Abstract

We present the experimental realization of transverse mode conversion in an optical fiber via an optically induced long-period grating. The transient gratings are generated by femtosecond laser pulses, exploiting the Kerr effect to translate intensity patterns emerging from multimode interference into a spatial refractive index modulation. Since these modulations exist only while the pump beam is present, they can be used for optical switching of transverse modes. As only a localized part of the grating was written at a time and the probe beam was co-propagating with the pump beam the required pulse energies could be reduced to 120 nJ which is about a factor of 600 lower than in previous quasi-continuous-wave experiments. Accompanying numerical simulations allow a better understanding of the involved effects and show excellent agreement to the experimental results.

© 2014 Optical Society of America

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References

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    [Crossref]
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    [Crossref]
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2014 (1)

2013 (4)

N. Amaya, M. Irfan, G. Zervas, R. Nejabati, D. Simeonidou, J. Sakaguchi, B. J. Puttnam, T. Miyazawa, Y. Awaji, N. Wada, and I. Henning, “Fully-elastic multi-granular network with space / frequency / time switching using multi-core fibres and programmable optical nodes,” Opt. Express 21, 8865–8872 (2013).
[Crossref] [PubMed]

D. J. Richardson, J. M. Fini, and L. E. Nelson, “Space-division multiplexing in optical fibres,” Nat. Photonics 7, 354–362 (2013).
[Crossref]

T. Walbaum and C. Fallnich, “Theoretical analysis of transverse mode conversion using transient long-period gratings induced by ultrashort pulses in optical fibers,” Appl. Phys. B 115, 225–235 (2013).
[Crossref]

T. Hellwig, T. Walbaum, and C. Fallnich, “Optically induced mode conversion in graded-index fibers using ultra-short laser pulses,” Appl. Phys. B 112, 499–505 (2013).
[Crossref]

2012 (2)

2011 (2)

B. J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nat. Photonics 5, 141–148 (2011).

M. Schäferling, N. Andermahr, and C. Fallnich, “Investigations on the wavelength dependence of optically induced long-period Bragg gratings,” Appl. Phys. B 102, 809–817 (2011).
[Crossref]

2010 (1)

1999 (1)

1996 (1)

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

1990 (1)

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

1989 (1)

H. Park and B. Kim, “Intermodal coupler using permanently photoinduced grating in two-mode optical fibre,” Electron. Lett. 25, 797–799 (1989).
[Crossref]

Amaya, N.

Andermahr, N.

M. Schäferling, N. Andermahr, and C. Fallnich, “Investigations on the wavelength dependence of optically induced long-period Bragg gratings,” Appl. Phys. B 102, 809–817 (2011).
[Crossref]

N. Andermahr and C. Fallnich, “Optically induced long-period fiber gratings for guided mode conversion in few-mode fibers,” Opt. Express 18, 4411–4416 (2010).
[Crossref] [PubMed]

Awaji, Y.

Bhatia, V.

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

Bilodeau, F.

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

Bures, J.

J. Bures, Guided Optics (Wiley/VCH, 2009).

Carpenter, J.

Ding, Y.

Duparré, M.

Eggleton, B. J.

B. J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nat. Photonics 5, 141–148 (2011).

Erdogan, T.

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

Fallnich, C.

T. Walbaum and C. Fallnich, “Theoretical analysis of transverse mode conversion using transient long-period gratings induced by ultrashort pulses in optical fibers,” Appl. Phys. B 115, 225–235 (2013).
[Crossref]

T. Hellwig, T. Walbaum, and C. Fallnich, “Optically induced mode conversion in graded-index fibers using ultra-short laser pulses,” Appl. Phys. B 112, 499–505 (2013).
[Crossref]

M. Schäferling, N. Andermahr, and C. Fallnich, “Investigations on the wavelength dependence of optically induced long-period Bragg gratings,” Appl. Phys. B 102, 809–817 (2011).
[Crossref]

N. Andermahr and C. Fallnich, “Optically induced long-period fiber gratings for guided mode conversion in few-mode fibers,” Opt. Express 18, 4411–4416 (2010).
[Crossref] [PubMed]

Fini, J. M.

D. J. Richardson, J. M. Fini, and L. E. Nelson, “Space-division multiplexing in optical fibres,” Nat. Photonics 7, 354–362 (2013).
[Crossref]

Flamm, D.

Forbes, A.

Hellwig, T.

T. Hellwig, T. Walbaum, and C. Fallnich, “Optically induced mode conversion in graded-index fibers using ultra-short laser pulses,” Appl. Phys. B 112, 499–505 (2013).
[Crossref]

Henning, I.

Hill, K.

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

Hirao, K.

Irfan, M.

Johnson, D.

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

Judkins, J.

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

Kazansky, P. G.

Kim, B.

H. Park and B. Kim, “Intermodal coupler using permanently photoinduced grating in two-mode optical fibre,” Electron. Lett. 25, 797–799 (1989).
[Crossref]

Kondo, Y.

Lemaire, P.

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

Luther-Davies, B.

B. J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nat. Photonics 5, 141–148 (2011).

Malo, B.

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

Mitsuyu, T.

Miyazawa, T.

Naidoo, D.

Nejabati, R.

Nelson, L. E.

D. J. Richardson, J. M. Fini, and L. E. Nelson, “Space-division multiplexing in optical fibres,” Nat. Photonics 7, 354–362 (2013).
[Crossref]

Nouchi, K.

Ou, H.

Park, H.

H. Park and B. Kim, “Intermodal coupler using permanently photoinduced grating in two-mode optical fibre,” Electron. Lett. 25, 797–799 (1989).
[Crossref]

Peucheret, C.

Puttnam, B. J.

Richardson, D. J.

