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Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate full-color and hyperspectral imaging. By contrast, large dispersion holds opportunities for spectroscopy and tomography. Combining both functions into a single component will significantly enhance its versatility. A strategy is proposed to delicately integrate two lenses with a static resonant phase and a switchable geometric phase separately. The former is a metasurface lens with a linear phase dispersion. The latter is composed of liquid crystals (LCs) with space-variant orientations with a phase profile that is frequency independent. By this means, a broadband achromatic focusing from 0.9 to 1.4 THz is revealed. When a saturated bias is applied on LCs, the geometric phase modulation vanishes, leaving only the resonant phase of the metalens. Correspondingly, the device changes from achromatic to dispersive. Furthermore, a metadeflector with tunable dispersion is demonstrated to verify the universality of the proposed method. Our work may pave a way toward active metaoptics, promoting various imaging applications.

Integrated photonics provides a route both to miniaturize quantum key distribution (QKD) devices and to enhance their performance. A key element for achieving discrete-variable QKD is a single-photon detector. It is highly desirable to integrate detectors onto a photonic chip to enable the realization of practical and scalable quantum networks. We realize an integrated heterogeneous superconducting-silicon-photonic chip. Harnessing the unique high-speed feature of our optical waveguide-integrated superconducting detector, we perform the first optimal Bell-state measurement (BSM) of time-bin encoded qubits generated from two independent lasers. The optimal BSM enables an increased key rate of measurement-device-independent QKD, which is immune to all attacks against the detection system, and hence provides the basis for a QKD network with untrusted relays. Together with the time-multiplexed technique, we have enhanced the sifted key rate by almost one order of magnitude. With a 125 MHz clock rate, we obtain a secure key rate of 6.166 kbps over 24.0 dB loss, which is comparable to the state-of-the-art MDI-QKD experimental results with GHz clock rate. Combined with integrated QKD transmitters, a scalable, chip-based and cost-effective QKD network should become realizable in the near future., Comment: Major updates: 1. Realize optimal Bell-state measurement for time-bin qubits; 2. With a 125 MHz clock rate, the generated secure key rate is comparable to the state-of-the-art MDI-QKD experimental results with GHz clock rate

The coding metasurface integrated with tunable materials offers an attractive alternative to manipulate the THz beam dynamically. In this work, we demonstrate a THz programmable metasurface based on liquid crystal. The phase profile on the metasurface could be dynamically manipulated by switching the “0” and “1” states of each element. The programmable metasurface could deflect the THz beam using the designed coding sequence, and a maximum deflection angle of 32° has been achieved. The presented design opens a route of beamforming for THz communication.

Ultrafast lasers generating high-repetition-rate ultrashort pulses through various mode-locking methods can benefit many important applications, including communications, materials processing, astronomical observation, etc. For decades, mode-locking based on dissipative four-wave-mixing (DFWM) has been fundamental in producing pulses with repetition rates on the order of gigahertz (GHz), where multiwavelength comb filters and long nonlinear components are elemental. Recently, this method has been improved using filter-driven DFWM, which exploits both the filtering and nonlinear features of silica microring resonators. However, the fabrication complexity and coupling loss between waveguides and fibers are problematic. We demonstrate a tens- to hundreds- of gigahertz-stable pulsed all-fiber laser based on a hybrid plasmonic microfiber knot resonator device. Unlike previously reported pulse generation mechanisms, the operation utilizes the nonlinear-polarization-rotation (NPR) effect introduced by the polarization-dependent feature of the device to increase intracavity power for boosting DFWM mode-locking, which we term NPR-stimulated DFWM. The easily fabricated versatile device acts as a polarizer, comb filter, and nonlinear component simultaneously, thereby introducing an application of microfiber resonator devices in ultrafast and nonlinear photonics. We believe that our work underpins a significant improvement in achieving practical low-cost ultrafast light sources.

