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Light-sheet fluorescent microscopy has become the leading technique for in vivo imaging in the fields of disease, medicine, and cell biology research. However, designing proper illumination for high image resolution and optical sectioning is challenging. Another issue is geometric constraints arising from the multiple bulky components for illumination and detection. Here, we demonstrate that those issues can be well addressed by integrating nanophotonic meta-lens as the illumination component for LSFM. The meta-lens is composed of 800-nm-thick GaN nanostructures and is designed for a light-sheet well-adapted to biological specimens such as the nematode Caenorhabditis elegans (C. elegans). With the meta-lens, the complexity of the LSFM system is significantly reduced, and it is capable of performing multicolor fluorescent imaging of live C. elegans with cellular resolution. Considering the miniature size and plane geometry of the meta-lens, our system enables a new design for LSFM to acquire in vivo images of biological specimens with high resolution.

Fluorescence microscopy with optical sectioning capabilities is extensively utilized in biological research to obtain three-dimensional structural images of volumetric samples. Tunable lenses have been applied in microscopy for axial scanning to acquire multiplane images. However, images acquired by conventional tunable lenses suffer from spherical aberration and distortions. Here, we design, fabricate, and implement a dielectric Moiré metalens for fluorescence imaging. The Moiré metalens consists of two complementary phase metasurfaces, with variable focal length, ranging from ∼10 to ∼125 mm at 532 nm by tuning mutual angles. In addition, a telecentric configuration using the Moiré metalens is designed for high-contrast multiplane fluorescence imaging. The performance of our system is evaluated by optically sectioned images obtained from HiLo illumination of fluorescently labeled beads, as well as ex vivo mice intestine tissue samples. The compact design of the varifocal metalens may find important applications in fluorescence microscopy and endoscopy for clinical purposes.

Vacuum ultraviolet (VUV) light plays an essential role across science and technology, from molecular spectroscopy to nanolithography and biomedical procedures. Realizing nanoscale devices for VUV light generation and control is critical for next-generation VUV sources and systems, but the scarcity of low-loss VUV materials creates a substantial challenge. We demonstrate a metalens that both generates—by second-harmonic generation—and simultaneously focuses the generated VUV light. The metalens consists of 150-nm-thick zinc oxide (ZnO) nanoresonators that convert 394 nm (~3.15 eV) light into focused 197-nm (~6.29 eV) radiation, producing a spot 1.7 μm in diameter with a 21-fold power density enhancement as compared to the wavefront at the metalens surface. The reported metalens is ultracompact and phase-matching free, allowing substantial streamlining of VUV system design and facilitating more advanced applications. This work provides a useful platform for developing low-loss VUV components and increasing the accessibility of the VUV regime.

We demonstrated a Moiré meta-lens to perform fluorescence bioimaging. The focal length can be varied by tuning mutual angles. The compact design plays an important role in fluorescence microscopy and endoscopy for clinical purposes.

The optical sectioning images of volumetric biological sample was obtained by varifocal metalens with Moire effect in fluorescence microscopy system in conjunction with telecentricity and HiLo image processing method. The varifocal metalens is capable of changing the focal depth ranging from 10 mm to 125 mm by tuning the relative angle between its paired metasurfaces. The standard resolution target and fluorescent mircrosphere are imaged and analyzed; its lateral resolution and optical sectioning capability are 2.46 μm and 7.5 μm, respectively. Our study offers a demonstration, a solid foundation, for developing more compact optical microscopy systems based on metasurface optics.

The optical tweezer is one of the important techniques for contactless manipulation in biological research to control the motion of tiny objects. For three-dimensional (3D) optical manipulation, shaped light beams have been widely used. Typically, spatial light modulators are used for shaping light fields. However, they suffer from bulky size, narrow operational bandwidth, and limitations of incident polarization states. Here, a cubic-phase dielectric metasurface, composed of GaN circular nanopillars, is designed and fabricated to generate a polarization-independent vertically accelerated two-dimensional (2D) Airy beam in the visible region. The distinctive propagation characteristics of a vertically accelerated 2D Airy beam, including non-diffraction, self-acceleration, and self-healing, are experimentally demonstrated. An optical manipulation system equipped with a cubic-phase metasurface is designed to perform 3D manipulation of microscale particles. Due to the high-intensity gradients and the reciprocal propagation trajectory of Airy beams, particles can be laterally shifted and guided along the axial direction. In addition, the performance of optical trapping is quantitatively evaluated by experimentally measured trapping stiffness. Our metasurface has great potential to shape light for compact systems in the field of physics and biological applications.

