Nanophotonic Materials and Devices |
Prof. Kenneth B. Crozier | Department of Electrical and Electronic Engineering, University of Melbourne | Title and Abstract |
Title： Engineering Light-Matter Interactions at the Nanoscale Abstract： This presentation reviews work carried out in recent years by the Crozier group on the topic of engineering light-matter interactions in optical nanotweezers and in nanowire photodetectors. |
Dr. Jun-Yu (Bruce) Ou | University of Southampton | Title and Abstract |
Title： Nano-optomechanical Metamaterials Abstract： The development of metamaterials has led to demonstrations of fascinating optical properties such as negative refraction, invisibility, ultra-thin lenses and many more. However, the unique properties of metamaterials are usually fixed and narrowband. Here we develop nano-optomechanical metamaterials that offer a flexible platform for static and fast dynamic control of metamaterial optical properties using electrostatic, magnetic, optical forces and ultrasound. |
Prof. Doyeol Ahn | Department of Electrical and Computer Engineering,
University of Seoul | Title and Abstract |
Title： Cuprous halides semiconductors as a new means for highly efficient light-emitting diodes Abstract： In group-III nitrides in use for white light-emitting diodes (LEDs), optical gain, measure of luminous efficiency, is very low owing to the built-in electrostatic fields, low exciton binding energy, and high-density misfit dislocations due to lattice-mismatched substrates. Cuprous halides I-VII semiconductors, on the other hand, have negligible built-in field, large exciton binding energies and close lattice matched to silicon substrates. Previously, we showed that the optical gain and the luminescence are expected to be much larger than that of group III-nitrides due to large exciton binding energy and vanishing electrostatic fields. Here we report theoretical and experimental results of optoelectronic properties of cuprous halides grown on Si which agrees with the theoretical predictions. |
Dr. Vassili Savinov | University of Southampton | Title and Abstract |
Title： Seeing the Invisible: Direct Detection of Electric, Toroidal and Anapoles Dipoles Abstract： Increasing interest in electrodynamics and spectroscopy of toroidal excitations in matter has initiated a discussion on independent physical significance of toroidal and electric dipole excitations. Here we introduce two experiments that reveal their fundamental differences. Key Word—Spectroscopy, Metamaterials, Inverse Scattering, Relativity |
Optical Waveguides and Communications |
Dr. Ming-Fang Huang | NEC Labs America, Inc. | Title and Abstract |
Title：
Applications of Photonics Sensing Abstract：
A growing concern and needed about sensing technologies to improve accuracy and quick detection. We will describe our recent works on design, testing and new applications. |
Prof. Hong Ki Tsang | Department of Electronic Engineering, The Chinese University of Hong Kong | Title and Abstract |
Title： Waveguide Grating Couplers for Silicon Photonics Abstract： We review the application of subwavelength engineering in the design of waveguide grating couplers [1-6] and describe some of our recent work on dual-band waveguide grating couplers [7] and small-footprint perfectly vertical grating couplers for waveguide to multicore fiber interfacing[8]. References 1. X. Chen and H.K. Tsang: "Nanoholes Grating Couplers for Coupling Between Silicon-on-Insulator Waveguides and Optical Fibers," IEEE Photonics Journal, 1, 184-190, 2009. 2. X. Chen, C. Li and H. K. Tsang, "Two dimensional silicon waveguide chirped grating couplers for vertical optical fibers," Optics Communications 283, 2146-2149, 2010 3. X. Chen and H.K.Tsang, "Polarization-independent grating couplers for silicon-on-insulator nanophotonic waveguides," Optics Letters, 36, 796-798, 2011 4. X. Chen, K. Xu, Z. Cheng, C. K.Y. Fung and H.K. Tsang, "Wideband subwavelength gratings for coupling between silicon-on-insulator waveguides and optical fibers," Optics Letters, 37, 3483-3485, 2012. 5. Z.Z. Cheng, Z. Li, K. Xu and H.K.Tsang, "Increase of the grating coupler bandwidth with a graphene overlay," Appl. Phys. Lett. 104 111109, 2014 6. Zhenzhou Cheng, Xia Chen, Chi Yan Wong, Ke Xu, and Hon Ki Tsang, "Broadband focusing grating couplers for suspended-membrane waveguides," Opt. Lett. 37, 5181-5183, 2012 7. Wen Zhou, Zhenzhou Cheng, Xiankai Sun, and Hon Ki Tsang, "Tailorable dual-wavelength-band coupling in a transverse-electric-mode focusing subwavelength grating coupler," Opt. Lett. 43, 2985-2988, 2018. 8. Yeyu TONG, Wen Zhou and Hon Ki Tsang, “Efficient Perfectly Vertical Grating Coupler for Multi-Core Fibers Fabricated with 193-nm DUV Lithography,” accepted for Optics Letters 2018. |
Prof. Milton Feng | Department of ECE, University of Illinois at Urbana-Champaign | Title and Abstract |
Title： Single Mode 850 nm Oxide-VCSELs with Mode Selective Filter for Extending 32 Gb/s Error-Free Transmission in OM4 fiber up to 500m Abstract： Short-haul optical links based on 850 nm emission wavelength optical transceivers and multimode fibers are widely deployed in large data communication applications. However, the high speed error-free transmission distance is limited to ~ 75 m for 25 Gb/s (IEEE 802.3ba) due to the chromatic and modal dispersion in MMF. For further extend distance > 75 m, the chromatic dispersion in MMF over distance can be improved by using single-mode VCSELs. By applying mode selective filter, we have developed stable 850 nm single-mode oxide-VCSELs with ITH ~ 0.7 mA, Pout > 2.6 mW, and SMSR > 32 dB at the operating current bias I = 8 mA. The VCSELs successfully deliver 32 Gb/s error-free transmission (BER<〖10〗^(-12) with at least 10 Tb data transmitted in all testing scenarios) for up to 500 m in OM4 multimode fiber without any use of pre-emphasis or error-correction techniques. |
Prof. Sien Chi | Department of Photonics/ Institute of EO Engineering, National Chiao Tung University | Title and Abstract |
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Quantum Electronics and Laser Technology |
Dr. Dimitre Dimitrov | Institute of Solid State Physics / Optical Materials and Technologies, Bulgarian Academy of Sciences | Title and Abstract |
