### Zeroth- and first-order long range non-diffracting GausstextendashBessel beams generated by annihilating multiple-charged optical vortices

Author(s):

Stoyanov, Lyubomir; Zhekova, Maya; Stefanov, Aleksander; Stefanov, Ivan; Paulus, Gerhard G. & Dreischuh, Alexander

Abstract:

“We demonstrate an alternative approach for generating zeroth- and first-order long range non-diffracting Gauss–Bessel beams (GBBs). Starting from a Gaussian beam, the key point is the creation of a bright ring-shaped beam with a large radius-to-width ratio, which is subsequently Fourier-transformed by a thin lens. The phase profile required for creating zeroth-order GBBs is flat and helical for first-order GBBs with unit topological charge (TC). Both the ring-shaped beam and the required phase profile can be realized by creating highly charged optical vortices by a spatial light modulator and annihilating them by using a second modulator of the same type. The generated long-range GBBs are proven to have negligible transverse evolution up to 2 m and can be regarded as non-diffracting. The influences of the charge state of the TCs, the propagation distance behind the focusing lens, and the GBB profiles on the relative intensities of the peak/rings are discussed. The method is much more efficient as compared to this using annular slits in the back focal plane of lenses. Moreover, at large propagation distances the quality of the generated GBBs significantly surpasses this of GBBs created by low angle axicons. The developed analytical model reproduces the experimental data. The presented method is flexible, easily realizable by using a spatial light modulator, does not require any special optical elements and, thus, is accessible in many laboratories.”

Publication: Scientific Reports
Issue/Year: Scientific Reports, Volume 10; Number 1; 2020
DOI: 10.1038/s41598-020-78613-7

### Direct comparison of anti-diffracting optical pin beams and abruptly autofocusing beams

Author(s):

Denghui Li, Domenico Bongiovanni, Michael Goutsoulas, Shiqi Xia, Ze Zhang, Yi Hu, Daohong Song, Roberto Morandotti, Nikolaos K. Efremidis, and Zhigang Chen

Abstract:

“We propose and demonstrate a generalized class of anti-diffracting optical pin-like beams (OPBs). Such beams exhibit autofocusing dynamics while morphing into a Bessel-like shape during long-distance propagation, where the size of their main lobe can be tuned by an exponent’s parameter. In particular, their amplitude envelope can be engineered to preserve the pin-like peak intensity pattern. In both theory and experiment, the OPBs are directly compared with radially symmetric abruptly autofocusing beams (AABs) under the same conditions. Furthermore, enhanced transmission and robustness of the OPBs are observed while traversing a scattering colloidal suspension, as compared to both AABs and conventional Bessel beams.”

Publication: OSA Continuum
Issue/Year: Vol. 3, Issue 6, pp. 1525-1535 (2020)
DOI: 10.1364/OSAC.391878

### Rotational Doppler shift upon reflection from a right angle prism

Author(s):

O. Emile, J. Emile and C. Brousseau

Abstract:

“This Letter reports the observation of a rotational Doppler shift on reflected beams carrying Orbital Angular Momentum (OAM). More precisely, we study the beat frequency of two optical beams carrying OAM with opposite signs, reflected on a right angle prism. We show that the interference of the two beams leads to a daisy-like pattern that rotates at twice the rotating frequency of the prism. The rotational Doppler frequency shift is equal to the OAM topological charge change times the rotational frequency. Possible applications in the positioning and detection of rotation of objects are then discussed.
This publication was supported by the European Union through the European Research Development Fund (ERDF) and the French Region of Brittany, Ministry of High Education and Research, Rennes Métropole and Conseil Départemental 35, through The CPER project SOPHIE/STIC and Ondes. We wish to acknowledge valuable discussions with Professor K. Mahdjoubi (Université de Rennes 1).”