We experimentally demonstrate the use of a periodically poled LiNbO3 (PPLN) crystal to produce an ultra-long sub-diffraction optical needle via second-harmonic generation. When we input a radially polarized fundamental wave from a femtosecond laser, a sub-diffraction beam size of 0.45λSH and an ultra-long depth of focus (DOF) of 55λSH are experimentally realized, where λSH is the second harmonic wavelength. The lateral size of the second harmonic optical needle is reduced by a factor of 2 compared to the case using the fundamental wave. The compact experimental configuration can realize wavelength conversion and wave-front shaping simultaneously in a single PPLN crystal. In addition, the ultra-long DOF is potentially useful in observing thick samples. The unique characteristics of our second harmonic optical needle open the door for practical applications in super-resolution imaging and optical manipulation.

The higher-order Poincare (HOP) sphere beam generalizes optical vortices and vector beams, vividly illustrating their higher-order polarization states. However, its doughnutlike intensity profile varies significantly with topological charge, restricting its application in optics. The authors study a perfect HOP sphere, whose annular intensity profile is $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t$ of topological charge. Single- and multiringed beams are produced in anisotropic medium, by exploiting a spiral geometric phase and aptly designed gratings. This work provides an exciting technique for manipulating the angular momentum of light, to improve $e.g.$ optical tweezers, or multiplexing in optical communication.

We first develop a large birefringence liquid crystal (LC) material in terahertz (THz) range. Then broadband tunable transmissive driven with porous graphene and reflective THz waveplates based on this LC are proposed. Furthermore, graphene-assisted high efficiency tunable THz metamaterial absorber is demonstrated. Finally, visible measurement of THz power based on capsulized cholesteric LC film is introduced.

Manipulating photon’s orbital angular momentum (OAM) through nonlinear interactions has drawn increasing research interests in recent years. In this work, we propose a scheme to control the OAM of the third harmonic wave through two cascaded second-order nonlinear processes. A Gaussian beam was frequency doubled at the first stage. Subsequent sum frequency mixing of the Gaussian second harmonic wave and an orthogonal-polarized Laguerre-Gaussian-like fundamental wave generate the third harmonic wave, which carries the same OAM as that of the Laguerre-Gaussian-like fundamental wave. In this experiment, we demonstrated controlling the OAM of the third harmonic wave in a tandem periodically-poled LiTaO3 optical superlattice, and the results are in accordance with theoretical predictions.

In recent years, the two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted renewed interest owing to their remarkable physical and chemical properties. Similar to that of graphene, the atomic thickness of TMDCs significantly limits their optoelectronic applications. In this study, we report a hybrid WS2-optical-fiber-nanowire (WOFN) structure for broadband enhancement of the light–matter interactions, i.e., light absorption, photoluminescence (PL) and second-harmonic generation (SHG), through evanescent field coupling. The interactions between the anisotropic light field of an optical fiber nanowire (OFN) and the anisotropic second-order susceptibility tensor of WS2 are systematically studied theoretically and experimentally. In particular, an efficient SHG in the WOFN appears to be 20 times larger than that in the same OFN before the WS2 integration under the same conditions. Moreover, we show that strain can efficiently manipulate the PL and SHG in the WOFN owing to the large configurability of the silica OFN. Our results demonstrate the potential applications of waveguide-coupled TMDCs structures for tunable high-performance photonic devices., Optical fiber nanowires: A tunable light source all wrapped up Coating an optical fiber nanowire in an ultrathin film of tungsten sulfide enhances its optical properties for use in tiny photonic devices. Transition metal dichalcogenides are semi-conducting materials which, like graphene, demonstrate valuable and unique physical properties when they are thinned down to single molecular layers. Fei Xu and Yan-qing Lu at Nanjing University, China and co-workers achieved tunable, enhanced light emission from an optical fiber nanowire by wrapping it in an ultrathin layer of tungsten disulfide (WS2). They showed that second harmonic generation – the generation of higher-energy photons - was twenty times greater in their hybrid design than in a bare nanowire. Further, by placing strain on the wire, the researchers could manipulate photon-electron and photon-photon interactions in WS2, allowing control over optical properties including photoluminescence.