Title： Phase change memory (PCM) technology and its application to neuromorphic computing Abstract： The realization of brain-like computer has always been an ultimate goal. Today, the possibility of having this goal achieved has been significantly boosted due to the advent of several emerging non-volatile memory technologies and devices. Within these innovative technologies, phase-change memory devices have been commonly regarded as the most promising candidate to resemble the biological brain, owing to its excellent scalability, fast switching speed, and low energy consumption. In this aspect the physical properties of phase-change materials that receive a widespread application on non-volatile memory field will be discussed. We then survey the recent research on different types of neuromorphic circuits using phase-change materials in terms of their respective geometrical architecture and physical schemes to reproduce the biological events of human brain. Finally, the current status of the neuromorphic computing application of phase change memories and future prospects are envisioned. |
Prof. Jean-Claude Diels | Physics and Electrical Engineering, University of New Mexico | Title and Abstract |
Title： Reaching the ultimate detection sensitivity by beating two correlated frequency combs issued from the same laser Abstract： Most sensors are based on an interferometer or resonator, of which a narrow resonance is modi ed by the parameter to be measured. The measurement is that of the amplitude of the signal transmitted by the resonator. The lower the losses, the highest the sensitivity, hence it is not surprising to expect the highest sensitivity in a laser where the gain compensates the losses. A small perturbation introduced inside the laser can affect its frequency, which in turns becomes a metric of that perturbation (caused by an electric or magnetic eld, rotation, acceleration, nonlinear index of refraction etc). The measurement is performed by interfering two frequency combs | a reference and a signal comb | on a detector. The signal to noise is exceptionally high (and optical path difference of less than 1 femtometer has been demonstrated) because the two combs are correlated, being created in a single (unstabilized) laser. It will be shown that this exquisite sensitivity can be enhanced by orders of magnitude inserting resonant elements inside the laser cavity. Prospects for the development of compact ber and integrated optics devices will be discussed. |
Prof. Marion Joseph Soileau, Jr. | Optics, ECE, and Physics, CREOL, The College of Optics and Photonics, University of Central Florida | Title and Abstract |
Title： Surface interactions of few-cycle infrared laser pulses with optical materials Abstract： Within one year of the demonstration of the first laser, Q-switching was demonstrated, and resulted in high-peak power, short-pulse laser systems. Limitations of laser systems due to laser-induced damage on optical components followed. Short pulsed lasers have progressed as better optical materials with higher laser-resistance were developed, the nonlinear optical effects have been better understood and managed, and chirped pulse amplification technique was developed (the subject of the 2018 Nobel Prize in physics awarded to Gerard Mourou and Donna Strickland). In turn, high power, ultra-short pulse lasers have become an important tool in studying optical materials. In this work, we report studies of surface modifications in ZnSe with 11.5 fs, mid-infrared few-cycle pulses. Single shot and multi-shot laser irradiations were studied with terawatt power. Periodic surface structures were generated and growth defects were revealed as pulse number increased. |
Dr. Hung-Pin Chung | Department of Optics and Photonics, National Central University · | Title and Abstract |
Title： Quantum polarization states measurement via metasurface reconstruction Abstract： We demonstrated the generation of polarization-entangled photon-pairs via the type-II spontaneous parametric down conversion (SPDC) process in domain-engineered titanium-diffused periodically poled lithium niobate waveguides (Ti: PPLN/W). The performance of the SPDC source has been tested using the classical sum-frequency generation (SFG) technique based on the SFG-SPDC analogy. The classical measurement results showed that the SFG conversion efficiency under a pump power of 0.319 mW and a conversion bandwidth (FWHM) of 0.43 nm is about 4.33 x 10-5, from which we estimated a SPDC photon-pair generation rate to be 2.69 x 107 Hz when a 20-mm long PPLN waveguide pumped by a 1-mW 785-nm laser was used. The quantum features of the generated cross-polarization photon source have been verified not only by the traditional quantum tomography and Hong-Ou-Mandel (HOM) interferometry, but also by a novel metasurface reconstruction methodology in both heralded single-photon and two-photon states. According to the HOM measurement results, we estimated this photon-pair source provides a 66.82 % purity in partially coherent state or an intermediate degree of entanglement. The reconstruction results illustrate the manifestation of multiphoton quantum interference on metasurfaces with the fidelity of 95.24 % and 98.54 % in the case of cross-polarized and twofold correlation photon-pairs. |
Holography and Information Processing |
Prof. Tsutomu Shimura | Institute of Industrial Science, the University of Tokyo | Title and Abstract |
Title： Time series signal holographic memories Abstract： I will introduce holographic data storage systems that write and read multi-channel time series signals. Physically, the system is the same as normal page data based holographic memory system, but each pixel of the page based system acts as a channel that carries a time series signal. The time series signal system can be realized in both angle multiplexed and collinear systems, and amplitude, phase, polarization modulated signals can be used. Because Run Length Limited coding can be applied to these systems, the unit angle or shift length for the time series signal can be smaller than the page separation in the page data based systems. Thus, the data storage density can be much larger than that of the conventional systems. Also, it is a great advantage that matured signal processing technique for the time series signal be applied to these systems. I will show some numerical and experimental results in these systems, and discuss the signal quality and write-read properties. |
Prof. Vera Marinova | Bulgarian Academy of Sciences | Title and Abstract |
