Generation Of Cylindrical Vector Beams Research Articles

Generation of arbitrary cylindrical vector beams by an all-fiber coherent beam combining system

Generation of arbitrary cylindrical vector beams by an all-fiber coherent beam combining system

Cylindrical vector beam generation from a hybrid multimode Q-switched mode-locked fiber laser

We demonstrate a hybrid multimode Q-switched mode-locked fiber laser capable of delivering cylindrical vector beams (CVBs). The wavelength-tunable Q-switching, conventional mode-locking, Q-switched mode-locking (QML), and CVB generation under QML operation are respectively achieved in this hybrid multimode cavity. The mode-locking mechanism is based on carbon nanotubes as saturable absorber and two interferometric filtering structures, i.e., multimode fiber-single-mode fiber-multimode fiber and multimode fiber-few-mode fiber-multimode fiber. The mode-selective coupler is used as a mode selector converting the fundamental mode to higher-order mode and as an output coupler to obtain CVB. The Q-switched pulses allow for tunable wavelengths in the range of 1028.2 nm to 1038.2 nm, with a frequency of about 50 KHz. The conventional mode-locking is achieved with a repetition frequency of 15.6 MHz and a pulse interval of 66.7 ns. Specifically, the introduction of dual interferometric filtering structures in the cavity results in noteworthy nonlinear effects, facilitating the generation of third-harmonic mode-locking under the single-wavelength QML operation. These experimental findings highlight the promising applications such as mode-division multiplexed optical communication and laser processing.

Monolayer Chiral Metasurface for Generation of Arbitrary Cylindrical Vector Beams

The cylindrical vector beam (CVB) has been widely studied and applied in recent years. However, many CVB generation methods suffer from complex systems, and large-size devices are required. Here, we propose a monolayer chiral metasurface composed of spin-sensitive unit cells which can generate different holograms for left- and right-circular polarization based on the combined modulation of geometric phase and detour phase. With a linearly polarized incident beam, the metasurface can generate CVBs with controllable polarization angles and orders, and even more complex vector beams. This work provides a new idea for the design of miniaturized optical devices for generating arbitrary vector beams.

Mid-infrared pulsed Er:ZBLAN fiber laser producing mode-switchable cylindrical vector beams.

We demonstrate the generation of both continuous-wave (CW) and Q-switched cylindrical vector beams (CVBs) from a mid-infrared Er3+-doped ZBLAN (Er:ZBLAN) fiber laser at ∼ 2.8 µm. A customized S-waveplate is incorporated as the intracavity mode converter to achieve the mid-infrared CVBs. Switchable modes of CVBs between the radially and azimuthally polarized beam can be realized easily by manipulating the cavity conditions. A maximum output power of ∼250 mW is achieved for the CW CVBs. In the short-pulsed CVBs operation regime, both the active and passive Q-switching modes are realized with a pulse duration of hundreds of nanoseconds. The proposed mid-infrared cylindrical vector lasers can have significant potential for applications in biomedicine, optical trapping, material processing and optical communication.

On-chip generation of adjustable cylindrical vector beams.

Cylindrical vector (CV) beams have sparked considerable interest due to their extraordinary vectorial properties, desirable for applications ranging from microscopy to high energy physics. Increasing demand for cost-effective, small-footprint photonics has fueled the development of photonic integrated circuits (PICs) capable of generating structured light beams in recent years. This technology however suffers from low reconfigurability, limiting the variety of CV beams that can be generated from these devices. In this article, we propose a novel design to overcome this limitation, which exploits the polarization-dependent response of annular gratings embedded into a microring resonator to generate re-configurable CV beams. We demonstrate the viability of the device in a proof-of-principle experiment including spatially resolved Stokes measurements.

