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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

Phase-only DOE for OAM-MDM in the range {−2, −1, 0, +1, +2}, according to the scheme in Fig. 2.Total intensities in all detector regions for perfect vortex input modes, for the experimental data shown in Fig. 8. For each channel, the detection regions have the same size and are chosen so that they cover the intensity peak area. Intensities are normalized to the total collected energy.
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f9: Phase-only DOE for OAM-MDM in the range {−2, −1, 0, +1, +2}, according to the scheme in Fig. 2.Total intensities in all detector regions for perfect vortex input modes, for the experimental data shown in Fig. 8. For each channel, the detection regions have the same size and are chosen so that they cover the intensity peak area. Intensities are normalized to the total collected energy.

Mentions: Depending on the designed phase pattern, the final output consists of an array of spots, whose brightness is proportional to the corresponding OAM contribution to the input beam. For each input OAM signal, energy is collected in far-field over a well-defined matrix of detectors by measuring light intensity at specific points on the CCD image, in correspondence of the different diffraction orders specified by equation (6). In Fig. 8 normalized intensities are reported for a DOE performing OAM-MDM in the range {−2, −1, 0, +1, +2}. The plot exhibits a well-defined channel response, with efficiencies between 77% and 86% (Fig. 9). The cross-talk XT of the channel corresponding to a selected value ℓ = ℓ* is defined as:


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)

Phase-only DOE for OAM-MDM in the range {−2, −1, 0, +1, +2}, according to the scheme in Fig. 2.Total intensities in all detector regions for perfect vortex input modes, for the experimental data shown in Fig. 8. For each channel, the detection regions have the same size and are chosen so that they cover the intensity peak area. Intensities are normalized to the total collected energy.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f9: Phase-only DOE for OAM-MDM in the range {−2, −1, 0, +1, +2}, according to the scheme in Fig. 2.Total intensities in all detector regions for perfect vortex input modes, for the experimental data shown in Fig. 8. For each channel, the detection regions have the same size and are chosen so that they cover the intensity peak area. Intensities are normalized to the total collected energy.
Mentions: Depending on the designed phase pattern, the final output consists of an array of spots, whose brightness is proportional to the corresponding OAM contribution to the input beam. For each input OAM signal, energy is collected in far-field over a well-defined matrix of detectors by measuring light intensity at specific points on the CCD image, in correspondence of the different diffraction orders specified by equation (6). In Fig. 8 normalized intensities are reported for a DOE performing OAM-MDM in the range {−2, −1, 0, +1, +2}. The plot exhibits a well-defined channel response, with efficiencies between 77% and 86% (Fig. 9). The cross-talk XT of the channel corresponding to a selected value ℓ = ℓ* is defined as:

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