Title： Advances in holographic materials and devices Abstract： Recent advances in holographic materials and their combinations into hybrid structures will be discussed and their functionality demonstrated. We employed the interplay between the ability of inorganic materials to generate space charge field together with the high birefringence of organic materials into variety of electro-optically and all optically controlled devices. In addition it is found that the heterostructure consisting of graphene on the photoconductive substrates allows the space charge distributions to be written or erased in an all-optical fashion. The proposed light-assisted approaches demonstrate carrier density modulation in graphene using surface activated photorefractive phenomena. The prime significance of above hybrid structures is the ability to act as holographic gratings at Bragg matched coupling regime which opens numerous opportunities for sub-micron spatial resolution, providing super-fast response time, lower power consumption, broader viewing angles and high contrast ratio. Besides, simple fabrication procedure on large area with uniform modulation properties are critically important for rigid and flexible devices applications. |
Prof. Yoshio Hayasaki | Utsunomiya University | Title and Abstract |
Title： Single-pixel spectral camera Abstract： A single-pixel spectral camera composed of optical coding masks, a spectrometer, and a decoding computation has the important feature of no image sensor for imaging, therefore it has very simple optical and electrical architecture. A new implementation of the optical coding masks is a novelty of our research. The optical coding masks are composed of holes on a substrate, and arranged on the circumference of a disk enables us to switch with a rotation of the disk. The main feature is small wavelength dependence other than air for wideband spectral imaging. |
Prof. Ting-Chung Poon | Virginia Tech, USA | Title and Abstract |
Title：
Edge extraction in incoherent image processing using optical scanning holography Abstract：
Optical scanning holography (OSH) is a highly sophisticated technology with many facets and applications [1]. OSH is a based on a two-pupil optical heterodyning system [2]. By designing the pupils, we can obtain different computational operations achievable in the system. In this invited talk, we will concentrate on the use of OSH to achieve holographic recording of the edge information of incoherent 3D images. We will first review some of the edge extraction examples, and then we discuss the use of one of the pupils as an annular aperture with the other pupil being a delta function to extract the edge information of incoherent images holographically. We show some simulation results. |
Prof. Byoungho Lee | School of Electrical and Computer Engineering and Inter-University Semiconductor Research Center Seoul National University, Korea | Title and Abstract |
Title： Use of metasurface for 3D display applications Abstract： Metasurfaces are flat optical devices consisting of artificially fabricated photonic meta-atoms with unique optical responses, and have been extensively studied for thier extraordinary abilities to modulate electromagnetic waves. Recent advances in the metasurface have revealed that flat metasurface optics can be implemented with various functions or tremendous performance compared to conventional optics, showing great potential for future imaging applications. For example, high-quality metasurface holography with both spatial amplitude and phase information at subwavelength-scale resolution is achieved, mitigating chronic bottlenecks in traditional holograms. In addition, metasurface lenses, called metalenses, have powerful features such as a flatness, a high numerical aperture, and multi-functions that do not appear in convensional optical lenses. Based on these meta-optics, several practical studies on imaging applications have recently been reported. In this talk, we will present several optical metasurface applications for three-dimensional imaging. Physical mechanisms and concepts of various optical metasurfaces will be outlined. Then, we will discuss their recent states for optical applications such as holography, microscope, and augmented reality. Especially, our recent works will be introduced that show their feasiblity in augmented reality imaging with ultrawide field of view not shown in convensional optics. Finally, our perspectives in this area will be discussed. |
Dr. Yeh-Wei Yu | Department of Optics and Photonics, National Central University | Title and Abstract |
Title： Volume holographic optical elements: introduction and applications Abstract： We introduce the analyzation method of volume holographic optical elements. Accordingly, we build up the optical models for different volume holographic optical elements. We improve the holographic data storage system based on the proposed optical models, and further extend the application to opposite virtual objective and lens-less digital holography. |
Prof. Jung-Ping Liu | Department of Photonics, Feng Chia University | Title and Abstract |
Title： Tilt Recording of Object Light by Optical Scanning Holography Abstract： Optical scanning holography (OSH) is a scanning type, single-pixel holographic imaging technique. In OSH, a time-dependent Fresnel zone plate (TDFZP) is generated to raster scan the object. A lock-in amplifier is applied to demodulate the obtained temporal signal. As a result, a complex hologram is obtained by arranging the demodulated signal. OSH can record either a coherent hologram or an incoherent hologram. In addition, OSH has the features of pupil engineering and stereo lighting reconstruction. Because of the scanning scheme of OSH, there is no physical limitation of the sampling pitch. Although intuitively the OSH can be applied to record the off-axis hologram by using an off-axis plane wave, it is still a problem that the hologram data is redundant because of the high-spatial-frequency carrier. For this reason, we proposed a new tilt-recording scheme of OSH to record the off-axis object light without redundant data in the recorded digital hologram. The system point-spread-function and the reconstruction method are also discussed. |
Prof. Yuan Luo | Institute of Medical Device and Imaging,
National Taiwan University | Title and Abstract |
Title： Volume Holographic Fluorescence Imaging Abstract： Optical sectioning techniques offer three-dimensional information from tissues, but require individual axial planes to be imaged consecutively. We introduce active illumination, utilizing speckle or Talbot effect, and multiplexed volume holography, demonstrating three-dimensional biopsy for microscopy as well as endoscopy, without scanning. |
Prof. Ju-Yi Lee | Department of Mechanical Engineering
National Central University | Title and Abstract |