Optical meta-devices using meta-surfaces which composed of artificial nanostructures are able to manipulate the electromagnetic phase and amplitude at will. The great advantages of meta-devices are their new properties, lighter weight, small size, high efficiency, better performance, broadband operation, lower energy consumption, and CMOS compatibility for mass production. Given the demand for photonics, many optical meta-devices for the application and control of incident light are being quickly developed for beam deflection and reflection, polarization control and analysis, holography, second-harmonic generation, laser, tunability, imaging, absorption, focusing of light, multiplex color routing and light-field sensing. The design, fabrication and application of the novel optical meta-devices are reported in this talk.

We propose a Light-sheet fluorescent microscopy (LSFM) system with a flat metalens, which is used to replace the bulky illuminating components. The metalens is a diffractive optics elements (DOEs) composed of various gallium nitride (GaN) nanopillar for light-sheet generation, and it can be readily integrated in existing LSFM systems. In contrast to the traditional LSFM system, the metalens-based system is more compact and flexible, and its sectioning capability is comparable to the conventional illumination arm in LSFMs. The live fluorescent-labeled transgenic Caenorhabditis elegans (C. elegans) are exploited to verify the performance of this system. The intensity profile of oocytes in C. elegans with cellular resolution level was obtained.

We design and fabricate a 60 × 60 GaN based achromatic meta-lens array to capture multidimensional optical information of the scene. The working wavelength is from 400 nm to 660 nm which covers the entire visible light range. The highest efficiency of single metalens can be up to 74% at a wavelength of 420 nm, while the average efficiency is approximately 39% over the whole working bandwidth. The light field images and the depth information of objects can be determined by reorganizing the patches of sub-images and calculating the disparity of neighboring sub-images, respectively. The depth information can be used to optimize the patch sizes to render the all-in-focus image without artifacts. Our work provides several advantages associated with light field imaging: elimination of chromatic aberration, polarization selectivity and compatibility of the semiconductor process.

A light-field camera captures both the intensity and the direction of incoming light1–5. This enables a user to refocus pictures and afterwards reconstruct information on the depth of field. Research on light-field imaging can be divided into two components: acquisition and rendering. Microlens arrays have been used for acquisition, but obtaining broadband achromatic images with no spherical aberration remains challenging. Here, we describe a metalens array made of gallium nitride (GaN) nanoantennas6 that can be used to capture light-field information and demonstrate a full-colour light-field camera devoid of chromatic aberration. The metalens array contains an array of 60 × 60 metalenses with diameters of 21.65 μm. The camera has a diffraction-limited resolution of 1.95 μm under white light illumination. The depth of every object in the scene can be reconstructed slice by slice from a series of rendered images with different depths of focus. Full-colour, achromatic light-field cameras could find applications in a variety of fields such as robotic vision, self-driving vehicles and virtual and augmented reality. A metalens array of GaN nanoantennas is used to make a full-colour achromatic light-field camera.

Manipulation and precise delivery of optical energies in the regions of interest within specimens require different strategies. Hence, proper control of input beam parameters is a prerequisite. One of the prominent methods is metasurface optics, capable of crafting properties of light at nanoscales. Here, the generation of an abrupt autofocusing (AAF) beam by a nanophotonic metasurface for biomedical applications is demonstrated. Fluorescence guided laser microprofiling of mouse cardiac samples is experimentally investigated, using the AAF beam to deliver optical energy selectively to specific locations. In addition, photocoagulation of ex vivo swine skin tissue is performed and observed through optical coherence tomography. The results show great potentials for integrating metasurface optics to realize miniature laser surgery instruments for wide applications in biomedicine.

Metasurface-based components are known to be one of the promising candidates for developing flat optical systems. However, their low working efficiency highly limits the use of such flat components for feasible applications. Although the introduction of the metallic mirror has been demonstrated to successfully enhance the efficiency, it is still somehow limited for imaging and sensing applications because they are only available for devices operating in a reflection fashion. Here, we demonstrate three individual GaN-based metalenses working in a transmission window with extremely high operation efficiency at visible light (87%, 91.6%, and 50.6% for blue, green, and red light, respectively). For the proof of concept, a multiplex color router with dielectric metalens, which is capable of guiding individual primary colors into different spatial positions, is experimentally verified based on the design of out-of-plane focusing metalens. Our approach with low-cost, semiconductor fabrication compatibility and high working efficiency characteristics offers a way for establishing a complete set of flat optical components for a wide range of applications such as compact imaging sensors, optical spectroscopy, and high-resolution lithography, just named a few.