Publication: Applied Physics Letters
Issue/Year: Appl. Phys. Lett. Volume:116 (2020)
DOI: 10.1063/5.0009396

### Non-interferometric technique to realize vector beams embedded with polarization singularities

Author(s):

Praveen Kumar, Sushanta Kumar Pal, Naveen K. Nishchal, and P. Senthilkumaran

Abstract:

“In this paper, we present a simple and flexible non-interferometric method to generate various polarization singularity lattice fields. The proposed method is based on a double modulation technique that uses a single reflective spatial light modulator to generate different lattice structures consisting of V-point and C-point polarization singularities. The present technique is compact with respect to previous experimental realization techniques. Different structures having star and lemon fields are generated without altering the experimental setup. In addition, the same setup can be used to obtain different types of inhomogeneous fields embedded with isolated polarization singularities even of higher orders. The Stokes polarimetry method has been used to obtain the polarization distributions of generated fields, which are in good agreement with simulated results.”

Publication: Journal of the Optical Society of America A
Issue/Year: Vol. 37, Issue 6, pp. 1043-1052 (2020)
DOI: 10.1364/JOSAA.393027

### Optical vortex with multi-fractional orders

Author(s):

Juntao Hu, Yuping Tai, Liuhao Zhu, Zixu Long, Miaomiao Tang, Hehe Li, Xinzhong Li and Yangjian Cai

Abstract:

“Recently, optical vortices (OVs) have attracted substantial attention because they can provide an additional degree of freedom, i.e., orbital angular momentum (OAM). It is well known that the fractional OV (FOV) is interpreted as a weighted superposition of a series of integer OVs containing different OAM states. However, methods for controlling the sampling interval of the OAM state decomposition and determining the selected sampling OAM state are lacking. To address this issue, in this Letter, we propose a FOV by inserting multiple fractional phase jumps into whole phase jumps (2π), termed as a multi-fractional OV (MFOV). The MFOV is a generalized FOV possessing three adjustable parameters, including the number of azimuthal phase periods (APPs), N; the number of whole phase jumps in an APP, K; and the fractional phase jump, α. The results show that the intensity and OAM of the MFOV are shaped into different polygons based on the APP number. Through OAM state decomposition and OAM entropy techniques, we find that the MFOV is constructed by sparse sampling of the OAM states, with the sampling interval equal to N. Moreover, the probability of each sampling state is determined by the parameter α, and the state order of the maximal probability is controlled by the parameter K, as K * N. This work presents a clear physical interpretation of the FOV, which deepens our understanding of the FOV and facilitates potential applications, especially for multiplexing technology in optical communication based on OAM.
This work was supported by the National Natural Science Foundation of China (NSFC) (Nos. 11974102, 11525418, 91750201, and 11974218), the Open Research Fund of State Key Laboratory of Transient Optics and Photonics, CAS (No. SKLST201901), the Innovation Group of Jinan under Grant No. 2018GXRC010, and the National key Research and Development Project of China (2019YFA0705000).”

Publication: Applied Physics Letters
Issue/Year: Appl. Phys. Lett. Volume:116 (2020)
DOI: 10.1063/5.0004692

### Flexible measurement of high-order optical orbital angular momentum with a variable cylindrical lens pair

Author(s):

Jianneng Lu, Chongyang Cao, Zhuqing Zhu and Bing Gu

Abstract:

“We present a method to measure the high-order optical orbital angular momentum (OAM) with a variable cylindrical lens pair. The optical system consists of two cylindrical lenses with the opposite focal length. It produces a rotating position—spatial frequency transformation of phase modulation by changing the angle between the two cylindrical lenses. With this feature, the method can flexibly measure the OAM states of the vortex beams with different beam waists. The OAM states are determined by the number and direction of dark stripes of the diffraction pattern. The measurements of the topological charge and the radial index of Laguerre–Gaussian mode are demonstrated. As a compact high-order OAM measuring device, the variable cylindrical lens pair may find potential applications in optical communication.
This work was funded by the National Natural Science Foundation of China (Nos. 11774055 and 61875093), the Natural Science Foundation of Jiangsu Province of China (No. BK20181384) and the Natural Science Foundation of Tianjin of China (No. 19JCYBJC16500).”