Title： Precision measurement and sensing of displacement Abstract： Displacement related measuring techniques play an important role in modem technology, being widely applied in many fields, such as in the semiconductor industry, precision manufacturing, and in metrology instruments. In current research, much attention is being paid to the development of more precise measuring devices or methods with the ability to provide exact displacement information with higher precision. Laser interferometers are very useful for displacement measurement. However, due to the fact that most interferometers are based on a non-common optical path (NCOP) design, it is difficult to avoid the problem of environmental disturbance arising from temperature fluctuations, air drift, etc. In order to improve the problems faced by the traditional interferometers, I have exerted much effort for the development of a heterodyne grating interferometer based on a quasi-common-optical-path (QCOP) configuration for displacement measurement. The QCOP configuration means that the measurement and reference beams of the interferometer have almost equivalent optical paths. Surrounding disturbances can be compensated for by this configuration, making the system less sensitive to environmental disturbances. The measurement system consists of a heterodyne light source, two-dimensional holographic grating, specially designed set of half-wave plates, and lock-in amplifiers. The QCOP design relies on the phase shift between the zeroth and first diffraction orders. The measurement system has a stability of less than 14 nm over 1 hr. Based on the QCOP design, a positioning system capable of nanometer resolution over the millimeter traveling range was developed. The device achieved a positioning resolution of 2.3 nm over a traveling range of 20 mm. |
Prof. Wei-Hung Su | Department of Materials and Optoelectronic Science,
National Sun Yat-sen University | Title and Abstract |
Title： Fringe projection techniques with volume holograms Abstract： A 3D shape measurement system using a volume hologram and an endoscope is presented. It projects a binary-encoded fringe pattern onto the inspected object, and employs an endoscope to observe the projected fringes. Fringes on the obtained image are deformed by the surface profile, and consequently are analyzable to retrieve the 3D shape. The binary-encoded pattern provides additional information to identify the fringe order. Hence surfaces with depth discontinuities can be discerned without ambiguity. The binary-encoded fringe pattern is produced by launching incoherent waves into the volume hologram. The wavelength selectivity makes the diffracted pattern not much blurred by incoherent illumination. The size of the hologram is compact and tiny. Thus, the hologram reconstructs the diffracted pattern with a large depth of focus. Only one shot measurement is needed for image processing. To inspect a dynamic object using an endoscope inside a body cavity is desirable. |
Optical Design and Testing |
Prof. Tsung-Hsun Yang | Dept. of Optics & Photonics, National Central University | Title and Abstract |
Title： Challenges and Applications of 3D Imaging Technology for Indoor Positioning and Navigation Abstract： Nowadays, 2D space mapping, positioning, and navigation has become a popular and vital function in the human daily life especially for outdoor activities. Meanwhile, positioning and navigation still needs essential progress on accuracy and precision in 3D information as marching into the indoor applications. Several promising applications are location based indoor services, private home activity, medical care, environmental monitoring, police and firefighters assistance, intelligent transportation, industrial automation, guiding of vulnerable people, surveying and geodesy, construction assistance, decoration assistance, motion capturing, AR/MR applications, etc. The practical concerns are including the accuracy, the coverage area and range, the cost, the infrastructure, the market maturity, the privacy, the update rate, the interface, the integrity, the robustness, and the availability. Instead of 3D imaging, there are several competing approaches including WLAN/WiFi, RFID, ultra-wideband, and geomagnetism system. Actually, the optical approaches are the most effective ways t to construct the 3D indoor map through triangulation, time of flight, and stereo image. In this work, we will review the existing optic technologies including stereoscopic camera, structure light projection, and LiDar technology. Then, we will introduce the image processes for the 3D positioning and navigation. Finally, we will discuss on the challenges of the 3D imaging. |
Dr. Fleming Chuang | Vice President, Coretronic Corporation | Title and Abstract |
Title： Optical design in Light Field Near-Eye-Display Abstract： Augmented reality (AR) and virtual reality (VR) are two of the ways that tech can change the way you look at the world. AR and VR are increasingly used in diversified application areas. However, the traditional stereoscopic displays in general, exists a well-known problem - VAC (Vergence-Accommodation-Conflict) in the realm of Near-Eye-Display (NED). It forces the viewer’s brain to unnaturally adapt to conflicting cues of binocular imagery for fusion from brain and fixed cue image. This contributes to visual fatigue and even cause serious side-effects in or after using the device. Light field display architectures provide a way to enable true 3D displays that provide a natural and comfortable experience. The current work is going to present the optical design techniques for time-multiplexed and space-multiplexed light field display applied in NED. This presentation will also introduce optical design techniques, key tradeoffs of LFNED for two kinds of state-of-the-art light field NED architecture. |
Prof. Cheng-Mu Tsai | Graduate Institute of Precision Engineering, National Chung Hsing University | Title and Abstract |
Title：
Beam Shaping based on Freeform Lens Abstract：
