This PDF file contains the front matter associated with SPIE Proceedings Volume 12479, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

The underwater photoelectric detection equipment mainly uses 532 nm laser as the light source, and GaAlAs with Al component of 0.63 can obtain the cutoff wavelength near 532 nm, which is an excellent photocathode material to meet the requirement of narrow band spectral response of 532 nm laser. Furthermore, the light absorptance of the cathode can be improved effectively by the quadrangular prism or cylinder nanostructured arrays prepared on the reflection-mode Ga_0.37Al_0.63As cathode surface, and the maximum light absorptance can reach 96.2% at 532 nm, when the cylinder nanostructured array with a height of 900 nm and a base width of 100 nm. Nevertheless, the Ga_0.37Al_0.63As cathode with the quadrangular prism nanostructured array is less influenced by the incident angle of light.

Beam structure stabilization for the high-power structured modes with transverse patterns as Lissajous figures created by an off-axis pumped degenerate-cavity laser is explored. Through the employment of a YVO₄/Nd:YVO₄ composite gain crystal with the front undoped segment as an effective heat spreader, it has been experimentally verified that not only the mode stability and purity of the generated Lissajous beams are significantly improved but the output power efficiency is obviously enhanced. With superior mitigation ability against the thermal aberration under high-power pumping, the proposed scheme of using the composite gain crystal to replace conventional uniformly doped crystal can offer a promising solution to realize high-power, high-order structured beams with excellent beam stability.

This paper presented an alternative technique for fabricating the dry film holographic grating based on a mask generated by computer simulation and experimental results. The mask was generated by a fringe pattern which is created by the mathematical model of two beams interference with various angles. Computer simulation of the fringe pattern was printed on film, i.e., the holographic grating mask. The mask was attached on dry film and then illuminated by UV light, where the lithography technique was applied. According to the lithography technique, the computer-generated holographic grating mask was transferred to dry film. After fabrication, fringe patterns obtained from the grating were observed. Then, the grating period was analyzed and confirmed by Scanning Electron Microscope (SEM). Experimental results show that the method could apply to fabricate the dry film holographic grating.

This paper demonstrates the possibility of optically trapping a single calix[4]arene microcluster in water. Calix [4]arene microclusters with a size range between 2.53 to 2.84 µm were optically trapped using optical tweezers at 976 nm in water. The optical stiffness of trapped calix[4]arene microclusters was evaluated based on the trapping laser power density. The finding provides a starting point for possible optically controlled calixarene microcluster for sensor and actuator applications in water.

A study was made of the spatial distribution of the intensity of the Laguerre-superGaussian (1,0) modes with circular, radial and azimuthal polarization depending on the change in the height of silicon subwavelength optical elements, the height of which varied from 0.2 to 3 wavelengths. Simulation by the finite difference method in the time domain showed that a change in the height of the considered optical elements significantly affects the diffraction pattern in the near zone. The smallest focal spot size was obtained for "-" circular polarization at an element height equal to two wavelengths.

The study attempts to quantify the optical stiffness of a single 4-Cyano-4-Pentylbiphenyl (5CB) microdroplet trapped in water using optical tweezers. 5CB microdroplets of various sizes were produced by mixing 0.5 µL 5CB solution with 2 mL of deionized water and sonicated for 1 minute. Factors such as 5CB microdroplet size and optical power density used in trapping were considered in this study. The study is significant for future use of 5CB microdroplet as a probe for microactuator and sensing applications.

Rotation of nematic liquid crystal (NLC) droplets by irradiation of focused circular polarized light is experimentally studied. Optical torque transferred to a droplet depends on its size. We discuss the relation between the LC molecular alignment inside the droplet and its rotation mechanism. In a larger droplet, the internal LC alignment is bipolar and wave-plate behavior becomes dominant. In a smaller droplet, the optical anisotropy reduces with decrease of its size and scattering process mainly contributes its rotation. We also construct multiple LC rotators system using a holographic optical tweezer. Such optically controllable vortex enables us to realize complex flow field at micron-scale.

We demonstrate the direct generation of watt-level orbital Poincaré sphere (OPS) modes operating at 1.173 μm, corresponding to the first-Stokes emission of the 882 cm^-1 Raman shift in Nd:GdVO₄ crystal, by employing a tight needle pumping beam with an off-axis pumping geometry. Maximum Laguerre-Gaussian (LG) mode output power of ~1.2 W was achieved, corresponding an optical conversion efficiency of 14.0 %.

