We proposed an approach for creating three-dimensional (3D) multifocal perfect vortices arrays by using a high numerical aperture objective. The position, orbital angular momentum states, number and diameter of the can be freely modulated special designed hybrid phase plate (HPP). HPP could calculated 3D shifting expression which is derived from Fourier transform theory Debye diffraction integral. Furthermore, we developed novel pixel checkerboard method adding information into HPP....

An air-core fiber imposed by torsion is investigated in this paper. We refer to kind of as twisted (TAF). It has been demonstrated that the eigenstates TAF consist guided optical vortex waves with different propagation constants a effective index. With increase twist rate, could separate OAM modes which are near degenerate or fiber. The separation conductive ultralong distance low crosstalk. be considered an ideal candidate for based communication. Moreover, we photonic crystal (TAPCF) can...

In this article, an ultra-sensitive temperature sensor based on the enhanced Vernier effect is presented. It consists of a double-groove cavity (DGC) and open (OC) filled with polydimethylsiloxane (PDMS). The length DGC limited by two single-mode fibers (SMFs), OC not limited. sensing cavities are affected thermal optic (TOE) expansion (TEE). Their interference dip spectra shifts to opposite directions, respectively, which realizes effect. sensitivity can be further improved, caused...

Circular airy beam (CAB) is a kind of new structured light with non-diffracting, self-focusing, and self-healing properties. Due to its wide applications, recently, numerous researchers have used various methods modulate this beam. We theoretically verify experimentally demonstrate the azimuthal modulation method shapes focal spot CAB by modulating azimuthally spliced power-exponential phase. The results show that after an phase, multi-focal spots can be generated on self-focusing plane...

We propose a highly efficient phase modulation method for generating an elliptic optical vortex with arbitrary controllable rotation angle, that can be recognized as degree of freedom. A transformation matrix and were used to realize the light field. numerically experimentally demonstrate control capability Bessel beam higher-order Laguerre–Gauss modes. The angle β, e multiplexing vortices could freely modulated by using proposed method. This work is important progress programmable tweezers,...

We present a simple method of spatial-division multiplexing/demultiplexing with orbital angular momentum (OAM) based on multi-ring optical fiber. Multi-ring fibers are ideal spatial division multiplexing carriers, providing more communication channels including orthogonal OAM and channels. propose an encoding scheme using perfect vortex array (MPVA) to make full use these achieve high-capacity data links. For improving the coupling efficiency, vortices whose radii independent topological...

We have proposed and experimentally demonstrated a dual-parameter optical fiber sensor for simultaneous measurement of magnetic field temperature. The is magnetofluid-coated single-mode (SMF)-U-shaped hollow-core (UHCF)-single-mode (SMF) (SMF-UHCF-SMF) structure. Combined with the intermodal interference macro-bending loss U-shaped structure, different bend diameters was investigated. In our experiments, transmission spectra varied strength temperature around sensing respectively. dip...

Features extraction is a key step in facial expression recognition system. In order to extract features that are subject-independent and robust illumination variety, this paper introduces algorithm. Given still image containing information, preprocessors executed firstly, which include sub-regions segmentation, grayscale scale normalization. Secondly, feature vectors of the extracted by Gabor wavelet transformation form elastic graph for expression. Finally, six basic expressions shown...

In this paper, we propose a curvature and temperature sensor based on two symmetrical grooves hollow core fiber (HCF) filled with polydimethylsiloxane (PDMS). The are produced by splicing both ends of the polished HCF multimode fibers (MMFs). proposed groove structure is sensitive to curvature, PDMS, high thermo-optical coefficient, makes highly temperature. experimental results show that exhibits sensitivity −6.833 nm/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Low temperature sensitivity and low spectral contrast are serious but common issues for most Fabry Perot (FP) sensors with an air cavity. In this paper, a high-temperature-sensitive spectrum-contrast-enhanced interferometer (FPI) is proposed experimentally demonstrated. The device composed of hollow cylindrical waveguide (HCW) filled polydimethylsiloxane (PDMS) semi-elliptic PDMS end face. face increases the significantly due to focusing effect. Experimentally, 11.97 dB, which two times...