Tight focusing field of cylindrical vector beams based on cascaded low-refractive index metamaterials

Abstract Using low-refractive-index metamaterials, we design a transmission-type radial-angular cylindrical vector beam generator. A high numerical aperture lens is constructed using an asymmetric meta-grating structure. The metamaterial vector beam generator and the meta-grating lens are physically cascaded to obtain the tight focusing characteristics of the vector light field. The vector beam generator module and the meta-lens module are prepared by 3D printing technology, and the near-field test has been carried out on the samples in the terahertz band. Using the physical cascading method, two modules are cascaded to construct a vector beam tight focusing device, and the focusing electric field distribution test has been carried out. The use of 3D printing technology for sample preparation further reduces the manufacturing difficulty and production cost, and ensures the realization of its design function on the basis of miniaturization and light weight, which provides the possibility for the research of tight focusing field regulation in the terahertz band.

Generation of mode-switchable nanosecond pulsed cylindrical vector beams and vortex beams from a Q-switched solid-state laser

We reported and demonstrated a Q-switched solid-state laser for the generation of mode-switchable nanosecond pulsed cylindrical vector beams and vortex beams between different orders. In the cavity, an order-switchable Q-plate, consisted of two Q-plates and two quarter wave plates, was applied to achieve the mode-switch between two different orders by adjusting the angles of quarter wave plates. Besides, two extra quarter wave plates and a Faraday rotator were utilized to realize the intracavitary self-reproducibility of cylindrical vector beams and vortex beams, respectively. The experimental results show that by using two Q-plates of 1st and 3rd orders, the cylindrical vector beams and vortex beams of 2nd and 4th orders can be directly generated from the solid-state laser. For the 2nd order cylindrical vector beam and vortex beam, the slope efficiency, pulse width, and repetition rate are 7.2%, 415 ns, and 227 kHz, respectively. To the best of our knowledge, it is the first time to realize the controlled generation of mode-switchable cylindrical vector beams and vortex beams between two different orders from a solid-state laser.

Rocking filter in a highly birefringent fiber for resonant coupling between different LP11 modes and generation of cylindrical vector beams.

We present a rocking filter in a highly birefringent two-mode fiber that enables resonant coupling between different modes in the LP11 group. Our simulations and experimental results prove that such a filter allows for resonant coupling between orthogonally polarized LP11 modes of the same spatial structure, as well as between modes of the same polarizations and orthogonal spatial distributions. Furthermore, we demonstrate that such rocking filters can be used to generate pure TE01, TM01 and HE21 beams or their coherent superposition.

2 µm cylindrical vector beam generation from a c-cut Tm:CaYAlO4 crystal resonator.

Different from the traditional ideal column symmetry cavities, we directly generated the cylindrical vector pulsed beams in the folded six-mirror cavity by employing a c-cut Tm:CaYAlO4 (Tm:CYA) crystal and SESAM. By adjusting the distance between the curved cavity mirror (M4) and the SESAM, both the radially polarized beam and azimuthally polarized beam are generated around 1962 nm and the two vectorial modes can be freely switched in the resonator. Further increased the pump power to 7 W, the stable radially polarized Q-switched mode-locked (QML) cylindrical vector beams were also obtained with an output power of 55 mW, the sub-pulse repetition rate of 120.42 MHz, pulse duration of ∼0.5 ns and the beam quality factor M2 of ∼2.9. To our knowledge, this is the first report of radially and azimuthally polarized beams in the 2 µm wavelength solid-state resonator.

Generation of cylindrical vector beam from GaAs/InGaAs/GaAs core-multishell nanowire cavity

We investigated the beam profiles and polarization states in the low-temperature photoluminescence from vertical GaAs/InGaAs/GaAs core-multishell nanowire (NW) under continuous-wave and pulsed excitations. In the beam profile under pulsed excitation, a doughnut-shaped intensity distribution was confirmed. The beam was shown to exhibit an axisymmetric distribution in the polarization. These observations indicate that cylindrical vector beams were generated from the NW. The observed polarization did not correspond to low-order vector beams but suggested the generation of higher-order beams.