Deformed beam structures of Lissajous transverse patterns induced under high-power pumping were explored in an off-axis pumped Nd:YVO₄ Laser within a degenerate cavity configuration. Experimental results show that beam structure variations including elongation, rotation and vagueness will occur with increasing pump power. Considering crystal axis rotation of gain medium induced by the inhomogeneous temperature gradient under high-power pumping, the derived resonant wave function of the spherical cavity can well reconstruct the experimental observation to further give an explicit relation between the tilt angle and aspect ratio of Lissajous patterns. It is believed that this finding can provide helpful information for the research on high-power structured light.

We demonstrated the optical trapping of silicon nanoparticles in superfluid helium. The silicon nanoparticles were produced via in-situ laser ablation in superfluid helium. The dispersed nanoparticles were optically trapped using near-infrared laser light. With the combination of semiconductor material and the wavelength of 1.5 μm, we can strongly suppress the heat generation in superfluid helium. The thermally stable situation provides us with an important platform for studying the fundamental properties of superfluid helium with the aid of the optical manipulation technique.

We demonstrate the laser induced forward transfer of fluorescent dye solution thin films with different viscosity by employing a single 532-nm nanosecond optical vortex pulse. Upon irradiating the laser pulse, a single microdroplet is ejected from the donor film, and it is deposited onto a receiver substrate. Well-aligned microdots with the same diameter were printed on the substrate with optical vortex, whereas the production of microdots in uniform size was prevented with a conventional Gaussian beam. In addition, we demonstrate the microprinting of a number of droplets by optical vortex.

Here we show that conjugated polymers bearing chiral side chains self-assemble into solid microspheres with a twisted bipolar interior. The resultant microspheres, when dispersed in methanol, exhibit CPL with a g_lum value as high as 0.23. The microspheres are mechanically robust enough to be handled with a microneedle under ambient conditions, allowing comprehensive examination of the angular anisotropy of CPL. The single microsphere is found to exhibit distinct angularly anisotropic birefringence and CPL with g_lum up to ∼0.5 in the equatorial plane, which is 2.5-fold greater than that along the polar axis. Such optically anisotropic solid materials are important for the application to micrometer-scale light-emitting, visualizing, and optical vortex generation devices.

The determination of the relation between the phase modulation and the geometric parameters of a single meta-atom, is the most important but also time-consuming part in a meta-surface design. Here, by developing a machine learning tool, the design process of a high performance achromatic metalens can be greatly simplified and accelerated. The backpropagation neural network is used to build a library of the phase modulation data with 15753 meta-atoms in less than 1 s. In the experiment, designed metalens has been demonstrated to show a high performance of achromatic focusing and imaging ability in the visible wavelengths from 420 to 640 nm without the polarization dependence.

Herein, we report on the direct generation of red (640 nm) and orange (607 nm) higher-order LG modes from the Pr³⁺:LiYF₄ (Pr³⁺:YLF) laser with an intra-cavity plano-convex spherical lens. The strong spherical aberration of the intra-cavity lens allows the oscillation of red higher-order LG modes represented by the coherent superposition of degenerated LG modes with positive and negative orbital angular momentum (OAM), |ℓ|≤31. A desired higher-order LG mode is selectively generated from the laser cavity simply by adjusting an on-axis position of the intra-cavity lens. Also, the system enables the generation of orange higher-order LG modes coherently superposed by degenerated positive and negative LG modes with |ℓ|≤17.

We propose a new approach for light induced chiral surface reliefs, in which multiple-armed chiral surface reliefs are formed in an azo-polymer film by the irradiation of the temporally rotating petal beams without Orbital Angular Momentum (OAM). This approach offers new fundamental physical insight of light matter interaction, and it might open the door towards advanced ultrahigh density rewritable optical data storages.

This paper analyzed the effective use time of Phenanthraquinone-doped polymethylmethacrylate(PQ/PMMA) photopolymer, the effective use time here and below refers to the number of days in which there is no significant change in the reproduction data page and Bit Error Rate(BER) when the material is recorded and read on the day it is made compared to when it is recorded and read after a period of time, we tentatively analyzed that PQ/PMMA underwent a short baking polymerization stage of 4 hours at 60°C, its effective use time can be extended by about 30% compared to the long baking polymerization stage of 10 hours, and the diffraction efficiency is also significantly improved, also dramatically reduces the exposure time required to record information on the material. The observations we illustrate here provide an idea for the preparation of PQ/PMMA materials with high-performance holographic properties and longer effective use time while reducing the time required for thermal polymerization.

This paper analyzed the security of random phase encryption holographic storage technology. Taking binary random phase as an example, the recorded hologram is continually readout by series guessing reference. The experiment showed that the correlation coefficient between readout information and the recorded information was firstly decreased and then increased when the phase correct ratio of guessing reference is increased from 0% to 100%. The recorded information can’t be readout at all when the phase correct ratio of guessing reference range from 40% to 60%. Since the guessing reference with phase correct ratio between 40% and 60% has occupied majority guessing cases, the recorded information can’t be cracked in most cases. This indicates the high security of the random phase encryption storage technique.

