On-chip Generation of

Infrared Orbital Angular Momentum Beams using a Dielectric Metamaterial," in Conference on Lasers and Electro-Optics, OSA Technical Digest (online) (Optical Society of America, 2016), paper ATh1J.6.