D. J. Richardson, J. M. Fini, and L. E. Nelson, “Space-division multiplexing in optical fibres,” Nat. Photonics 7, 354–362 (2013).
[Crossref]

Richardson, K.

B. J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nat. Photonics 5, 141–148 (2011).

Sakaguchi, J.

Schäferling, M.

M. Schäferling, N. Andermahr, and C. Fallnich, “Investigations on the wavelength dependence of optically induced long-period Bragg gratings,” Appl. Phys. B 102, 809–817 (2011).
[Crossref]

Schulze, C.

Simeonidou, D.

Sipe, J.

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

Skinner, I.

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

Thomsen, B. C.

Vengsarkar, A.

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

Vineberg, K.

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

Wada, N.

Walbaum, T.

T. Walbaum and C. Fallnich, “Theoretical analysis of transverse mode conversion using transient long-period gratings induced by ultrashort pulses in optical fibers,” Appl. Phys. B 115, 225–235 (2013).
[Crossref]

T. Hellwig, T. Walbaum, and C. Fallnich, “Optically induced mode conversion in graded-index fibers using ultra-short laser pulses,” Appl. Phys. B 112, 499–505 (2013).
[Crossref]

Watanabe, M.

Wilkinson, T. D.

Xu, J.

Zervas, G.

Appl. Phys. B (3)

T. Walbaum and C. Fallnich, “Theoretical analysis of transverse mode conversion using transient long-period gratings induced by ultrashort pulses in optical fibers,” Appl. Phys. B 115, 225–235 (2013).
[Crossref]

T. Hellwig, T. Walbaum, and C. Fallnich, “Optically induced mode conversion in graded-index fibers using ultra-short laser pulses,” Appl. Phys. B 112, 499–505 (2013).
[Crossref]

M. Schäferling, N. Andermahr, and C. Fallnich, “Investigations on the wavelength dependence of optically induced long-period Bragg gratings,” Appl. Phys. B 102, 809–817 (2011).
[Crossref]

Electron. Lett. (2)

H. Park and B. Kim, “Intermodal coupler using permanently photoinduced grating in two-mode optical fibre,” Electron. Lett. 25, 797–799 (1989).
[Crossref]

K. Hill, B. Malo, K. Vineberg, F. Bilodeau, D. Johnson, and I. Skinner, “Efficient mode conversion in telecommunication fibre using externally written gratings,” Electron. Lett. 26, 1270–1272 (1990).
[Crossref]

J. Lightwave Technol. (2)

A. Vengsarkar, P. Lemaire, J. Judkins, V. Bhatia, T. Erdogan, and J. Sipe, “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14, 58–65 (1996).
[Crossref]

J. Carpenter, B. C. Thomsen, and T. D. Wilkinson, “Degenerate mode-group division multiplexing,” J. Lightwave Technol. 30, 3946–3952 (2012).
[Crossref]

Nat. Photonics (2)

B. J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nat. Photonics 5, 141–148 (2011).

D. J. Richardson, J. M. Fini, and L. E. Nelson, “Space-division multiplexing in optical fibres,” Nat. Photonics 7, 354–362 (2013).
[Crossref]

Opt. Express (3)

Opt. Lett. (2)

Other (1)

J. Bures, Guided Optics (Wiley/VCH, 2009).

Supplementary Material (1)

» Media 1: MP4 (1312 KB)     

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Figures (5)

Fig. 1
Fig. 1 Mode conversion by OLPGs: The intensity distribution of the multi-mode interference (MMI) of a corresponding cw-pump beam equally distributed between the LP01- and the LP02-mode is shown projected to the xz-plane while the change in modal probe energy is shown on the yz-plane, with z being the propagation direction. The probe pulse intensity distributions at the beginning of the fiber and after maximum conversion are shown in the insets as well as the temporal intensity profiles of both probe modes (red = LP01−, blue = LP02− mode). The localized parts of the OLPG induced by a femtosecond pump beam are indicated by the grey rectangles. The conversion speed is exaggerated in this schematic representation. See Media 1 for an animated version of the process.
Fig. 2
Fig. 2 Schematic diagram of the experimental setup (angles and distances are not drawn to scale). PBS: polarizing beam splitter, PD1-PD3: photo diodes, WDG: wedged glass substrate, L1-L3: lenses, MMF: multi-mode fiber, MO: microscope objective, HWP: half-wave plate, Pol: polarizer, SLM: spatial-light modulator, CCD: charged-coupled device camera, PH: pinhole. For further details see text.
Fig. 3
Fig. 3 Measured normalized excited modal contents (orientational degeneracy marked with “e”) in the Passive 25 fiber for the pump and probe beam individually.
Fig. 4
Fig. 4 (a) Probe power measured with PD2 as a function of the phase difference between probe and pump beam in front of the fiber at an average pump beam power of 150 mW and an average probe beam power of 15 mW. The horizontal dashed line indicates the probe power P0 without a pump beam present. The markers indicate phase delays that are investigated in more detail in sub-figure (b): Here, the pump energy dependent difference between the probe power levels “with” and “without” pump beam present is depicted for different phase differences measured with PD1 (dotted lines to guide the eye). For details see the text.
Fig. 5
Fig. 5 Relative modal distribution between LP01− and LP02−mode as a function of the pump and probe pulse energy when the pump beam was blocked (black squares and diamonds) as well as when pump and probe beam overlapped in time (red and blue triangles). The results of a corresponding numerical simulation are presented as the red dashed and the blue dash-dotted curves (for details see text). A good contrast between the probe and the residual pump beam was required for accurate modal content measurements. As the polarization contrast at PBS2 was limited, the probe beam energy (upper x-axis) was therefore always set to 10% of the pump energy (lower x-axis) during the experiment as well as within the simulation to be well above the residual pump beam energy.

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