Facial expression recognition technology plays an important role in research areas such as psychological studies, image understanding and virtual reality etc. In order to achieve subject-independent facial obtain robustness against illumination variety deformation, methods based on Gabor wavelet transformation elastic templates matching are presented this paper. First given a still containing information, preprocessors executed which include gray scale normalization. Secondly, filters...

Helically twisted microstructured optical fibers have a wide application prospect in the field of vortex communications. In this paper, helically single-ring photonic crystal fiber (HS-PCF) is proposed for orbital angular momentum (OAM) modes selective filtering. And theoretical framework OAMs filtering also constructed. Positive and negative OAM vortexes different transmission losses HS-PCF, loss difference between them increases significantly after twist rate reaches certain value. Such...

In this research, we proposed and experimentally verified a compact all-fiber sensor that can measure refractive index (RI) temperature simultaneously. Two segments of hollow-core fiber (HCF) are connected to the two ends four-core (FCF) as beam splitter coupler, then spliced with sections single-mode fibers (lead-in lead-out SMF), respectively. The excite higher-order modes recouple core into outgoing fiber, thereby forming inter-mode interference. different response sensitivities...

An ultra-sensitive contact force sensor based on a polymerized hollow-cylinder lying the end-face of single-mode fiber is proposed. The whole in single illumination with an annular beam, which generated by section multimode without resorting to any expensive instruments. It fixed UV-glue, working as Fabry-Perot cavity. Owing both hollow structure and low Young's modulus polymer, experimental results show sensitivity reaches high 1.08 nm / <inline-formula...

Orbital angular momentum (OAM) of light provides a new dimension to increase the communication capacity. The compact and miniaturized devices are preferred because advantages in reliability easy integration. In this work, quarter-ring-shaped phase-gradient metasurface (QR-PGM) is proposed sort various propagating waves into fully separated waveguide channels according their OAM states. principle based on focal spot shifting arising from constructive interference surface plasmon polaritons...

A mode convertor was proposed and investigated for generating vortex modes in a ring-core fiber based on plasmonic q-plate (PQP), which is composed of specially organized L-shaped resonator (LSR) arrays. multicore used to transmit fundamental modes, the LSR arrays were modulate phases these modes. Behind PQP, transmitted with gradient phase distribution can be considered as incident lights broadband filter. The topological charges generated various by using an optical PQP different q,...

Optical vortex beams with orbital angular momentum (OAM) have recently received considerable attention in high-speed optical communication due to their spatial orthogonality. For realizing undamaged demultiplexing, an all-dielectric multiplexed metasurface for demultiplexing wavelength-division multiplexing and polarization-division OAM light was proposed. This demultiplexer works the near-infrared spectral region transmitted carry original topological charges phase distribution. It is worth...

A scheme of fiber Fabry-Perot (F-P) cavity refractive index (RI) demodulation named under-sampled length spectrum retrieval (ULSR) is proposed. Unlike the wavelength method, ULSR can be used for physical quantity detection with just a monochromatic laser and photodetectors, avoiding need wideband lasers or expensive infrared spectrometers. Eight F-P cavities different lengths were fabricated to sample spectrum, then obtained was demodulate RI fillings. It demonstrated that system achieve an...

A switchable compact plasmonic grating coupler is proposed and demonstrated theoretically. It excited by TM standing waves can be used to modulate the intensity of radiated light moving position waves. The for connection composed five gold strips a reflector, it's footprint only 2.19 μm × 3.19 μm. calculation results show that bandwidth 110 nm from 1.5 1.61 μm, extinction ratio reach 20 dB at λ = 1.55 with ON-radiation efficiency bigger than 82%. Meanwhile, thermal loss rate no more 8%....