Metalens-array–based quantum source Spontaneous down-conversion is an exotic optical process in a nonlinear crystal in which a high-energy photon splits into two lower-energy photons that are quantum mechanically entangled. These entangled pairs are valuable commodities for quantum information processing and quantum communications. Because the experimental setup is usually performed with bulk optical components, there is a need to decrease the size scale for application. Li et al. combined an array of specialized metalenses with a nonlinear crystal and show that the scale of the process can be shrunk substantially. The approach should prove useful for developing miniaturized integrated quantum optical technologies. Science , this issue p. 1487

By growing an epitaxial GaN LED on C-rich a-SiC buffer deposited SiO2/Si substrate, the simplified transfer to versatile flexible metallic/dielectric membranes is demonstrated. Both the high growth temperature at 1000 °C and the slow deposition rate played important roles in the meticulous MOCVD growth of n-GaN along the surface normal of the a-SiC at the very beginning. High substrate temperature facilitated the refinement of C-rich SiC buffer from amorphous to partially crystalline with (0004)-orientation, which effectively reduces the lattice mismatch between n-GaN and SiC at the interface so as to gradually improve the crystalline n-GaN regrowth. The substrateless GaN LED transferred to flexible copper plates showed reduced turn-on voltage of 2.6 V, enhanced output power of 370 mW, enlarged power-to-current slope of 1.24 W A−1, increased external quantum efficiency of 45%, and reduced efficiency droop of 15% under a bias of 300 mA. The thermal conductivity of the transferred substrate affected the EL peak wavelength shift of the substrateless GaN LED on SiC buffer. Heating the GaN LED on flexible copper plate to 65 °C only reduced its power by 10% and red-shifted its wavelength by 1 nm under a bias at 100 mA; the Auger effect resulted in a degraded EQE of 39.1% and an enlarged EQE droop of 8.5%. Bending the surface diameter of the curvature of the copper plate to 1.2 cm decayed the output power by 12% and red-shifted the EL peak by 5 nm because of the lattice strain induced quantum confined Stark effect (QCSE). Such a bendable substrateless GaN LED transferred to flexible membrane with superior heat dissipation and bending tolerance is a desired lighting element for green photonics in this era.

All forms of light manipulation rely on light–matter interaction, the primary mechanism of which is the modulation of its electromagnetic fields by the localized electromagnetic fields of atoms. One of the important factors that influence the strength of interaction is the polarization of the electromagnetic field. The generation and manipulation of light polarization have been traditionally accomplished with bulky optical components such as waveplates, polarizers, and polarization beam splitters that are optically thick. The miniaturization of these devices is highly desirable for the development of a new class of compact, flat, and broadband optical components that can be integrated together on a single photonics chip. Here we demonstrate, for the first time, a reflective metasurface polarization generator (MPG) capable of producing light beams of any polarizations all from a linearly polarized light source with a single optically thin chip. Six polarization light beams are achieved simultaneously inclu...

We propose all-dielectric metasurfaces that can be actively re-configured using the phase-change material Ge2Sb2Te5 (GST) alloy. With selectively controlled phase transitions on the composing GST elements, metasurfaces can be tailored to exhibit varied functionalities. Using phase-change GST rod as the basic building block, we have modelled metamolecules with tunable optical response when phase change occurs on select constituent GST rods. Tunable gradient metasurfaces can be realized with variable supercell period consisting of different patterns of the GST rods in their amorphous and crystalline states. Simulation results indicate a range of functions can be delivered, including multilevel signal modulating, near-field coupling of GST rods, and anomalous reflection angle controlling. This work opens up a new space in exploring active meta-devices with broader applications that cannot be achieved in their passive counterparts with permanent properties once fabricated.