In this talk, I will present how to construct a freeform lens to make the beam with Gaussian profile into an optical distribution with rotation-symmetric user-defined profile and collimated simultaneously. In general, a beam shaping system requires two surfaces to make the output profile with uniform and collimated at the same time. One surface is responsible for the uniformity, the other one is to make the ray collimation but keep uniform. However, it is possible to convert an incoherence Gaussian beam with divergence into uniform and collimated by using only one a Fresnel surface that will be discussed in this talk. When a beam shaping profile of some applications is not uniform irradiance, it could be difficult to devise an optical system to make the beam with a desirable optical distribution and collimation simultaneously. A numerical method is a way to deduce a freeform lens for leading a collimated rotation symmetric beam profile. Two user-defined profiles (that is, triangle-like and ring distributions) are shown in this talk. The simulation results show that the triangle-like distribution has a great approximation for the ideal case. Although the original simulation of the ring distribution is different from the ideal case, the triangle-like distribution is applied to modify for the ring profile improvement. As a result, the proposed method is more flexible to devise the freeform lens of the specific distribution to conduct the desirable beam shaping profile. |
Biophotonics and Biomedical Imaging |
Prof. Paul J. Campagnola | College of Engineering University of Wisconsin-Madison | Title and Abstract |
Title： Second Harmonic Generation imaging of ovarian cancer Abstract： Remodeling of the extracellular matrix in human ovarian cancer can be reflected in increased collagen concentration, changes in alignment within fibrils and fibers and/or up-regulation of different collagen isoforms. We used pixel-based SHG polarization analyses to discriminate ex vivo human tissues (normal stroma, benign tumors, and high grade serous tumors) by: i) determination of i) helical pitch angle via the single axis molecular model, ii) dipole alignment within fibrils via anisotropy, and iii) chirality via SHG circular dichroism (SHG-CD). The largest differences were between normal stroma and benign tumors, consistent with gene expression showing Col III is up-regulated in the latter. The different tissues also displayed differing SHG anisotropies and SHG-CD responses, consistent with either Col III incorporation or randomization of Col I alignment within benign and high-grade tumors fibrils. These results collectively indicate the fibril assemblies are distinct in all tissues and likely result from synthesis of new collagen rather than remodeling of existing collagen. We also implemented a form of 3D texture analysis to delineate the fibrillar morphology observed in SHG images of normal stroma and a spectrum of ovarian benign and malignant tumors (6 classes). We developed a tailored set of 3D filters which extract textural features in the 3D image sets to build statistical models of each class. By applying k-nearest neighbor classification using these models, we achieved 83-91% accuracies for the six classes. This classification based on ECM structural changes will complement conventional classification based on genetic profiles and can serve as an additional biomarker. |
Prof. Ji-Xin Cheng | Boston University | Title and Abstract |
Title：
Eliminating Drug-Resistant Bacteria via Photobleaching of Intrinsic Chromophores Abstract：
Antibiotic resistance kills an estimated 700,000 people each year worldwide, and study predicts that this number could rise to 10 million by 2050 if efforts are not made to curtail resistance (Nature, 2017, 543:15). Yet, the pace of resistance acquisition from mutation in pathogens is faster than clinical introduction of new antibiotics. Confronted with this severe situation, health organizations are calling for alternative ways to combat the resistance. Through label-free chemical imaging of methicillin-resistant Staphylococcus aureus (MRSA), my group discovered that staphyloxanthin, an anti-oxidative carotenoid pigment residing inside the bacterium cell membrane, is prone to bleaching by blue light. We further found that photobleaching of staphyloxanthin sensitizes MRSA to low-concentration hydrogen peroxide. Using cultured S. aureus, we found this synergistic antimicrobial therapy surprisingly effective (over 2-log reduction compared to untreated). Based on this initial finding, we have maximized the efficacy of staphyloxanthin destruction through mechanistic studies and explore the potential of staphyloxanthin bleaching in eliminating MRSA in biofilms and macrophages. We elucidated changes to the bacterial membrane upon staphyloxanthin bleaching and sensitize MRSA to a broad spectrum of existing antibiotics. Notably, by exploiting the intrinsic chromophore produced by the bacteria, our method is fundamentally different from the well-developed photodynamic therapy that relies on administered agents. |
Prof. Nanguang Chen | Department of Biomedical Engineering National University of Singapore | Title and Abstract |
Title： Combining nonlinear fluorescence microscopy with focal modulation Abstract： Nonlinear fluorescence microscopy methods, including two-photon and three-photon microscopic methods, have become increasingly popular in biomedical researches. Due to highly selective excitation of fluorophores, nonlinear light microscopes enjoy a much-improved imaging depth than single photon fluorescence microscopes. With the help of low-repetition femtosecond lasers, some groups have achieved greater than 1 mm penetration depths in mouse brain. We are investigating the potential of combining nonlinear light excitation with focal modulation in attempt to further reduce the strong background and bring the penetration depth to 2 mm and above. We have been focusing on design issues of spatiotemporal phase modulator, a key component for additional background rejection. Various designs have been evaluated and optimized to achieve the best combination of modulation depth, background modulation, as well as spatial resolution. |
Prof. George Barbastathis | Massachusatts Institute of Technology | Title and Abstract |
Title： On the use of Artificial Intelligence for solving computational imaging problems Abstract： Computational Imaging systems consist of two parts: the physical part where light propagates through free space or optical elements such as lenses, prisms, etc. finally forming a raw intensity image on the digital camera; and the computational part, where algorithms try to restore the image quality or extract other type of information from the image data. A broad spectrum of computational imaging approaches exist: in one extreme, computer vision, the physical part typically comprises standard imaging optics; at the other extreme, in lens-less imaging the burden of forming images or extracting other types of information from the optical field falls entirely on the computation.