A waveband-selective diffraction device, possessing dynamic and reversible light manipulation of its waveband-selectivity within a wide spectral range (∼140 nm), was developed by micro-patterning of a photoresponsive self-organized helical liquid crystal superstructure. Distinct from a conventional liquid crystal diffraction device, applied in a wide band from ultraviolet to near infrared wherein the diffracting light is due to the alternate phase modulation caused by the difference on liquid crystal arrangement, herein, the diffraction was mainly induced by an alternate transmittance/reflectance (i.e., amplitude) modulation to an incident light with a certain wavelength located in a selective reflection band of a binary patterned helical liquid crystal layer, producing diffraction both on the transmission and reflection sides of the sample. The waveband-selectivity was determined and manipulated by appropriately controlling the reflection band of the patterned helical liquid crystals. A prominent advantage compared to the majority of other liquid crystal polymer based devices is the electric responsiveness of such a device in addition to its photoresponsiveness. Moreover, an excellent light reconfiguration, exhibiting an erasing of the grating, followed by a rewriting of a Fresnel zone plate was achieved.

We present a compact highly sensitive microfiber coupler-based twist sensor formed by fusing and tapering two optical fibers and then connecting two of the pigtails to form a Sagnac loop. The device is miniature, low cost, and easily fabricated. The sensor has high twist sensitivities of $\sim 0.9$ nm/° when measuring wavelength shift and $\sim 0.16$ dB/° when measuring transmission power, both of which confirm that the sensor has good potential for application in the structural health monitoring and other areas.

According to the electromagnetic pump in Magnesium Alloy Casting Experiments Center of University of Science and Technology Liaoning, with the help of ANSYS software, we realized three-dimensional simulation of electric field of the pump by finite element analysis method, and calculated the distribution of electric field generated by five data sets , whose slot length and width were 30mm, 50 mm, 60 mm, 70 mm and 80 mm. We have explored how different runner dimensions affected electric field distribution in electromagnetic field, and simulated the distribution of current density. The optimal size of the runner is 50mm according to the current density distribution.

A photochromic diarylethene-based compound BMTA, which undergoes a reversible conversion between ring- open and closed isomers by alternating UV and visible light illumination, has been designed and synthesized. By utilizing a mask-free Digital Micro-mirror Device (DMD) micro-lithography system, arbitrary micro-photopatterning in polymer films doped with BMTA can be easily obtained with UV light writing. This recorded photo information can easily be erased by further visible light irradiation. The reversible and rewritable optical storage is based on photo-switched intermolecular energy transfer between the emissive host and the ring-closed isomer c -BMTA. Furthermore, the solution-processable organic light-emitting devices (OLEDs) with the single emitting layer doped with BMTA were fabricated, which exhibit rewritable memory behavior with light control. The luminescence and current density decrease significantly upon UV light irradiation, and recover by further visible light illumination. This is because the hole trapping is much facilitated in closed-ring isomer based devices, due to elevated HOMO level of c -BMTA. Without incorporating any cross-linking layer, the maximum luminescence and current density on/off ratios of this solution-processable and simple-structured device are 1.9 × 10 3 and 1.4 × 10 2 , respectively. Arbitrary micro-photolithography of OLEDs by DMD system has also been demonstrated, which shows great prospects in large-scale production of high resolution OLED displays.

a proper electric fi eld, simple grating with parallel stripes are produced in uniformly aligned cells. [ 14 ] Unfortunately, the defects induced by conventional mechanical rubbing technique signifi cantly interrupt the continuity of helical axis, thus it is diffi cult to get orderly arranged stripes with a uniform periodicity (Figure S1, Supporting Information). That is why the so-called “fi ngerprint” nonuniform textures are usually reported. [ 15 ] Moreover, the capability to manipulate the in-plane helical axes to realize more complex stripe pattern remains highly restricted. Based on the CLC in-plane aligned helical axis structure, diffraction gratings [ 16 ] and lithography mask [ 17 ] have been demonstrated. Moreover, the variation of the period of CLC grating [ 14,18 ] and its rotation [ 19 ] make it an excellent candidate for nonmechanical beam steering devices. Thus, the capability of generating high-quality CLC superstructures with ordered orientation and reliable periodicity is crucial for above applications. However, as mentioned above, the low quality and poor controllability of the self-assembled CLCs make the task very formidable. Furthermore, the present mechanical aligning technique is only suitable to produce 1D [ 14,20 ] or 2D gratings. [ 21 ]