Metalenses have great ability in light focusing and can be tailored to exhibit varied functionalities for ultrathin optical applications. Here, we demonstrate a GaN metalens array which can be regarded as a light shaping generator for the structured light generation. The metalens array consists of 60 x 60 metalenses which can project a 42 cm x 42 cm light spots area at the distance of 1.5 M. The distance can be estimated by identifying the deformation of light spot distribution. The advantages of this metadevice is light weight, small, ultrathin, durable and easy to compact with other devices. Our design provides a new avenue for the structured light applications such as distance sensing and 3D environmental construction.

Here we demonstrated a GaN metalens array to project a light spots array which can be a light shape generator in the structure light applications. The advantages of this metadevice is light weight, small, ultrathin, durable and easy to compact with other device. The light spot size is a function with the distance of detector. A metalens array which arranged by the single metalens diameter is 20 μm projected a light spots array whose diameter of single light spot is 2.22 um in average at the distance is 150 cm far away and. Our design provides a new avenue for the structure light application such as distance sensing and 3D environmental construction.

Metasurfaces composed of artificial structures have attracted a huge number of interests due to their ability on controlling the electromagnetic phase and amplitude at subwavelength scale. Beside those promising characteristics, people now intend to discover the field of meta-devices, where we can attain optical functionalities through changing the features of metasurfaces in demand. In this talk, several metasurface based components for photonic applications will be performed and discussed, including versatile polarization control, pixel-scale metalens, and achromatic meta-devices.

Metalens significantly suffers from chromatic aberration issue, which limits its applications on color images. Here we demonstrate the first broadband achromatic metalens in visible wavelength based on the concept of integrated-resonant unit elements (IRUEs).

In contrast to the traditional bulk optical elements, metasurfaces provide a new perspective on flexibly shaping the electromagnetic field by manipulating its phase, amplitude as well as polarization at will via a compact and easy-of-fabrication system. However, due to the high phase dispersion of their building blocks, metasurfaces significantly suffer from large chromatic aberration. Such chromatic aberration significantly degrades the performance of full-color optical applications, such as in communication, detection, imaging, displaying etc. Here we propose a design principle to realize achromatic metasurface devices which successfully eliminate the chromatic aberration over a continuous wavelength regions from 400 to 660 nm and 1200 to 1680 nm in a transmission and reflection scheme, respectively, for circularly-polarized incidences. For this proof-of-concept, we demonstrate broadband achromatic metalenses which are capable of focusing light with arbitrary wavelength at the same focal plane. A broadband achromatic gradient metasurface is also implemented, which is able to deflect wide-band light by the same angle. Through this approach, various flat achromatic devices that were previously impossible can be realized, which will allow innovation in full-color detection and imaging.

An ultrathin planar cavity metasurface is proposed based on ultrathin film interference and its practicability for light manipulation in visible region is experimentally demonstrated. Phase of reflected light is modulated by finely adjusting the thickness of amorphous silicon (a-Si) by a few nanometers on an aluminum (Al) substrate via nontrivial phase shifts at the interfaces and interference of multireflections generated from the planar cavity. A phase shift of π, the basic requirement for two-level phase metasurface systems, can be accomplished with an 8 nm thick difference. For proof of concept, gradient metasurfaces for beam deflection, Fresnel zone plate metalens for light focusing, and metaholograms for image reconstruction are presented, demonstrating polarization-independent and broadband characteristics. This novel mechanism for phase modulation with ultrathin planar cavity provides diverse routes to construct advanced flat optical devices with versatile applications.

Metasurfaces, the two-dimensional (2D) sub-wavelength artificial structures, where light is not required to have a deep penetration, have shown the ability to tailor the amplitude, phase and polarization of light. The functionalities of various optical components can be realized by metasurface-based design, such as beam splitters, filters, waveplates, deflector, lens and holograms. Here, we propose a new type of metasurface based on the concept of ultra-thin film interference and experimentally demonstrate its feasibilities in beam deflector, light focusing and broadband meta-hologram in visible spectrum. Considering an ultra-thin thin film interference system, a sandwich structure, composed of air, a lossy material layer and a metallic mirror, the reflection of this system can be regarded as the linear superposition of the partial reflections from first interface and from the cavity after several roundtrips. First, we calculate the phases and reflections of various thicknesses of amorphous silicon (a-Si) on top of aluminum layer under normal illumination of an unpolarized light in the wavelength region from 400 to 850nm. 2 π phase coverage can be achieved by changing the film thickness of a-Si within 50 nanometers. We select two thicknesses (2-level phase modulation) for the demonstration of meta-devices. The ultra-flat grating metasurface for beam steering are designed. The reflection angles of grating metasurface can be modulated by changing its period, while the specular reflection is inhibited. We further demonstrate computer-generated holograms (CGH) based on ultra-thin interference metasurface. The holographic images are reconstructed by the combinations of phase- and amplitude- modulation. These devices show the great potential and CMOS-compatibility in the application of optics, display, security printing, and metasurface-based optical storage system.

