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Diffractive optics for combined spatial- and mode- division demultiplexing of optical vortices: design, fabrication and optical characterization.

Ruffato G, Massari M, Romanato F - Sci Rep (2016)

Bottom Line: During the last decade, the orbital angular momentum (OAM) of light has attracted growing interest as a new degree of freedom for signal channel multiplexing in order to increase the information transmission capacity in today's optical networks.Here we present the design, fabrication and characterization of phase-only diffractive optical elements (DOE) performing mode-division (de)multiplexing (MDM) and spatial-division (de)multiplexing (SDM) at the same time.These novel DOE designs appear promising for telecom applications both in free-space and in multi-core fibers propagation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy 'G. Galilei', University of Padova, via Marzolo 8, 35131 Padova, Italy.

ABSTRACT
During the last decade, the orbital angular momentum (OAM) of light has attracted growing interest as a new degree of freedom for signal channel multiplexing in order to increase the information transmission capacity in today's optical networks. Here we present the design, fabrication and characterization of phase-only diffractive optical elements (DOE) performing mode-division (de)multiplexing (MDM) and spatial-division (de)multiplexing (SDM) at the same time. Samples have been fabricated with high-resolution electron-beam lithography patterning a polymethylmethacrylate (PMMA) resist layer spun over a glass substrate. Different DOE designs are presented for the sorting of optical vortices differing in either OAM content or beam size in the optical regime, with different steering geometries in far-field. These novel DOE designs appear promising for telecom applications both in free-space and in multi-core fibers propagation.

No MeSH data available.


Related in: MedlinePlus

(a) Phase pattern of DOE performing OAM-MDM of optical vortices in the range {−2, −1, 0, +1, +2}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Inner ring: 300 μm, outer ring 500 μm. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the far-field.
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f2: (a) Phase pattern of DOE performing OAM-MDM of optical vortices in the range {−2, −1, 0, +1, +2}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Inner ring: 300 μm, outer ring 500 μm. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the far-field.

Mentions: For the demultiplexing of perfect vortices, it is sufficient to consider only the phase-pattern zone where the incident field is non-. Figure 2(a) exhibits the calculated phase pattern for the sorting of perfect vortices with OAM values in the range {−2, −1, 0, +1, +2} and electromagnetic field confined within a ring with inner and outer radii respectively of 350 μm and 500 μm. At the back-focal plane of a lens with focal length f, the signal spots are located along a circle with radius r = βf/k and equally-spaced angular positions with a step of 2π/5, being k = 2π/λ the wavevector in air. With such a choice, we prevent any channel from overlapping with the zero-order term, which is usually a noise carrier because of unavoidable defects in sample fabrication.


Diffractive optics for combined spatial- and mode- division demultiplexing of optical vortices: design, fabrication and optical characterization.

Ruffato G, Massari M, Romanato F - Sci Rep (2016)

(a) Phase pattern of DOE performing OAM-MDM of optical vortices in the range {−2, −1, 0, +1, +2}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Inner ring: 300 μm, outer ring 500 μm. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the far-field.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837364&req=5

f2: (a) Phase pattern of DOE performing OAM-MDM of optical vortices in the range {−2, −1, 0, +1, +2}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Inner ring: 300 μm, outer ring 500 μm. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the far-field.
Mentions: For the demultiplexing of perfect vortices, it is sufficient to consider only the phase-pattern zone where the incident field is non-. Figure 2(a) exhibits the calculated phase pattern for the sorting of perfect vortices with OAM values in the range {−2, −1, 0, +1, +2} and electromagnetic field confined within a ring with inner and outer radii respectively of 350 μm and 500 μm. At the back-focal plane of a lens with focal length f, the signal spots are located along a circle with radius r = βf/k and equally-spaced angular positions with a step of 2π/5, being k = 2π/λ the wavevector in air. With such a choice, we prevent any channel from overlapping with the zero-order term, which is usually a noise carrier because of unavoidable defects in sample fabrication.

Bottom Line: During the last decade, the orbital angular momentum (OAM) of light has attracted growing interest as a new degree of freedom for signal channel multiplexing in order to increase the information transmission capacity in today's optical networks.Here we present the design, fabrication and characterization of phase-only diffractive optical elements (DOE) performing mode-division (de)multiplexing (MDM) and spatial-division (de)multiplexing (SDM) at the same time.These novel DOE designs appear promising for telecom applications both in free-space and in multi-core fibers propagation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy 'G. Galilei', University of Padova, via Marzolo 8, 35131 Padova, Italy.

ABSTRACT
During the last decade, the orbital angular momentum (OAM) of light has attracted growing interest as a new degree of freedom for signal channel multiplexing in order to increase the information transmission capacity in today's optical networks. Here we present the design, fabrication and characterization of phase-only diffractive optical elements (DOE) performing mode-division (de)multiplexing (MDM) and spatial-division (de)multiplexing (SDM) at the same time. Samples have been fabricated with high-resolution electron-beam lithography patterning a polymethylmethacrylate (PMMA) resist layer spun over a glass substrate. Different DOE designs are presented for the sorting of optical vortices differing in either OAM content or beam size in the optical regime, with different steering geometries in far-field. These novel DOE designs appear promising for telecom applications both in free-space and in multi-core fibers propagation.

No MeSH data available.


Related in: MedlinePlus