O R IG IN A L P A P ER Abstract The unique electronic and mechanical properties, of graphene make it an ideal material for nanoelectromechanical system (NEMS) applications. Here, a miniature optical fiber current sensor based on a quasistatic graphene NEMS with a graphene membrane covering the hole on a pre-etched fiber tip and two gold electrodes on opposite sides of the tip has been demonstrated. The sensor overcomes the shortcomings of conventional optical fiber current sensors based on thermal effects, such as relatively low sensitivity, long response time, and huge device size; it has simultaneously a high sensitivity of 2.2 × 105 nm/A2, a short response time of 0.25 s and a compact device size of 15 μm, and has found practical application. Using a smaller graphene membrane with better quality can reduce the response time to submillisecond levels with a more precise measurement system. The sensor presented in this paper may pave the way for the practical usage of optical fiber current sensors based on thermal effects.

According to the cancer stem cell theory, a small subpopulation of cancer cells, known as cancer stem cells (CSCs), exist that are self-renewing and are involved in tumor invasion, metastasis and recurrence. A number of studies have reported that certain cancer cells are able to efflux the Hoechst 33342 dye. These cells are termed side population (SP) cells and share characteristic features of CSCs. The results of the present study revealed that 2.7% of primary head and neck squamous cell carcinoma (HNSCC) cells were SP cells. This was reduced to 0.7% following treatment with verapamil. The immunofluorescence and reverse transcription polymerase chain reaction analysis revealed that SP cells have an enhanced expression of the ATP-binding cassette (ABC) transporter protein ABC subfamily G, member 2 (ABCG2), which has been identified to be actively involved in drug exclusion. Similarly, the mRNA level of the oncogene B lymphoma Mo-MLV insertion region-1 and the stem cell surface proteins nestin and octamer-binding transcription factor-4 were highly expressed in the SP cells compared with the non-SP cells. In addition, it was demonstrated that HNSCC SP cells exhibited increased proliferation and were highly resistant to multiple drugs. These findings suggest that the presence of CSCs, such as SP cells, may be responsible for chemotherapy failure and tumor relapse in patients with HNSCC. Therefore, the identification of a novel therapeutic drug that could effectively target CSCs may help to eradicate refractory tumors.

We investigate wavefront engineering of photon pairs generated through spontaneous parametric down conversion in lithium niobate-based nonlinear photonic crystals (NPCs). Due to the complexity of domain structures, it is more convenient to describe photon interaction based on the nonlinear Huygens–Fresnel principle than conventional quasiphase matching regime. Analytical expressions are obtained to describe the transverse properties of down-converted photon states. The convenience of domain engineering in LiNbO3 crystals provides a potential platform for flexible wavefront manipulation of multiphoton states. The generation of N00N state with orbital angular momentum in a twisted NPC is studied utilizing this method. The obtained state is of great value in quantum cryptography, metrology, and lithography applications.

Digitalized chiral superstructures is achieved via photoaligning cholesteric liquid crystals (CLCs). The parallel generation, detection and demultiplexing of optical vortices with different OAM modes are demonstrated in a Dammann vortex grating encoded CLC superstructure.