Among various flat optical devices, metasurfaces have presented their great ability in efficient manipulation of light fields and have been proposed for variety of devices with specific functionalities. However, due to the high phase dispersion of their building blocks, metasurfaces significantly suffer from large chromatic aberration. Here we propose a design principle to realize achromatic metasurface devices which successfully eliminate the chromatic aberration over a continuous wavelength region from 1200 to 1680 nm for circularly-polarized incidences in a reflection scheme. For this proof-of-concept, we demonstrate broadband achromatic metalenses (with the efficiency on the order of ∼12%) which are capable of focusing light with arbitrary wavelength at the same focal plane. A broadband achromatic gradient metasurface is also implemented, which is able to deflect wide-band light by the same angle. Through this approach, various flat achromatic devices that were previously impossible can be realized, which will allow innovation in full-color detection and imaging., Metasurfaces suffer from large chromatic aberration due to the high phase dispersion of their building blocks, limiting their applications. Here, Wang et al. design achromatic metasurface devices which eliminate the chromatic aberration over a continuous region from 1200 to 1680 nm in a reflection schleme.

We report the most recent advances in optical meta-devices and their applications. The general principle and method of optical meta-devices are introduced. The development of the two most recent and state-of-the-art optical meta-devices, a broadband achromatic optical meta-lens in the visible range and a 60 × 60 achromatic meta-lens array, is shown. Full-color achromatic imaging in visible frequency (400 nm to 660 nm) is demonstrated with high efficiency (maximum 67%, average around 40%) by a GaN achromatic meta-lens. A nature-inspired 60 × 60 GaN achromatic meta-lens array with an individual meta-lens diameter of 21.65 μm, a focal length of 49 μm, and a numerical aperture of 0.2157 shows high-dimensional light-field image capture including the depth and velocity of the imaging objects. The total number of nano-antennas of the meta-lens array is more than 33 million which covers an area of 1.2 × 1.2 mm2. Results show the important advantages of optical meta-devices for flat optics are their small size, light weight, high efficiency, lower energy consumption, and mass producibility by semiconductor processes.

All forms of light manipulation depend on light–matter interaction, the fundamental mechanism is the modulation of its electromagnetic fields by the localized electromagnetic fields of atoms. The polarization of the electromagnetic field is the important factors to influence the strength of interaction. The generation and manipulation of light polarization have been traditionally accomplished with bulky optical components such as waveplates, polarizers, and polarization beam splitters that are optically thick. The miniaturization of these devices is highly desirable for the development of a new class of compact, flat, and broadband optical components that can be integrated together on a single photonics chip. Here we demonstrate a reflective metasurface polarization generator (MPG) capable of producing light beams of any polarizations all from a linearly polarized light source with a single optically thin chip. Six polarization light beams are achieved simultaneously including four linear polarizations along different directions and two circular polarizations, all conveniently separated into different reflection angles. Using the Pancharatnam– Berry phase-modulation method, the MPG sample was fabricated with aluminum as the plasmonic metal instead of the conventional gold or silver, which allowed for its broadband operation covering the entire visible spectrum. The versatility and compactness of the MPG capable of transforming any incident wave into light beams of arbitrary polarizations over a broad spectral range are an important step forward in achieving a complete set of flat optics for integrated photonics with far-reaching applications. [1]

We present the tunable optical response of phase change material Ge2Sb2Te5, which can be used to metasurfaces with varied functionalities. The concept of reconfigurable metasurface, which have different combination of unit cells with various geometries and phase states are proposed. The research is promising to apply to the area of the metadevice.