We demonstrate the direct print of micron-scale dots consisting of close-packed gold nanoparticles by employing the optical vortex laser-induced forward transfer technology. Moreover, SAM enhances the close-packing of gold nanoparticles in the printed dot.

This paper proposes a complex amplitude demodulation method based on deep learning used in holographic data storage (HDS). To increase the storage capacity of a single data page in HDS, the complex amplitude of the object light can be used to encode the information data. However, the phase information of the complex amplitude cannot be detected directly. In this paper, we propose a non-interferometric complex amplitude retrieval method based on deep learning that can demodulate amplitude and phase simultaneously. A one-to-two convolutional neural network (CNN) is designed to establish the relationship between the intensity images captured by the detector and complex amplitude data pages. A simulation experiment is established to verify the feasibility of the proposed method.

We propose an entirely new printing technology based on an optical vortex laser induced forward transfer (OV-LIFT), which allows the production of microdroplets formed of an ultrahigh viscosity silver nano-ink (viscosity: 11 Pa∙s). The microdroplets are propelled and printed to be a dot with a diameter of <50 μm on a receiver film.

Metal doping in glass can change the properties of glass. A metal foil placed in direct contact with one side of the glass substrate. Continuous-wave (CW) laser illumination can implant metal spheres by heating the metal foil. In this study, the laser heating conditions required to implant metal spheres into glass are investigated experimentally and theoretically. The temperature of the glass exceeded the temperature threshold of laser absorption when the metal sphere was implanted. In addition, sphere implantation speed increased with the laser power density. The metal sphere was implanted at speeds of 20 to 50 mm/s.

A temperature gradient induced by a focused 2 μm Tm-doped fiber laser is used for opto-thermal trapping of colloidal particles in an aqueous solution. The water has a large absorption peak around 2 μm in wavelength due to its vibrational modes, and some local temperature gradient is generated around the focus where the colloidal particles are migrated when salt is slightly added to the solution. In this study, the experimental results under different salt (electrolyte) concentrations are compared in order to clarify the role of an electrostatic force generated due to ions redistribution in the temperature gradient. As a result, the particles are trapped when the salt concentration is higher than 10 μg/ml, whereas they are not trapped under this concentration. Although a prediction of the electrostatic field near the heat source is difficult, our findings suggest that the mechanism of trapping in our system may ascribe to thermoelectric effect.

For the study of attosecond physics and petahertz electronics, it is necessary to measure precisely the optical waveform of short pulses, including the carrier-envelope phase. A promising approach is to use the optical field emission from metal nanostructure, where the electron tunneling from metal surface is driven by plasmonic near fields. However, there have been problems of low current levels and laser-induced damages of metal nanostructures. Here, we develop an all-solid-state optical-field detector based on metal-insulator hybrid nanostructures, which works in the nanojoule range. The photoelectric efficiency is substantially increased because of the lowered energy barrier for photoemission and the higher near-field enhancements originating from the metal-insulator-metal plasmon. Laser-induced damage resistance is also improved by encapsulating the metal nanoantennas with dielectric materials.

We present sequential trapping and positioning of 20 nm polystyrene particles into an array configuration by using metamaterial plasmonic tweezers. The polystyrene nanoparticles suspended into a heavy water solution were trapped on adjacent plasmonic hotspots with a very low excitation power of 3.8 mW, creating a large trap stiffness of about 3.5 fN/nm. This high trapping stiffness kept the particles trapped into the nanocavities’ hotspots achieving almost 80% occupancy of the excited hotspots.

For the purpose of precise manipulation of single nanoparticles by optical trapping, we demonstrated optical trapping of nanoparticles enhanced depending on the wavelength of excitation laser. The optical trapping dynamics of quantum dot (QD) nanoparticles at the focal spot was evaluated by fluorescence correlation spectroscopy (FCS). The simultaneous irradiation with excitation and near-infrared lasers increased the average transit time of QDs at the focal spot, which depended on the laser power and the wavelength of the excitation laser. This suggests that the particle motion of QD nanoparticles is constrained at the laser focus due to enhancement of optical trapping based on the resonant optical response.

We have generated and propagated both diffracting and non-diffracting speckles using the scattering of perfect optical vortices. The diffracting speckles have been realized in the near field and non-diffracting speckles have been realized in the far field, i.e. after taking the Fourier transform of near-field speckles using a simple convex lens. We found that the experimental results are in good agreement with the theoretical results. These results may find applications in classical cryptography and communication as we have both varying and non-varying random field patterns with propagation distance.