A continuously deformative space possesses trivial or nontrivial topological characteristics depending on the associated homotopy groups associated with spaces describing the physical processes. Moreover, the interaction of spatial warping and structural symmetry always presents fantastic phenomena, especially in the systems with unique symmetrical properties such as quasicrystals. Here, we propose a quasi-periodic structure (QPS) with topological defects. The analytical expression of the corresponding Fourier spectrum is derived, which reflects the combined effects of topological structure and quasi-translational symmetry. Light-matter interaction therein brings unusual diffraction characteristics with exotic evolution of orbital angular momentum (OAM). Long-range correlation of QPS resulted in multi-fractal and pairwise distribution of optical singularities. A general conservation law of OAM is revealed. A liquid crystal photopatterned QPS is fabricated to demonstrate the above characteristics. Dynamic reconfigurable manipulation of optical singularities is achieved. Our approach offers the opportunity to manipulate OAM with multiple degrees of freedom, which has promising applications in multi-channel quantum information processing and high-dimensional quantum state generation.

We propose and demonstrate a pseudo Fabry–Perot filter in the terahertz frequency range of 0.1–0.5 THz. It consists of alternative liquid crystal layers and metallic slats. Separate sharp resonant peaks are shown in the simulated transmission spectra, and their positions shift toward higher frequencies when the refractive index of liquid crystal decreases. The measured transmission spectra are consistent with corresponding simulations. Via thermally tuning the refractive index of the filled liquid crystal, the resonant transmission frequencies shift accordingly. The work supplies a novel design for tunable terahertz filters, which would play important roles in terahertz imaging, sensing, high speed communication, and security applications.

We experimentally investigate the second-harmonic generation of a high-order Laguerre–Gaussian (LG) mode under the quasi-phase-matching (QPM) configuration. First, we introduce a simple method to observe the azimuthal (l) and radial (p) indices of the high-order LG modes. Based on the astigmatic transformation technique, l and p are revealed in the number of dark stripes of the converted pattern in the focal plane. Then, using this efficient method of measurement, we demonstrate in experiments a second-harmonic LG mode with its radial and azimuthal indices being twice those of the inputted fundamental wave through QPM in a periodically poled KTP crystal. Our results provide a feasible way to obtain simultaneously the LG modes with larger radial and azimuthal indices.

Metal halide perovskite nanocrystals (NCs) as a new kind of promising optoelectronic material have attracted wide attention due to their high photoluminescence (PL) quantum yield, narrow emission linewidth and wideband color tunability. Since the PL intensity always has a direct influence on the performance of optoelectronic devices, it is of vital importance to improve the perovskite NCs’ fluorescence emission efficiency. Here, we synthesize three inorganic perovskite NCs and experimentally demonstrate a broadband fluorescence enhancement of perovskite NCs by exploiting plasmonic nanostructured surface consisting of nanogrooves array. The strong near-field optical localization associated with surface plasmon polariton-coupled emission effect generated by the nanogrooves array can significantly boost the absorption of perovskite NCs and tailor the fluorescence emissions. As a result, the PL intensities of perovskite NCs are broadband enhanced with a maximum factor higher than 8-fold achieved in experimental demonstration. Moreover, the high efficiency PL of perovskite NCs embedded in the polymer matrix layer on the top of plasmonic nanostructured surface can be maintained for more than three weeks. These results imply that plasmonic nanostructured surface is a good candidate to stably broadband enhance the PL intensity of perovskite NCs and further promote their potentials in the application of visible-light-emitting devices.

Cholesteric liquid crystal (CLC) chiral superstructures exhibit unique features; that is, polychromatic and spin-determined phase modulation. Here, a concept for digitalized chiral superstructures is proposed, which further enables the arbitrary manipulation of reflective geometric phase and may significantly upgrade existing optical apparatus. By encoding a specifically designed binary pattern, an innovative CLC optical vortex (OV) processor is demonstrated. Up to 25 different OVs are extracted with equal efficiency over a wavelength range of 116 nm. The multiplexed OVs can be detected simultaneously without mode crosstalk or distortion, permitting a polychromatic, large-capacity, and in situ method for parallel OV processing. Such complex but easily fabricated self-assembled chiral superstructures exhibit versatile functionalities, and provide a satisfactory platform for OV manipulation and other cutting-edge territories. This work is a vital step towards extending the fundamental understanding and fantastic applications of ordered soft matter.