Selective excitation of specific multipolar resonances in matter can be of great utility in understanding the internal make-up of the underlying material and, as a result, in developing novel nanophotonic devices. Many efforts have been addressed on this topic. For example, the emission spectra related to the different multipolar transitions of trivalent europium can be modulated by changing the thickness of the dielectric spacer between the gold mirror and the fluorescent layer. In this talk, we reported the results about active control of the multipolar resonance in metadevices using the coherent control technique. In the coherent control spectroscopy system, the optical standing wave constructed from two counterpart propagation coherent beams is utilized as the excitation. By controlling the time delay between two ultrafast pulses to decide the location of metadivce as the electromagnetic field node or antinode node of standing wave, the absorption related to the specific multipolar resonance can be controlled. Using this technique, with the 30-nm-thick metadevice, the broadband controlling light with light without nonlinearity can be realized. The switching contrast ratios can be as high as 3:1 with a modulation bandwidth in excess of 2 THz. The active control of the high order and complex optical resonance related to the magnetic dipole, electric quadrupole, and toroidal dipole in the metamaterial is reported as well. This research can be applied in the all ultrafast all-optical data processing and the active control of the resonances of metadevice with high order multipolar resonance.

Phase change materials are used as the recording layer in optical data storage, electronic storage and nanolithography due to the enormous physical difference between crystalline and amorphous states. In recent years, they are demonstrated to exploit in various tunable plasmonic devices, such as perfect absorber, planar lenses, plasmonic antenna, Fano resonance and so on. However, in these researches, the phase change material merely plays a role as a refractive index switchable substrate. In this paper, we study the intrinsic optical properties of phase change material Ge2Sb2Te5 (GST) in the near-infrared regime. A clear insight into the dipole resonance system of GST is provided. The reflection phase retardation and intensity of each unit cells depending on the phase state and geometry are estimated. Further, we introduce the concept of reconfigurable gradient metasurface, which has different anomalous reflection angles by switching the combination of nanorods with different geometries and phase states. The research has great potential in the area of tunable metamaterial device (metadevice) in the future.

Conventional optical data storage such as digital versatile disc (DVD) and Blu-ray disc (BD), provide us inexpensive and compact media for satisfying information storage requirement for decades. As the knowledge and information increase rapidly, the requirement cannot be already satisfied by current data storage systems. As far as we know, the size of recording mark, the critical storage density indicator, depends on recording energy, writing strategies, opto-thermal threshold plane and thermal conductivity. Readout is limited by optical resolution limit, the wavelength of readout laser and numerical aperture (N.A.) of objective lens. In this talk, I will introduce several means to increase the optical storage density. A powerful tool, conductive-tip atomic force microscopy (C-AFM), with the advantages of high spatial resolution, high contrast of conductivity and non-destructive method to help us better understand the formation of recording marks is also presented. Finally, I will show our recent efforts on realizing the extreme of recording mark.

Split-ring resonator (SRR), one kind of building block of metamaterials, has attracted wide attentions due to the resonance excitation of electric and magnetic dipolar response. Fundamental plasmon properties and potential applications in novel three dimensional vertical split-ring resonators (VSRRs) are designed and investigated. The resonant properties arose from the electric and magnetic interactions between the VSRR and light are theoretically and experimentally studied. Tuning the configuration of VSRR unit cells is able to generate various novel coupling phenomena in VSRRs, such as plasmon hybridization and Fano resonance. The magnetic resonance plays a key role in plasmon coupling in VSRRs. The VSRR-based refractive-index sensor will be demonstrated, as shown in Figs. 1. Due to the unique structural configuration, the enhanced plasmon fields localized in VSRR gaps can be lifted off from the dielectric substrate, allowing for the increase of sensing volume and enhancing the sensitivity. We perform a VSRR based metasurface for light manipulation in optical communication frequency, as shown in Fig. 1 as well. By varying the prong heights, the 2π phase modulation can be achieved in VSRR for the design of metasurface. Because the phase shift is changed via the upright configuration rather than the one parallel to the substrate, it can be used for high areal density integration of metal nanostructures and opto-electronic devices. Fabrication of three dimensional VSRR by stress-driven assembly method for uniaxial-isotropic metamaterials is demonstrated as well.

