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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 for combined OAM-MDM and SDM of perfect vortices. OAM values in the range {−3, −2, −1, 0, +1, +2, +3}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the DOE far-field. Marker colours and forms refer to the three different radial channels (inner ring: red circles–central ring: green squares–outer ring: blue triangles). Number of total OAM channels: 21.
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f4: (a) Phase pattern of DOE for combined OAM-MDM and SDM of perfect vortices. OAM values in the range {−3, −2, −1, 0, +1, +2, +3}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the DOE far-field. Marker colours and forms refer to the three different radial channels (inner ring: red circles–central ring: green squares–outer ring: blue triangles). Number of total OAM channels: 21.

Mentions: For the sake of completeness, we show also the case when an increased set of OAM values and both the azimuthal and the radial degrees of freedom are exploited in order to arrange demultiplexed channels in far-field for combined OAM-MDM and SDM. This second DOE pattern is designed in order to have s = 3 and ℓ values in the set {−3, −2, −1, 0, +1, +2, +3}, i.e. n = 7, for a total of 21 OAM channels. In this case, the carrier spatial frequencies were chosen so that the far-field peaks were arranged on three different circles, corresponding to the three different beam sizes, and equally-spaced angular positions (see Fig. 4(a)), as it follows:


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 for combined OAM-MDM and SDM of perfect vortices. OAM values in the range {−3, −2, −1, 0, +1, +2, +3}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the DOE far-field. Marker colours and forms refer to the three different radial channels (inner ring: red circles–central ring: green squares–outer ring: blue triangles). Number of total OAM channels: 21.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: (a) Phase pattern of DOE for combined OAM-MDM and SDM of perfect vortices. OAM values in the range {−3, −2, −1, 0, +1, +2, +3}, 8 phase levels: 0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4. Numerical calculation with custom MATLAB code. (b) Scheme of channels constellation in the DOE far-field. Marker colours and forms refer to the three different radial channels (inner ring: red circles–central ring: green squares–outer ring: blue triangles). Number of total OAM channels: 21.
Mentions: For the sake of completeness, we show also the case when an increased set of OAM values and both the azimuthal and the radial degrees of freedom are exploited in order to arrange demultiplexed channels in far-field for combined OAM-MDM and SDM. This second DOE pattern is designed in order to have s = 3 and ℓ values in the set {−3, −2, −1, 0, +1, +2, +3}, i.e. n = 7, for a total of 21 OAM channels. In this case, the carrier spatial frequencies were chosen so that the far-field peaks were arranged on three different circles, corresponding to the three different beam sizes, and equally-spaced angular positions (see Fig. 4(a)), as it follows:

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