Mesoscopic hierarchical superstructures bridge the micro and macro worlds and play vital roles in natural materials. To mimic hierarchical organization in nature, one promising strategy is the convergence of top-down microfabrication and bottom-up self-assembly. Much efforts have been devoted to this field, but till now, the precise realization and rational control of large-area perfect hierarchical superstructures is still challenging. On the other hand, Smectic liquid crystals (SLCs) are formed by flexible molecular layers of constant thickness. If the nanometer-thin smectic layers can be manipulated in an origami manner, a Japanese art that constructs various 3D objects via folding pieces of papers, brand new hierarchical superstructures possessing exceptional features then could be realized. In this work, the smectic layer origami is accomplished via preprogrammed photoalignment. The principle is rooted in the anisotropy of molecular interactions at interfaces, which makes the preset patterned alignment favoring a certain layer bending of adjacent SLCs, and subsequently dominating the configuration of entire family of smectic layers. Thanks to the excellent flexibility of photoaligning, the unit geometry (shape, size and orientation) as well as the clustering characteristic (lattice symmetry) of fragmented TFCDs can be rationally designed and freely manipulated over square centimeters. The obtained fragmented toric superstructures break the rotational symmetry while maintain the radially gradient director field, enabling metasurface-like direction-determined-diffraction. We believe this work is an important step toward extending the fundamental understanding of self-assembled soft materials and enhancing the construction of possible hierarchical superstructures. It may inspire extra possibilities in advanced functional materials and fantastic photonic applications.

A terahertz (THz) q-plate is proposed and demonstrated to generate THz vortex beams. It is composed of a large birefringence liquid crystal (LC) with spatially-varying director distribution sandwiched by two pieces of fused silica glass. A polarization-sensitive alignment agent is photopatterned to carry out the specific LC director distribution. THz vortex beams with different topological charges are characterized with a THz digital holographic imaging system. The intensity and phase distributions consistent with theoretical analyses are obtained. Besides, an eight-lobed intensity distribution is observed corresponding to the vertical polarization component of a cylindrical vector beam. This work may inspire novel THz applications.

In this paper, we fabricate a microfiber coupler (MFC) functionalized with Teflon thin film. Since Teflon has a negative thermo-optic coefficient, it can compensate for the thermal effects of silica. The temperature dependence of the MFC depends on the radius of microfiber which controls the thermal effect contributions of silica and polymer. The device we fabricate has the temperature sensitivity of ∼ −2.9 pm/°C.

Stimulated Brillouin scattering (SBS) via electrostrictive force is a fundamental interaction between light and sound which limits the power in conventional optical fibers. The emergence of optical microfibers with subwavelength diameter, ultralight mass and an intense light field, provides a new platform for photon–phonon coupling, resulting in the radiation pressure mediated contribution of SBS. This study examines the optomechanical system in cylindrical coordinates, reveals the theoretically radiation pressure induced analogous, and demonstrates contrary effect compared with electrostrictive force in solid or hollow silica microfibers. The finding shows that the photon-phonon coupling, which is related to SBS, can be suppressed in a solid microfiber, and even be completely cancelled in a hollow microfiber.

Cholesteric liquid crystal (CLC) has attracted intensive attention due to its ability to form a periodic helical structure with broad tunability. CLC gratings in open systems are especially promising in sensing and micromanipulation. However, there is still much to learn about the inherent mechanism of such gratings. We investigate the light-driven rotation and pitch-tuning behaviors of CLC gratings in semi-free films which are formed by spin-coating the CLC mixtures onto planarly photoaligned substrates. The doped azobenzene chiral molecular switch supplies great flexibility to realize the continuous grating rotation. The maximum continuous rotational angle reaches 987.8°. Moreover, dependencies of light-driven rotation and pitch tuning on the dopant concentration and exposure are studied. The model of director configuration in the semi-free film is constructed. Precise beam steering and synchronous micromanipulation are also demonstrated. Our work may provide new opportunities for the CLC grating in applications of beam steering, micromanipulation, and sensing.