We design and fabricate triangular trimer gold nanostructures with two different edge lengths and investigate effects of plasmon modes on the crystallization behaviors induced by plasmonic optical trapping. The location of the enhanced electric field depends on the edge lengths (170 and 230 nm) of the triangular trimer. The crystallization of NaClO3 was induced by the 1064-nm laser irradiation on a single trimer structure. The generated crystal is attributed to be a metastable crystal with birefringence. Polymorphic transformation occurs in the case of continuous laser irradiation onto a 230 nm trimer, but intriguingly never in the case of a 170 nm trimer. These results will contribute to the understanding of the crystallization mechanism of NaClO3 by plasmonic trapping and give a novel insight to polymorphic transformation.

Laser beams with spatially controlled cross-sectional polarization distributions, called vector beams, have attracted much attention for their ability to be focused to dimensions below the diffraction limit. Here, we realize a single-chip vector beam generator that does not require any external optical elements. This generator consists of modulated photonic-crystal lasers (M-PCSELs) whose photonic-crystal lattice-point positions are spatially modulated to produce vertical diffraction of the two-dimensional lasing mode with various polarization distributions. By designing the modulation, we show that M-PCSEL can generate arbitrary cylindrically polarized vector beams.

Microscopic orbital motion of small particles in water was achieved by using the optical dissipative force of a pair of non-coaxially counterpropagating laser beams in conjunction with the thermal fluctuation (Brownian motion) at room temperature.

In the present work, we study optical trapping of two kinds of trapping targets together, 20 μm and 1 μm PS MPs, at the solution surface. The resulting assembly has a unique structure, that 1 μm PS MPs form a belt surrounding to a single 20 μm PS MP as the body, and 3-dimensionally grows more than 50 μm in diameter even though the trapping laser focus size is only 1 μm. We further demonstrate that the optically prepared light scattering assembly can serve as a unique reconfigurable random lasing medium. As the assembly is prepared exclusively where and when trapping laser is irradiated, our study will offer a new tool for studying optically reconfigurable and tunable disordered photonics.

Meandering throughout three-dimensional (3D) space, optical singularities form the structurally stable skeleton of structured light fields and define its topology. Although structured singular light fields have already allowed for advanced applications in, e.g., optical manipulation by custom angular momentum, their diverse fundamental properties are not yet fully understood. Due to experimental constraints, the study of tailored vectorial light and singularities in 3D space, in particular, has been limited to only a few examples. Pushing the limits, we present the customization of complex polarization singularity networks in self-imaging vectorial fields and their all-digital adaptability by our holographic modulation approach. Furthermore, we demonstrate control of the full electric field and its singularities in 3D space by forming linked constructs of polarization singularities sculpting the first optical skymionic Hopfion.

The spin angular momentum of light can induce the orbital rotation of matter via spin-orbit angular momentum conversion. In this work, we demonstrate the orbital rotation of nanoparticles using two different physical mechanisms. First, a nanoscale Poynting vector vortex is created above the nanogap of a plasmonic trimer nanoantenna upon circularly polarized laser irradiation. Using these trimer nanotweezers, single fluorescent nanodiamond trapping and rotation is experimentally achieved. Second, the orbital rotation of VO₂ nanoparticles is achieved using a focused, circularly polarized Gaussian laser beam. We demonstrate that the non-linear optical response caused by the insulator-to-metal phase transition of VO₂ leads to the formation of an annular trapping potential well around the center of the laser beam.

Optical tweezers (OT) are non-destructive, contactless tools that use light to trap and manipulate microscopic objects. We design and fabricate miniaturized systems that provide new optical trapping and manipulation tools. Our work takes advantage of the design freedom, flexibility, and high resolution afforded by micro 3D printing based on two-photon lithography. In particular, we present a dynamic counterpropagating beam trapping scheme, exploiting two 3D printed right-angle prism mirrors, and a novel hybrid photonic structure to create fiber optical tweezers.

The conservation of optical properties of light through scattering media allows the transmission of high bandwidth information. In this work, we utilize the nonlinear self-trapping and self-guiding of a laser beam to form several centimeters long self-arranged biological waveguides in suspensions of sheep red blood cells. To increase the range of transmitted wavelength through the scattering media, a pump/probe-type nonlinear coupling has been implemented, where the self-formed waveguide conducts weaker light at different wavelengths. Finally, we demonstrate the conservation of polarization state and orbital angular momentum of the transmitted light through these biological waveguides. The ability to create waveguides and maintain optical properties after multiple scattering events may lead to improvements in communication bandwidth with low loss through scattering media and allow development of new biomedical devices.