Publication: Applied Physics Letters
Issue/Year: Appl. Phys. Lett. Volume:116 (2020)
DOI: 10.1063/5.0002756

### Generation of composite vortex beams by independent Spatial Light Modulator pixel addressing

Author(s):

Mateusz Szatkowski, Jan Masajada, Ireneusz Augustyniak and Klaudia Nowacka

Abstract:

“The composite optical beams being a result of superposition, are a promising way to study the orbital angular momentum and its effects. Their wide range of applications makes them attractive and easily available due to the growing interest in the Spatial Light Modulators (SLM). In this paper, we present a simple method for generating composite vortex patterns with high symmetry. Our method is simple, flexible and gives perfectly aligned beams, insensitive to mechanical vibrations. This method is based on the ability to split SLM cells between phase patterns that are to be superposed. This approach allows control of the intensity relation between those structures, enables their rotation and is capable to superpose more than two such structures.
In this paper, we examine its ability to produce superposition of two optical vortices by presenting both theoretical and experimental results. ”

Publication: Optics Communications
Issue/Year: Volume 463
DOI: 10.1016/j.optcom.2020.125341

### Anomalous ring-connected optical vortex array

Author(s):

Xinzhong Li and Hao Zhang

Abstract:

“In this study, an anomalous ring-connected optical vortex array (ARC-OVA) via the superposition of two grafted optical vortices (GOVs) with different topological charges (TCs) has been proposed. Compared with conventional OVAs, the signs and distribution of the OVs can be individually modulated, while the number of OVs remains unchanged. In particular, the positive and negative OVs simultaneously appear in the same intensity ring. Additionally, the size of the dark core occupied by the OV can be modulated, and the specific dark core is shared by a pair of plus–minus OVs. This work deepens our knowledge about connected OVAs and facilitates new potential applications, especially in particle manipulation and optical measurement.”

Publication: Optics Express
Issue/Year: Vol. 28, Issue 9, pp. 13775-13785
DOI: 10.1364/OE.390985

### Super-resolved angular displacement estimation based upon a Sagnac interferometer and parity measurement

Author(s):

Jian-Dong Zhang, Zi-Jing Zhang, Long-Zhu Cen, Jun-Yan Hu and Yuan Zhao

Abstract:

“Super-resolved angular displacement estimation is of crucial significance to the field
of quantum information processing. Here we report an estimation protocol based on a Sagnac
interferometer fed by a coherent state carrying orbital angular momentum. In a lossless scenario,
through the use of parity measurement, our protocol can achieve a 4-fold super-resolved output
with quantum number ; meanwhile, a shot-noise-limited sensitivity saturating the quantum
Cramér-Rao bound is reachable. We also consider the effects of several realistic factors, including
nonideal state preparation, photon loss, and inefficient measurement. Finally, with mean photon
number 𝑁¯ = 2.297 and ℓ = 1 taken, we experimentally demonstrate a super-resolved effect of
angular displacement with a factor of 7.88.”

Publication: Optics Express
Issue/Year: Vol. 28, Issue 3, pp. 4320-4332
DOI: 10.1364/OE.384082

### Generation of Tunable Fractional Vector Curvilinear Beams With Controllable Phase Distribution

Author(s):

Fengyan Gu, Zhongzheng Gu, Chenliang Chang, Caojin Yuan, Shaotong Feng, Fangjian Xing and Shouping Nie

Abstract:

“An approach to generate the tunable fractional vector curvilinear beams (VCBs) was proposed. The scheme is based on the vector optical field generator (VOFG) system, where the two orthogonal polarized scalar curvilinear beams (SCBs) are generated to be the base vector components, and coaxially superposed by a Ronchi grating. We design a new phase distribution with several loops of 0 to π in order to generate more dark gaps. The phase distribution becomes nonuniform by varying the phase variation rate and the positions of the dark gaps are changed. Using the different parameters of the curves, the fractional VCBs with different shapes are achieved. The two orthogonal polarized SCBs with the opposite topological charges are modulated to perform the beam conversion by a phase-only computer-generated hologram (CGH). Our experimental results comply with the theory and the radial opening of the dark gaps may have some applications for guiding and transporting particles.”