Light with transverse polarization structure, such as radial and azimuthal polarization, enables and revives lots of applications based on light-matter interaction due to their unique focal properties. To date, studies referring to this topic mainly concentrate in weak-light domain, yet it should have gained more attention in strong-light domain. A main factor contributing to the current situation is that the generation devices cannot afford high power. Here, in this proof-of-principle work, we demonstrate the generation of strong single-longitudinal-mode (SLM) cylindrical vector (CV) short pulses via stimulated Brillouin amplification, specifically, the energy is transferred from a 700 ps pump to a 300 ps Stokes pulse via parametrically generated coherent phonons. After amplification, a 100 mJ-level SLM CV pulse light with 300 ps duration is obtained. Meanwhile, the phase and polarization structures are high fidelity maintained. This result provides a practicable way to generate strong CV light, and by extending this mechanism into multi-pump beam combing system, even an ultra-high intensity CV light can be expected.

Stimulated Brillouin scattering (SBS) via electrostrictive force is a fundamental interaction between light and sound which limits the power in conventional optical fibers. The emergence of optical microfibers with subwavelength diameter, ultralight mass and an intense light field, provides a new platform for photon–phonon coupling, resulting in the radiation pressure mediated contribution of SBS. This study examines the optomechanical system in cylindrical coordinates, reveals the theoretically radiation pressure induced analogous, and demonstrates contrary effect compared with electrostrictive force in solid or hollow silica microfibers. The finding shows that the photon-phonon coupling, which is related to SBS, can be suppressed in a solid microfiber, and even be completely cancelled in a hollow microfiber.

The topological effects accompanied by phase structuring during the interaction between optical fields and nonlinear crystals are presented and demonstrated. The topological phase transition in the optical field is determined during the quasi-phase matched second harmonic frequency conversion process. The mapping relationship between the corresponding topological invariant and the phase parameters is derived, and two critical transition points are obtained. The transition of the total orbital angular momentum (OAM) in the propagation direction is verified to be the physical origin of this topological regulation through OAM spectrum analysis. This work provides a new perspective for examining nonlinear light-matter interaction, which can inspire promising applications in structured light generation and optical information processing.

We demonstrate a tunable terahertz (THz) absorber based on an indium tin oxide (ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching. The thickness of the middle dielectric layer is only 60 μm, which makes the absorber very transparent and flexible. The experimental results show that the THz resonant peaks have a high performance near 1 THz. By setting spacers of different thicknesses between the middle layer and the ITO mirror, a new type of tunable THz absorber is proposed. Its absorption peak frequency can be continuously adjusted from 0.92 to 1.04 THz between TE and TM polarization. This transparent THz metamaterial absorber is expected to be widely used in THz imaging, sensing, and biological detection.

Measuring the microscopic temperature of graphene is challenging. We used cholesteric liquid crystal microcapsules (CLCMs) as temperature sensors to detect the local temperature of three-dimensional porous graphene through quantitative visualization. Based on a CLCM (∼20 μm in size), we determined the temperature variation in a small area with an accuracy of 0.1°C. By analyzing the color changes between two CLCMs, we demonstrated the temperature changes dynamically in a region with a diameter of approximately 110 μm. Furthermore, by comparing the color evolution among the three CLCMs, we visualized the anisotropic thermal properties in the micro-zone. This convenient and low-cost temperature measurement method is expected to further improve graphene-based devices.

This article describes the Parabolic trough solar collector design of single-axis tracking system based on PLC, Siemens S7-300 as a controller, using a complex mathematical model, based on the special climate of Western Region, select the single-axis design process, greatly reduced cost, collectors need only be completed that automatically tracks the sun azimuth. Feedback device selection angle sensor, light intensity sensor and sun sensor, strain two conditions that cloudy and sunny, which greatly improves the efficiency of the collector, the better to achieve real-time tracking grasp the situation.

High birefringence liquid crystals play a key role in tunable THz devices. A fluorinated phenyl-tolane based nematic mixture was prepared with birefringence >0.3 at around 1THz Several THz phase shifters are further developed toward quarter-wave and half-wave plates. Both subwavelength wire-grids and graphenes are employed as transparent electrodes, which show some unique advantages.