Cylindrical vector beam generator on photonic crystal cavity integrated with metal split ring nanoresonators

We propose a chip-integratable cylindrical vector (CV) beam generator by integrating six plasmonic split ring resonators (SRRs) on a planar photonic crystal (PPC) cavity. The employed PPC cavity is formed by cutting six adjacent air holes in the PPC center, which could generate a CV beam with azimuthally symmetric polarizations. By further integrating six SRRs on the structure defects of the PPC cavity, the polarizations of the CV beam could be tailored by controlling the opening angles of the SRRs, e.g., from azimuthal to radial symmetry. The mechanism is governed by the coupling between the resonance modes in SRRs and PPC cavity, which modifies the far-field radiation of the resonance mode of the PPC cavity with the SRR as the nano-antenna. The integration of SRRs also increases the coupling of the generated CV beam with the free-space optics, such as an objective lens, promising its further applications in optical communication, optical tweezer, imaging, etc.

Controlled generation of order-switchable cylindrical vector beams from a Nd:YAG laser

Controlled generation of order-switchable cylindrical vector beams from a Nd:YAG laser

Cylindrical vector beam generation from a passively mode-locked Raman fiber laser

We experimentally investigate cylindrical vector beam (CVB) generation from a passively mode-locked Raman fiber laser. The mode-locked Raman fiber lasers based on nonlinear polarization rotation (NPR), utilize the Raman gain resulted from the stimulated Raman scattering (SRS) effect in passive fibers, instead of stimulated emission amplification of active fibers in conventional mode-locked fiber lasers. With a mode-selective coupler (MSC) incorporated into the mode-locked Raman fiber laser, the generation of CVBs has been realized. In experiment, using a Raman pump source of 1454 nm, mode-locked CVB output with central wavelength of 1562 nm was obtained. The output polarization state can be switched between the radial and azimuthal polarization states, and the beam purity is above 90%. Due to the broadband Raman gain in optical fiber, the CVB output with the desired wavelength is available in principle by selecting a suitable pump source. This kind of flexible wavelength CVB Raman fiber laser may have potential applications in optical communications and fiber optics.

Generation of cylindrical vector beams in a linear cavity mode-locked fiber laser based on nonlinear multimode interference.

In this paper, a linear cavity mode-locked pulsed fiber laser generating cylindrical vector beams (CVBs) is proposed and demonstrated based on a nonlinear multimode interference. A homemade long-period fiber grating with a broad bandwidth of 121 nm is used as a mode converter inside the cavity. The saturable absorber was formed by single-mode fiber-graded index multimode fiber-single mode fiber (SMF-GIMF-SMF) structure. By controlling the pump power, the operation states are switchable among continuous-wave, Q-switched mode-locked (QML), and mode-locked regimes. The repetition rate of the QML CVB pulse envelope varies from 57.4 kHz to 102.7 kHz at the pump range of 118 to 285 mW. When increasing pump power to 380 mW, mode-locked CVB pulse repetition rate of 3.592 MHz, and pulse duration of 4.62 ns are achieved. In addition, the maximum single-pulse envelope energy can reach 510 nJ, and 142 mW average-power CVBs with a slope efficiency of as high as 20.2% can be obtained. Moreover, azimuthally and radially polarized beams can be obtained with mode purity over 95% in different operating regimes. The proposed fiber laser has a simple structure, and the operation is controllable in both temporal and spatial domains, which presents a flexible pulsed CVB source for application of laser processing, time or mode division multiplexing system, and spatiotemporal nonlinear optics.

Cylindrical Vector Beam Generation from a Passively Mode-Locked Raman Fiber Laser

Cylindrical Vector Beam Generation from a Passively Mode-Locked Raman Fiber Laser

High-Order Cylindrical Vector Beam Generation and Its Polarization Detection Based on Cascade Vortex Half-Wave Plates

High-Order Cylindrical Vector Beam Generation and Its Polarization Detection Based on Cascade Vortex Half-Wave Plates

