Analysis of a segmented q-plate tunable retarder for the generation of first-order vector beams

Davis, Jeffrey A.; Hashimoto, Nobuyuki; Kurihara, Makoto; Hurtado, Enrique; Pierce, Melanie; Sánchez-López, Marı́a del Mar; Badham, Katherine

doi:10.1364/ao.54.009583

Cited by 41 publications

(30 citation statements)

References 33 publications

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“…As a result, we generate the 36 vector beams, generated with encoded q -plate devices with values q = ± 1/2, q = ± 1, and q = ± 3/2 (along orders diffracted horizontally), each one as illuminated with the six input cardinal polarizations (along orders diffracted vertically). Note that a given q -plate generates different output vector beams of the same charge for different input polarizations 25 .…”

Section: Results: Building a Multiple Vector Beam Generatormentioning

confidence: 99%

“…Q-plates can be fabricated with structured metamaterials 22 (then also named as s -plates), with elements based on geometric phase holograms 23 , or with liquid-crystal materials 24, 25 , these last showing the possibility to tune the retardance and be operative at different wavelengths. Alternatively, they can be encoded using spatial light modulators (SLM) 26, 27 .…”

Section: Introductionmentioning

confidence: 99%

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Vector Beam Polarization State Spectrum Analyzer

Moreno

Davis

Badham

et al. 2017

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We present a proof of concept for a vector beam polarization state spectrum analyzer based on the combination of a polarization diffraction grating (PDG) and an encoded harmonic q-plate grating (QPG). As a result, a two-dimensional polarization diffraction grating is formed that generates six different q-plate channels with topological charges from −3 to +3 in the horizontal direction, and each is split in the vertical direction into the six polarization channels at the cardinal points of the corresponding higher-order Poincaré sphere. Consequently, 36 different channels are generated in parallel. This special polarization diffractive element is experimentally demonstrated using a single phase-only spatial light modulator in a reflective optical architecture. Finally, we show that this system can be used as a vector beam polarization state spectrum analyzer, where both the topological charge and the state of polarization of an input vector beam can be simultaneously determined in a single experiment. We expect that these results would be useful for applications in optical communications.

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Section: Results: Building a Multiple Vector Beam Generatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vector Beam Polarization State Spectrum Analyzer

Moreno

Davis

Badham

et al. 2017

Sci Rep

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“…High speed and high-frequency switching and modulation of a conventional communication optical channel can be achieved by tunable liquid crystal retarders 18, 19 or via electro-optical effects in active integrated optical-based devices 20 . In the integrated optical devices, phase, amplitude, and polarization of the electric field of the optical communication signal are modulated using miniaturized waveguides with straight or interferometric configurations 21 .…”

Section: Introductionmentioning

confidence: 99%

Integrated optical modulator manipulating the polarization and rotation handedness of Orbital Angular Momentum states

Mousavi

Nouroozi

Vallone

et al. 2017

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Recent studies demonstrated that the optical channels encoded by Orbital Angular Momentum (OAM) are capable candidates for improving the next generation of communication systems. OAM states can enhance the capacity and security of high-dimensional communication channels in both classical and quantum regimes based on optical fibre and free space. Hence, fast and precise control of the beams encoded by OAM can provide their commercial applications in the compatible communication networks. Integrated optical devices are good miniaturized options to perform this issue. This paper proposes a numerically verified integrated high-frequency electro-optical modulator for manipulation of the guided modes encoded in both OAM and polarization states. The proposed modulator is designed as an electro-optically active Lithium Niobate (LN) core photonic wire with silica as its cladding in a LN on Insulator (LNOI) configuration. It consists of two successive parts; a phase shifter to reverse the rotation handedness of the input OAM state and a polarization converter to change the horizontally polarized OAM state to the vertically polarized one. It is shown that all four possible output polarization-OAM encoded states can be achieved with only 6 V and 7 V applied voltages to the electrodes in the two parts of the modulator.In the past decades, interests in exploiting Orbital Angular Momentum (OAM) as a new degree of freedom for encoding the information in optical communication channels have been enhanced 1 . Utilizing this technique in classical communication based on both optical fibre 2 and free space 3-7 , and also in quantum communication 8-10 demonstrated a promising increased data transmission rate for the future networks. In addition, secure transmission is one of the concerns of communication systems. Besides the classical cryptography techniques, Quantum Cryptography (QC) improved the security between authorized partners connected by a quantum channel. Quantum Key Distribution (QKD) protocols are used intensively for approaches of QC. As an example, BB84 QKD protocol employs four states belonging to two conjugate bases (such as horizontal, vertical, left circular and right circular polarization states) for data encoding 11,12 . By combining polarization with OAM, generation of a rotation invariant qubit is possible. In this case, QKD is proved to be independent of alignment 13,14 . This toolbox can be a good choice for free-space optical and quantum communication with moving objects, such as satellites or flying platforms. The rotation invariant qubit in QKD has been operated experimentally over a distance of 210 m 15 . Moreover, the possibility of using OAM together with polarization for encoding the high-dimensional QKD states improves noise resistance and increase the content of information carried by each photon 16 . Carrier modes with phase term of exp(ilφ) have OAM corresponding to lℏ; per photon. In this term l (l = 0, ±1, ±2, …) is the topological charge of the mode and its sign determines the rotation handedness...

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“…Our experimental q-plate is a prototype from Citizen Holdings Co. [18] with 12 liquid crystal segments with a diameter of 2.5 cm, where q=1/2, as shown in Fig. 1(a).…”

mentioning

confidence: 99%

“…The phase of each segment can be varied using an applied voltage. The segmented structure of the device gives an excellent polarization conversion efficiency of 97.7% [18].…”

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confidence: 99%

Performance of a q-plate tunable retarder in reflection for the switchable generation of both first- and second-order vector beams

et al. 2015

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We examine the performance of a tunable liquid crystal q-plate in a reflective geometry. When the device is tuned to a half-wave retardance, it operates as a q-plate with twice the value (2q) by adding a quarter-wave retarder between the mirror and the q-plate. However, when the device is tuned to a quarter-wave retardance, it acts as the original q-plate without the retarder. Experimental results are shown. Using an input tunable polarization state generator, the system allows the switchable production of all states on both the first- and second-order Poincaré spheres.

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Analysis of a segmented q-plate tunable retarder for the generation of first-order vector beams

Cited by 41 publications

References 33 publications

Vector Beam Polarization State Spectrum Analyzer

Vector Beam Polarization State Spectrum Analyzer

Integrated optical modulator manipulating the polarization and rotation handedness of Orbital Angular Momentum states

Performance of a q-plate tunable retarder in reflection for the switchable generation of both first- and second-order vector beams

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