Fruit bagging has been widely used in the fruit production industry; however, in apples, it is known to cause a significant decrease in fruit sugar contents. To address this issue and identify the changes in leaf mineral contents associated with fruit sugar levels in bagged apples, aqueous solutions of 10 g L−1 CaCl2, 5 g L−1 KH2PO4, or 2 g L−1 Na2B4O7·10H2O were foliar sprayed during four fruit developmental stages. The late-season leaf phosphorus (P) and potassium (K) contents after the rapid fruit growth period and the soluble sugar contents in ripening fruit were significantly lower in bagged fruit than in non-bagged fruit (11.1–15.09 %). The decreases in leaf P and K contents caused by bagging were almost completely compensated for by foliage applications of CaCl2, KH2PO4, or Na2B4O7 during the fruit set period. Therefore, the fruit soluble sugar contents were significantly higher in bagged ripening fruit with foliar spray than in bagged fruit without foliar sprays, reaching the levels of non-bagged apples. The decrease in the sugar contents of bagged apples was closely associated with the decrease in late-season leaf P and K levels caused by fruit bagging.

Amplified spontaneous emission and random lasing are investigated in random systems with dye-doped nematic liquid crystals. And that temporal stability of random lasing is analyzed. The influence of pumping polarization as well as the multiple scattering and reflection between boundaries on the emission behavior and the formation of coherent feedback is investigated in detail. For freely suspended samples, certain emission wavelength can be obtained by changing the pump wavelength. This feature is useful in making wavelength-tunable lasers. Moreover, as the pumping thickness of wedge sample increases, the emission spectrum is red shifted and the average spacing of adjacent spikes decreases. This property can be applied in laser mode selection, i.e., the number of modes within certain wavelength range can be chosen.

We fabricate an Ampere force based photonic crystal fiber (PCF) magnetic field sensor by bonding a PCF in-line modal interferometer (PCFMI) with an aluminum (Al) wire together. This sensor is very compact, cost-effective, temperature insensitive, highly stable over time and easy to be fabricated only including cleaving and splicing processes. An electrical current flowing through the Al wire in a perpendicular magnetic field can generate Ampere force to lead to the curvature of the Al wire and the PCF. As the cladding mode of the PCF with a large mode field diameter is very sensitive to the curvature, the average magnetic field sensing sensitivity can reach 32.4 pm/mT when 100 mA electrical current is applied with excellent repeatability. Higher sensitivity and a minimal detectable magnetic field of less than 0.1 mT can be realized by increasing the applied electrical current.

A new method based on introducing a photonic crystal fiber (PCF) in-line interferometer for hydrogen sensing is demonstrated. One end-face of the PCF and part of the outer-face of the fiber are plated with a thin palladium film by magnetron sputtering, while the other end is connected to the optical path. Therefore, a set of reflection-type all-fiber hydrogen sensor system is accomplished. Hydrogen concentration from 0% to 5% was detected in the experiment and the related interferometric resonant wavelength-shift was recorded. The maximum wavelength shift is over 1.2 nm. The whole system has an all-fiber optical path without any bulk-optic components, and this design obtains a high level of integration, a high stability, and low production costs.

Orbital angular momentum (OAM) of light has been extensively studied during the past two decades. Till now, it is a formidable challenge to dynamically manipulate OAM in fast switching speed, good beam quality and low power consumption. Here, an alternative strategy is proposed through the combination of the uniformly-aligned ferroelectric liquid crystal (FLC) and the space-variant photo-patterned nematic liquid crystal. Owing to the excellent electro-optical properties of the adopted FLC, the high-performance electrical switching of OAM, especially, its helicity and the superposed state (i.e., the cylindrical vector beam), can be realized in good quality and high efficiency. The symmetric switching time is down to 120 µs even at a very low driving voltage of 1.7 V/µm. This supplies a practical and universal method towards high-frequency manipulation of OAM and other structured beams.