In this talk I will discuss the emerging trend in computational imaging to train deep neural networks (DNNs) to perform image extraction and restoration tasks. In several imaging experiments carried out by our group, the objects rendered “invisible” due to various adverse conditions such as extreme defocus, scatter, or very low photon counts were “revealed” after processing of the raw images by DNNs. The DNNs were trained from examples consisting of pairs of known objects and their corresponding raw images. The objects were drawn from databases of faces and natural images, with the brightness converted to phase through a liquidcrystal spatial phase modulator. After training, the DNNs were capable of recovering unknown, i.e. hitherto not presented during training, objects from the raw images and recovery was robust to disturbances in the optical system, such as additional defocus or various misalignments. This suggests that DNNs may form robust internal models of the physics of light propagation and detection and generalize priors from the training set. |
Prof. Eiji Okada | Keio University | Title and Abstract |
Title： Optical and numerical phantoms for near-infrared imaging of brain function Abstract： Functional near-infrared imaging has been widely applied to a variety of brain function studies and clinical measurements. Imaging phantoms are used to evaluate and calibrate the performance of medical imaging equipment. The phantoms are quite important for near-infrared imaging of brain function because the brain function images measured by the near-infrared imaging instruments are affected by the scattering of the tissue and depend on the probe arrangement on the head. In this talk, I will present two types of the phantoms for functional near-infrared imaging of brain function. The optical phantoms are composed of solid and liquid materials. The image is obtained from the intensity change caused by the absorber mimicking the brain activation detected by the probe pairs attached to the phantom surface. Numerical phantoms are more flexible than the optical phantom and can realize the complex anatomical structure of the head. Light propagation in the phantom is numerically calculated to obtain the functional image. The numerical phantom is effective to evaluate the influence of the extracerebral tissue structure and probe arrangement of the near-infrared imaging instruments on the brain function image. |
Prof. Chen-Yuan Dong | Department of Physics, National Taiwan University | Title and Abstract |
Title： High Content Multiphoton Tissue Cytometry for Connectome and Cancer Biology Abstract： In the decades since the invention of multiphoton microscopy, this imaging modality continues to make significant impact in diverse fields of biology and medicine. In my lab, we have been developing nonlinear optical imaging to address basic physiological questions and seeking medical applications. The fields we have investigated include dermatology, ophthalmology, hepatology, tissue engineering, infectious diseases, and others. We have found that imaging tissue and organs at a large scale and in three dimensions can provide a wealth of structural and functional information absent in two-dimensional microscopy. Relevant to connectome and cancer biology, it has become increasing clear that developing technology that can achieve high content tissue cytometric information in three-dimensions can lead to unprecedented understanding of biology and personalized medicine. I will present results describing our efforts in these two directions. |
Display Technology |
Prof. Yasuhiro Takaki | Department of Electrical and Electronical Engineering,
Tokyo University of Agriculture and Technology | Title and Abstract |
Title： Electronic holographic displays using MEMS-SLMs Abstract： The conventional holographic displays using SLMs require approximately 1-micron pixel pitch and tremendous number of pixels to obtain practical screen size and viewing zone. The horizontal scanning holography employing MEMS-SLMs have been developed to solve the above issue using the time-multiplexing technique. The screen scanning system, the viewing-zone scanning system, the 360-degree display system, the multi-channel system, and the color display system have been developed. |
Prof. Liang-Chy Chien | Liquid Crystal Institute, Kent State University | Title and Abstract |
Title： Cholesteric Optical Metronomes with a Flexoelectrically Programmable Amplitude Abstract： We experimentally demonstrate ultrafast flexoelectric liquid crystal displays in polymer stabilized cholesteric liquid crystals with uniform lying helix (PSULH) [1-3] and vertical standing helix (PSVSH) [4-5] modes. A method to control the flexoelectric properties of the CLC mixture by mixing nematic liquid crystal constituents is achieved by addition of a giant flexoelastic coefficient bimesogenic LC dimer into a low dielectric anisotropy commercial NLC mixture. High optical contrast is achieved with flexoelectrically driven in-plane or out-of-plane rotation of the cholesteric helical axis in a well-aligned PSULH or PSVSH texture [6-7]. The PSULH prototype sample reveals a sub-millisecond response time for switching between electric field on and off states, the change of polarity of applied electric field, and with high contrast ratio. A PSVSH device exhibits a response time of less than 0.7 ms, low hysteresis and color dispersion and 500:1 contrast ratio [8-9]. Detailed optical and electro-optical properties as well as computer simulations of flexoelectric-switching for flexoelectric mixtures with different flexoelectric coefficients will be presented. Our findings identified quality of ULH alignment and dark state of VSH, and material miscibility challenges, and will be useful for material design of future CLC mixtures for applications in field-sequential color displays and flexoelectro-optic elements. |
Prof. Jongwook Park | Department of Chemical Engineering, Kyung Hee University | Title and Abstract |
Title： Highly Efficient Fluorescent Blue-light Emitter with More Than 30,000 Hour-Long Lifetime Abstract： In this study four emitters of blue light are synthesized by selecting pyrene, with its high photoluminescence quantum yield (PLQY), as the core group and variants of the electron-donating diphenylamine (DPA) as side groups. The four compounds have different numbers, sizes, and substitution positions of alkyl groups on the DPA. Each of the four compounds when doped in OLED devices shows a high current efficiency (CE) of over 7 cd A-1 and a high external quantum efficiency (EQE) of over 7.5%. In addition, the compounds yield electroluminescence (EL) spectra showing peaks with narrow full width at half maximum (FWHM) values of 37-40 nm and hence indicative of high color purity. Moreover, one compound shows a very high EQE of 9.25% and a very long lifetime, with an LT95 of 471 h. Other new blue emitters based on the core-side concept will be discussed. |
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Solid State Lighting |
Prof. Ian Ferguson | Electrical & Computer Engineering,
Missouri University of Science and Technology | Title and Abstract |