Mid-infrared cylindrical vector beams enabled by dielectric metasurfaces

Over the last decade, photonics in the mid-infrared (mid-IR) frequency range had major advances in both generation and detection of light. However, efficient manipulation of the mid-IR light still faces many challenges. Spatially inhomogeneous control over the wavefront and polarization of mid-IR radiation is particularly difficult. Many standard techniques used for visible and near-infrared frequencies, such as liquid crystal-based spatial light modulation, are not applicable in the mid-IR due to unfavorable material properties in that spectral range. Here, we demonstrate spatially inhomogeneous polarization control of the mid-infrared light using custom-designed vortex retarders. Vortex retarders, while being widely used in the near-infrared and visible spectral ranges for generation of cylindrical vector beams, have been missing in the mid-infrared spectral range. Our implementation of mid-infrared vortex retarders is based on the concept of metasurfaces. We demonstrate metasurface-based vortex retarders at the wavelengths of 2.9 and 3.5 μm. We compare the performance of all-dielectric metasurface vortex retarders with the elements arranged in square and hexagonal lattices [Arbabi et al., Nat. Nanotechnol. 10, 937–943 (2015) and Arbabi et al., Nat. Commun. 6, 7069 (2015)]. Our work could accelerate the adoption of metasurfaces for the development of novel classes of mid-infrared optical components.

Practical generation of arbitrary high-order cylindrical vector beams by cascading vortex half-wave plates

A practical direct-view scheme for generating arbitrary high-order cylindrical vector (HCV) beams by cascading vortex half-wave plates (VHPs) is presented. The combination of odd number 2n-1 VHPs for n≥1 can realize (m2n-1-m2n-2+…+m1)-order CV beams, in which m is the order number of VHP and the corresponding subscript 2n-1 represents the arrangement number of VHPs, and the cascading of even number 2n ones can obtain (m2n-m2n-1+…+m2-m1)-order CV beams. All 1-12 order CV beams, including the high-order anti-vortex CV (ACV) beams, are generated only by selectively cascading the VHPs with m=1, 3 and 8. The polarization properties of the generated HCV beams are investigated by measuring the corresponding Stokes parameters. It is experimentally demonstrated that arbitrary HCV beams are effectively achieved by the proposed method. The order numbers of CV beams can be greatly expanded by cascading limited types of VHPs.

Efficient generation of annular cylindrical vector beams by refractive axicons with high-transmission thin-film retarders

A new type of energy-efficient thin-film-coated (TF) conical optics is presented that combines annular beam shapers and cylindrical polarization converters to transform a linearly polarized laser beam into annular cylindrical vector beams. The main operational steps of the polarization converters include the generation of a circularly polarized vortex beam, the compensation of a quarter-wave shift between its p- and s-polarized components, and the summation of these components, with the last two steps being carried out simultaneously by means of such key elements as conically illuminated high-transmission TF retarders. Three optical configurations are considered and analyzed, of which the TF retarders are located on the conical surfaces of two refractive beam-shaping axicons. The total light throughput of such configurations approach 100% and they are suitable for operation at deep UV wavelengths and high power density. As potential elements of these configurations, five TF retarders are designed and optimized at a wavelength of 266 nm. Numerical simulations and comparison of the angular and spectral characteristics of these TF retarders confirm that they comply with the tolerances on the acceptable deviations of axicon wedge angles and wavelengths of typical high-power CW lasers with the above wavelength. Also presented are the results of a tolerance analysis of the TF retarders with respect to their TF thicknesses.

Arbitrary cylindrical vector beam generation enabled by polarization-selective Gouy phase shifter

Cylindrical vector beams (CVBs), which possess polarization distribution of rotational symmetry on the transverse plane, can be developed in many optical technologies. Conventional methods to generate CVBs contain redundant interferometers or need to switch among diverse elements, thus being inconvenient in applications containing multiple CVBs. Here we provide a passive polarization-selective device to substitute interferometers and simplify generation setup. It is accomplished by reversing topological charges of orbital angular momentum based on a polarization-selective Gouy phase. In the process, tunable input light is the only condition to generate a CVB with arbitrary topological charges. To cover both azimuthal and radial parameters of CVBs, we express the mapping between scalar Laguerre–Gaussian light on a basic Poincaré sphere and CVB on a high-order Poincaré sphere. The proposed device simplifies the generation of CVBs enormously and thus has potential in integrated devices for both quantum and classic optical experiments.