Abstract

We propose a fiber coupler consisting of a central ring and four external cores to generate up to ten orbital angular momentum (OAM) modes. Four coherent input lights are launched into the external cores and then coupled into the central ring waveguide to generate OAM modes. By changing the size of the external cores, one can selectively excite a high-order OAM mode. The quality of the generated OAM modes can be enhanced by adjusting the polarization state and the phase of input lights. We show the generation of OAM modes with odd charge numbers of 9 to +9 (i.e., 10 modes totally) with mode purity of >99% using <2mm long fiber. This fiber coupler design can be extended to enable all-fiber spatial-mode (de)multiplexing.

© 2011 Optical Society of America

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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  10. L. Torner, J. P. Torres, and S. Carrasco, Opt. Express 13, 873 (2005).
    [CrossRef] [PubMed]

2011 (1)

2009 (1)

2008 (1)

S. Franke-Arnold, L. Allen, and M. Padgett, Laser Photon. Rev. 2, 299 (2008).
[CrossRef]

2006 (1)

P. Z. Dashti, F. Alhassen, and H. P. Lee, Phys. Rev. Lett. 96, 043604 (2006).
[CrossRef] [PubMed]

2005 (1)

2004 (1)

2002 (1)

G. Molina-Terriza, J. P. Torres, and L. Torner, Phys. Rev. Lett. 88, 013601 (2002).
[CrossRef] [PubMed]

1998 (1)

1992 (1)

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, and J. P. Woerdman, Phys. Rev. A 45, 8185 (1992).
[CrossRef] [PubMed]

Alhassen, F.

P. Z. Dashti, F. Alhassen, and H. P. Lee, Phys. Rev. Lett. 96, 043604 (2006).
[CrossRef] [PubMed]

Allen, L.

S. Franke-Arnold, L. Allen, and M. Padgett, Laser Photon. Rev. 2, 299 (2008).
[CrossRef]

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, and J. P. Woerdman, Phys. Rev. A 45, 8185 (1992).
[CrossRef] [PubMed]

Barnett, S.

Beijersbergen, M. W.

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, and J. P. Woerdman, Phys. Rev. A 45, 8185 (1992).
[CrossRef] [PubMed]

Carrasco, S.

Courtial, J.

Dashti, P. Z.

P. Z. Dashti, F. Alhassen, and H. P. Lee, Phys. Rev. Lett. 96, 043604 (2006).
[CrossRef] [PubMed]

Feng, X.

Franke-Arnold, S.

Gibson, G.

Kristensen, P.

Lee, H. P.

P. Z. Dashti, F. Alhassen, and H. P. Lee, Phys. Rev. Lett. 96, 043604 (2006).
[CrossRef] [PubMed]

Loh, W. H.

McGloin, D.

Molina-Terriza, G.

G. Molina-Terriza, J. P. Torres, and L. Torner, Phys. Rev. Lett. 88, 013601 (2002).
[CrossRef] [PubMed]

Padgett, M.

Padgett, M. J.

Pas’ko, V.

Petrovich, M. N.

Poletti, F.

Ponzo, G. M.

Ramachandran, S.

Richardson, D. J.

Simpson, N. B.

Snyder, Allan

Allan Snyder, Optical Waveguide Theory (1983).

Spreeuw, R. J. C.

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, and J. P. Woerdman, Phys. Rev. A 45, 8185 (1992).
[CrossRef] [PubMed]

Torner, L.

L. Torner, J. P. Torres, and S. Carrasco, Opt. Express 13, 873 (2005).
[CrossRef] [PubMed]

G. Molina-Terriza, J. P. Torres, and L. Torner, Phys. Rev. Lett. 88, 013601 (2002).
[CrossRef] [PubMed]

Torres, J. P.

L. Torner, J. P. Torres, and S. Carrasco, Opt. Express 13, 873 (2005).
[CrossRef] [PubMed]

G. Molina-Terriza, J. P. Torres, and L. Torner, Phys. Rev. Lett. 88, 013601 (2002).
[CrossRef] [PubMed]

Vasnetsov, M.

Woerdman, J. P.

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, and J. P. Woerdman, Phys. Rev. A 45, 8185 (1992).
[CrossRef] [PubMed]

Yan, M. F.

Appl. Opt. (1)

Laser Photon. Rev. (1)

S. Franke-Arnold, L. Allen, and M. Padgett, Laser Photon. Rev. 2, 299 (2008).
[CrossRef]

Opt. Express (3)

Opt. Lett. (1)

Phys. Rev. A (1)

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, and J. P. Woerdman, Phys. Rev. A 45, 8185 (1992).
[CrossRef] [PubMed]

Phys. Rev. Lett. (2)

G. Molina-Terriza, J. P. Torres, and L. Torner, Phys. Rev. Lett. 88, 013601 (2002).
[CrossRef] [PubMed]

P. Z. Dashti, F. Alhassen, and H. P. Lee, Phys. Rev. Lett. 96, 043604 (2006).
[CrossRef] [PubMed]

Other (1)

Allan Snyder, Optical Waveguide Theory (1983).

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Figures (8)

Fig. 1
Fig. 1

Structure of the fiber coupler and the phase and polarization state of the input lights. The horizontal (red) electric field components have a phase difference of ± 90 ° relative to the vertical (blue) components.

Fig. 2
Fig. 2

Effective refractive index of the mode in the cores and the ring. Blue curve, effective refractive index of the fundamental mode in the external cores as a function of the core radius. Red horizontal lines, effective refractive index of the H E n , 1 mode in the central ring.

Fig. 3
Fig. 3

(a)  N eff of the symmetric and asymmetric (even and odd) modes composed of H E 3 , 1 in the ring and H E 1 , 1 in the cores. White arrows illustrate the electric field vector direction. (b) Group velocity difference of asymmetric and symmetric modes Δ β 1 = β asym β sym = 1 / v g , asym 1 / v g , asym .

Fig. 4
Fig. 4

Intensity and phase of the azimuthal components of the generated OAM modes with odd charge numbers of + 1 , 3 , + 5 , 7 , and + 9 in the central ring, respectively.

Fig. 5
Fig. 5

Each column shows the OAM weight spectra of the generated OAM modes in decibels with different charge numbers of n. The top is the spectra of the H E modes, and the bottom is the spectra of the E H modes. The OAM weight determines the purity of the desired generated OAM mode. The purity of each OAM mode is > 0.99 , and the cross talk among these modes is lower than 15 dB .

Fig. 6
Fig. 6

Dependence of OAM generation performance on the offset of external cores. (a) Light power in the external core as a function of the propagation distance for three offsets when n = 1 . (b) Coupling length as a function of the offset ( n = 1 9 , odd numbers).

Fig. 7
Fig. 7

Dependence of OAM generation on the input polarization state. For some charge number with appropriate polarization, the weight could exceed 99% and the extinction ratio could exceed 20 dB (i.e., the generation efficiency is > 0.99 ).

Fig. 8
Fig. 8

Dependence of OAM generation on the input wavelength. The higher order OAM mode is more sensitive to the wavelength change because of the larger waveguide dispersion.

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