Title： ZnO: A New Substrate Technology Revisited for III-Nitride LEDs Abstract： Light emitting diodes (LEDs) are the emerging next generation lighting technology but obtaining high performance green and longer wavelength LEDs, require InGaN alloys with higher indium content has proven difficult. One major problem is that the lattice mismatch between InGaN active quantum wells and the surrounding GaN layers worsens with increasing indium content. In addition, localization mechanism associated with compositional fluctuations that allow bright LEDs in the blue is no longer valid. In this work ZnO substrates are used for GaN and InGaN growth by metalorganic chemical vapor deposition (MOCVD). ZnO offers many advantages for GaN and InGaN due to its closely matched lattice constant, similar thermal expansion coefficients, and its ability to also be easily chemically etched, which results in improved light extraction. However, H2 etching of the ZnO substrate at high temperatures, Zn diffusion out of the substrate, and the stability of an oxide substrate in a highly reducing atmosphere still cause many issues during MOCVD growth. The direct nucleation of GaInN on ZnO is considered in this work including some native and non-native III-Nitride transition layers. The transition layer was grown on the substrates before or during the MOCVD growth to prevent Zn diffusion, protect the ZnO substrate from H2 back etching, and promote high quality nitride growth on the ZnO substrates. It was found that Al2O3 grown by Atomic Layer Deposition (ALD) on ZnO was a particularly effective transition layer. High resolution x-ray diffraction (HRXRD) measurements revealed that the thin Al2O3 layers after optimal annealing showed distinct wurtzite GaN and InGaN films grown epitaxially on ZnO with a mirror-like surface, no etched pits, and no peeling off. This work was extended to LEDs grown on Si with an ALD Al2O3 transition layer and these devices had a turn on voltage of <5V. |
Dr. Pei-Ting Chou | PlayNitride Inc. | Title and Abstract |
Title： MicroLED Display Applications and New Opportunities Abstract： MicroLED display is believed to be the next generation of flat panel display. The concept of MicroLED display is simple. It can be considered as an LED video wall but shrunk into consumer product sizes with micro-meter scale LED chips as sub-pixel emitting elements. The reasons to develop MicroLED display are lower energy consumption and better environmental reliability. Current LCD is a light absorbing device, which means most of light from backlight unit is wasted and transformed to heat. This will be a big energy crisis while we use more and more displays. OLED seems can reduce some energy consumption as an emissive display, but it is limited by material lifetime and weak environmental reliability. MicroLED could be a good solution by highly efficient inorganic LED chips. MicroLED display can meet all requirements for high performance display. It can achieve ultra-high resolution, ultra-low power consumption, high brightness, flexible display with any shape, fast response time, and good environmental reliability. MicroLED is the only display technology can fulfill high display quality standard, and we believed MicroLED will be the ultimate display technology. By using PlayNitride proprietary PixeLED® display technology, we have built 3.12” 256x256 pixels and 5” 320x160 pixels full color MicroLED sample. This sample was built by passive matrix backplane, red, green, and blue MicroLED chips, and a passive matrix OLED driver IC. Both displays are transparent with more than 50% transmittance, and high brightness more than 800 nits. MicroLED display is an emerging technology with high brightness, wide color gamut, and high aperture ratio. In additional to traditional display applications, MicroLED display can be used for innovative display technology. Based on our proprietary PixeLEDTM Display technology, we demonstrated two MicroLED displays which can show the ultimate display performance. |
Prof. Tien-Chang Lu | Department of Photonics/ Institute of EO Engineering, National Chiao Tung University | Title and Abstract |
Title： Study of Solution-Processed Perovskite Random Lasers Abstract： Solution-processed organic-inorganic metal-halide perovskites have been considered as an alternative material for the cost-effective and large-scale manufacturing in variety of optoelectronic devices [1]. Moreover, several advanced researches recently indicate that the perovskites show excellent material properties such as the promising photoluminescence (PL) quantum efficiencies exceeding 70 % and broad emission spectra covering most of the visible range with compositional adjustment, making them feasible for efficient on-chip coherent light-emitting devices [2]. Despite many laser cavities have been proposed to support the lasing action of perovskites from different fabrication processes, for example, crystalline microcavity, nanowire cavity, vertical cavity with both dielectric coated DBRs, and thin film cavity with surface grating, perovskite thin film itself exhibits the random lasing performance even without any resonant cavity. We are the first few groups that demonstrated random lasing behaviors from the solution processed CH3NH3PbI3 thin film at low temperature and reported the phase transition behavior [3]. We also observed the effect of nano-crystalline structures existed in the perovskite thin films on the performance of lasing process [4]. In order to further increase the operation temperature, we applied plasmonic structures on the perovskite thin film to further improve the laser performance by employing the stronger interaction between light and perovskite gain medium [5]. Recently, we exploited the novel solvent-engineered method to make solution-processed methylammonium lead bromide perovskite thin films with excellent optical properties. The random operation can be easily observed at above room temperature condition. Furthermore, with the perovskite synthesized on flexible polyimide (PI) substrates, the lasing performance can be actively controlled via the bending modulation of the supporting substrates, offering a new route to develop the wearable optoelectronic devices. Finally, we applied this random laser light source for the imaging of a simple double-slits system and AF resolution test chart. The acquired low spatial coherence and high contrast-to-noise ratio indicate that such a perovskite thin film random laser can be applied for the advanced speckle-free imaging [6]. |
Photovoltaic Technology |
Prof. Wolfgang Diehl | Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig | Title and Abstract |
Title： Plasma Meets Photonics – Thin Film Coatings for Display Applications Abstract： Thin functional coatings are the key to new and superior products in nearly all industrial branches. The most flexible and widely used technology for the deposition of thin films are plasma processes. These technologies are the first choice for an enormous bandwidth of materials and functions to be realized. The talk will give an overview of functional coatings with recent applications and will focus on the available process technologies for thin film deposition ranging from well established PVD processes like DC magnetron sputtering and PACVD to new and specialized technologies like atmospheric pressure plasma processes or gas flow sputtering and hot topic technologies of highly ionised pulse plasma processes (HIPIMS). -Transparent conductive oxides TCOs are of major importance in photovoltaics or displays and can be deposited by reactive magnetron sputtering. Photo induced Hydrophilicity and photocatalytic decomposition of organic material can be achieved by coatings with crystalline TiO2. Design and manufacturing of complex optical filters will be demonstrated using a new Optics Coating Plant technology as well as investigating antireflective coatings and materials. Targeted surface functionalization or coating can be achieved by means of atmospheric pressure plasma processes. |