Plasmonic metamaterials, composed by arti?cial micro or nanostructures, exhibit extraordinary optical properties such as negative refraction, which cannot be observed in nature. The focused ion beam (FIB) and electron beam lithography (EBL) technique are frequently adopted to fabricate multilayer and three-dimensional plasmonic structures, but the alignment error, high cost and time consuming cannot be avoided. In contrast, the laser direct writing (LDW) technique is one of the best candidates to fabricate plasmonic structure owing to its low cost, high throughput and simple experimental setup. Here, we fabricate the plasmonic structures to manipulate the scattering of SPP waves by LDW technique. Both the backward and forward scattering of surface plasmonic waves can be generated by the arranged gold (Au) nanobumps on an Au thin film. Upon controlling the geometry of the plasmonic structures, the height, position, and pattern of scattered light are modified as desired. It provides a simple and efficient way to project a specific light pattern into free space, and demonstrate the capability of three-dimensional light manipulation. Furthermore, we demonstrated that, with tightly contacted donor-receiver pair, multilayer plasmonic structures such as multilayer split resonant rings and square-shaped multilayer resonant cavities, can be fabricated on donor by laser-induced forward transfer (LIFT) process as a kind of LDW. By using the contact-mode LIFT, the illuminated materials of sputtered multilayer thin films are ablated and transferred to the receiver, which would leave the uniform metamolecules with multilayer structures on the donor. Finally, we have analyzed their plasmonic modes by both measurement and simulated results. These properties may facilitate many applications in integrated optics, optical nonlinearities, and luminescence enhancement, etc‥

Metamaterials are the artificial materials composed of multiple individual elements in specially designed periodic subwavelength patterns. The properties of these metamaterials strongly depend on the featured shape or size of the unit of metamaterials rather than the original properties of the composition of materials. Their precise shape, geometry, size, orientation and arrangement can affect the light in an unconventional manner, creating material properties which are unachievable with conventional materials, such as negative refractive index, abnormal reflection, and so on. Due to these fascinating properties, we have designed and fabricated various plasmonic metamaterials with localized energy, electromagnetic field enhancement, and nonlinearity by the state of the art methods, such as e-beam lithography with multi-exposure technique, focus ion beam drilling, ultrafast laser direct writing, phase-change materials etching process, etc… This talk will discuss about the diverse novel applications for the plasmonic metamaterials in the green energy, environment, and better life, respectively. As for the applications in the green energy, it will cover environmentally friendly green energy sources, high-efficiency solar energy conversion over entire spectrum, and nonlinear plasmonic nano-laser. The metamaterials could also be used for the high efficiency photo-catalyst water treatments, high-efficiency broad-band gradient meta-surface, three-dimensional full color plasmonic holograph, three-dimensional split ring resonators based biosensor, hyperbolic metamaterials for subwavelength resolution, and so on. These novel applications pave new ways to apply the fundamental physics of plasmonic metamaterials to achieve clean environment with high-efficiency energy sources, as well as the bright future of human being life.

Using the curved arrangement of Au nanobumps, the scattering of surface plasmon waves are transformed into spots at desired locations and altitudes in three-dimensional space. The light can be modulated into desired light patterns. This work is very promising for compact plasmonic circuitry, projection, live-cell imaging, optical sensing, and holography.

A novel method based on femtosecond laser-induced forward transfer for high-throughput and efficient fabrication of periodic multilayer plasmonic metamaterials is demonstrated. With precisely controlling laser raster path applied on sputtered multilayer thin films, the laser-ablated materials can be transferred to another substrate leaving the fabricated multilayer structure on the original substrate. Subsequently, three-dimensional metamaterials can be made by multilayer structuring. Moreover, all the experimental results show that to create such multilayer split resonant rings (SRRs) with uniform profile, the laser fluence should be fine controlled under proper conditions. The optical property of fabricated multilayer SRR array is investigated by optical measurements and finite-difference time-domain simulations, showing various resonant modes in the middle-IR region. The calculated induced current distributions exhibit rich resonance properties of the structures as well. This work markedly extends the laser direct writing technique to a wide application in fabricating complicated metamaterials and plasmonic devices efficiently.

Backward and forward scattering of surface plasmonic wave interactions from gold nanobumps on the surface of a 30-nm gold thin film demonstrate three-dimensional (3-D) focusing and diverging properties. Fan-shaped forward scattering of an individual nanobump is observed. A quarter-circle structure composed of nanobumps is exploited to manipulate scattering from each nanobump. Experimental results show that 3-D propagation vectors generated by the gold nanobumps with their heights of 16 nm can deflect the surface plasmonic waves to produce 3-D focusing at 3.6 μm above the surface of the gold film. We clearly demonstrate that 3-D forward and backward focusing from gold nanobumps are with different amplitudes and directions of the vertical propagation vectors.