Prof. Tae-Woo Lee | Department of Materials Science and Engineering, Seoul National University | Title and Abstract |
Title： Interfacial modification in metal halide perovskite based solar cells Abstract： Metal halide perovskites (MHPs) are promising materials for photoactive layers in solar cells (SCs) because they have outstanding advantages such as low exciton binding energy (29-50 meV for CH3NH3PbI3) and high carrier mobility (≤100 cm2/V∙s). Even though many researches on the MHP layer have been done so far, significance of interfacial layers has often been overlooked. Tailoring the interfacial energetics between an electrode and a photoactive layer in MHPs based SCs is important to maximize open circuit voltage (Voc) and thereby power conversion efficiency (PCE). Although PEDOT:PSS is the most widely used hole extraction layer (HEL), it cannot make Ohmic contact with overlying organic or perovskite photoactive layer due to its low work function (WF) of ~5.0 eV leading to decrease in Voc and thereby PCE (PCDTBT and MAPbI3 ~5.4 eV). To overcome the problem, we used a conducting polymer (CP) blend which has an increasing gradient WF from bottom to top owing to the gradient concentration of perfluorinated ionomer (PFI) in the film. Use of the CP with high WF successfully increased Voc and thereby PCE of perovskite SCs by minimizing energy offset with the photoactive layers. Also, we present MHP nanoparticles (NPs) synthesized by ligand-engineering method to make SCs with high reproducibility. MHP polycrystalline (PC) bulk film based SCs had low reproducibility due to poor surface morphology of MHP PC films. Furthermore, controlling the surface morphology of MHP PC films is very difficult because the environmental conditions such as temperature and moisture have a strong influence on the morphology. Ligand engineering methods which reduce the alkyl length of ligand improved the charge extraction/transport characteristics in MHP NP films. Our research suggests a promising way to increase the PCE in perovskite NP SCs. |
Dr. Swee Ching Tan | Department of Materials Science & Engineering, National
University of Singapore | Title and Abstract |
Title： Recent Advances in Photovoltaic Performances of Purple-Bacterial Protein Bio-hybrids Abstract： Photosynthesis, a process by which plants convert sunlight, water, and carbon dioxide into biomass, is key to the sustenance of nearly every form of life on earth. At the heart of this process are the photosynthetic pigment-protein complexes that transduce solar energy into biologically useful forms of energy through a photochemical charge separation that has a quantum efficiency close to 100%. Although the protein complexes exhibit a near-unity quantum efficiency in their native environments, achieving a similar photoelectric performance by integrating them in device environments, without losing their integrity, has been a challenge. Despite numerous efforts in the past decade on various bio-photovoltaic systems integrating purple-bacterial proteins, there has not been a satisfactory advance in the photocurrent generation in the devices. With most the reported devices being liquid electrochemical cells, challenges in getting high photocurrents in such typically stem from the limitations imposed by low light absorbance of proteins dispersed in liquid electrolytes and/or slow long-range diffusion of liquid-phase charge carriers. In this talk, I will give an overview of some of the works that enhance the photocurrent density, open-circuit voltage and stability achievable by pigment-proteins in bio-hybrid photovoltaic devices over the last few years. |
Thin-Film Technology and Optical Engineering |
Prof. Yi-Jun Jen | Department of Electro-optical Engineering, National Taipei University of Technology | Title and Abstract |
Title： Fabrication and application of stratiform metamaterial Abstract： The stratiform metamaterial composed of metal and dielectric thin films exhibits negative index or hyperbolic dispersion through a modified design method based on traditional optical coatings. The associated applications of the stratiform metamaterial including High efficient light absorption, polarization beam splitting, angular insensitive filtering, and plasmonic lithography are proposed here. |
Prof. Peter Chao-Yu Chen | Department of Photonics, National Cheng Kung University | Title and Abstract |
Title： Versatile halide perovskite thin films with unique photonic characteristics and applications Abstract： The halide perovskites materials have received tremendous attention for various photonics applications due to their unique materials properties. In this talk, we will present various halide perovskites thin film made of different compositions and structures with their characteristics in photovoltaic, light-emitting, and optical non-linear properties. For the materials composition, complex system such as multi-cation mixed halides or pseudo halides will be introduced. Their stability in photovoltaic outperform the traditional MAPbI3 in general. Furthermore, low-dimensional 2D/3D mixed perovskites will be discussed for their improved photovoltaic performances and non-linear optical properties. Such new families of organic-inorganic hybrid semiconductors has great potential for next generation photonic devices and applications. We will report the use fully inorganic materials as electrode for perovskite solar cells. One example is the ise of IZO for electron transporting layer (ETL) and NiO as hole transporting layer (HTL) to achieve the all-inorganic selective contacts perovskite solar cells. We will present the material characteristics and the photovoltaic performances using such novel configuration. The final device demonstrated a decent power conversion efficiency over 16%. More importantly, the IZO/perovskite/NiO-based solar cells showed an impressive long-term stability under air or light-soaking conditions. With encapsulation, our device remained 85% of initial power conversion efficiency after 460 hours light soaking. This significant result reveals that high device performance, low fabrication cost and impressive light-soaking stability can be realized simultaneously by employing oxide nanoparticles as selective contacts. |
Prof. Shiuh Chao | Institute of Photonics Technologies, NTHU | Title and Abstract |
Title： Low thermal noise mirror coatings for next generation laser interferometer gravitational waves detector Abstract： After the first detection of the gravitational waves on Sep. 2015, technology development of the laser interferometer gravitational waves detector is now moving toward cryogenic operation at 1550 nm or 2000nm wavelength. Brownian thermal noise of the mirror coatings is still one of the dominant factors for detector sensitivity. The technology trend and needs for the low thermal noise mirror coatings will be introduced and discussed. |