4:00pm - 4:30pmInvited
Nanophotonics Technology and Applications
University of California San Diego, United States
Various future system applications that involve photonic technology rely on our ability to integrate it on a chip to augment and/or interact with other signals (e.g., electrical, chemical, biomedical, etc.). For example, future computing and communication systems will need integration of photonic circuits with electronics and thus require miniaturization of photonic materials, devices and subsystems. Another example, involves integration of microfluidics with nanophotonics, where former is used for particle manipulation, preparation and delivery, and the latter in a large size array form parallel detection of numerous biomedical reactions useful for healthcare applications. To advance the nanophotonics technology we established design, fabrication and testing tools. The design tools need to incorporate not only the electromagnetic equations, but also the material and quantum physics equations to include near field interactions. These designs are integrated with device fabrication and characterization to validate the device concepts and optimize their performance. Our research work emphasizes the construction of passive (e.g., engineered composite metamaterials, filters, etc.) and active (e.g., nanolasers, nonlinear wave mixers) components on-chip, with the same lithographic tools as electronics. In this talk, we discuss some of the passive metamaterials and devices that recently have been demonstrated in our lab. These include our recent results on nanoscale engineering optical nonlinearities with SOI material platform and design, fabrication and testing of nanolasers constructed using metal-dielectric-semiconductor resonators confined in all three dimensions.
4:30pm - 5:00pmInvited
Nanopillar Resonator Devices on a Silicon Substrate
University of California, Berkeley, United States
Monolithic integration of devices based upon dissimilar materials is believed to be of grave importance to achieve functionalities greater than the sum of those of the parts. In particular, it is critical to integrate active optoelectronic devices based on III-V compound, e.g. LEDs, lasers and photo transistors, with electronic circuits and silicon-photonics. Such integration can alleviate power, speed and bandwidth bottlenecks in data transport as microprocessor performance continues to scale.
I will discuss the synthesis method, material properties, device fabrication and characteristics of InP/InGaAs nanopillars directly grown on silicon at low temperatures. Optically pumped single-pillar lasers were achieved for various material compositions from 800nm-1550nm. In addition, we showed single nanopillar optically pumped laser grown on a MOSFET-silicon wafer without FET degration. I will discuss a photovoltaic device exhibiting insensitive to illumination angle and a power conversion efficiency of 19.6%. We demonstrated InP nanopillar bipolar junction phototransistors monolithically integrated on a Silicon substrate. With a responsivity of 9.5 A/W, bandwidth of 7.5 GHz and 375 GHz gain-bandwidth product. Finally, we demonstrate the first on-chip optical link constructed from InGaAs nanopillar LEDs and photodetectors directly grown on a silicon substrate, operating at multi-GHz bandwidths while consuming subpicojoule energy per bit.
Using selective area epitaxy, we also demonstrated position-controlled InP nanopillars on a Si substrates with high yield of ~97%. Nanopillars grow vertically, in single-phase, wurtzite crystalline form. Site-controlled nanopillars show excellent optical properties- narrow linewidth (~50 meV), long lifetimes ~4 ns, and high internal quantum efficiency. Core-shell p-n junction devices were grown on n-Si by introducing dopants. InGaAs/InP quantum wells were incorporated in the active region of the diode heterostructure to obtain silicon transparent electroluminescence (1500nm) from the nanopillar LED. Position controlled InP-based diodes on silicon have tremendous implications for on-chip emitters and detectors in Si photonics links.
5:00pm - 5:15pmOral
III-V Material Platforms for Active Dielectric Metasurfaces
1Data Storage Institute, Agency for Science, Technology and Research (A*STAR), Singapore; 2LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, The Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore
Dielectric metasurfaces consisting of high refractive index nanoparticles have been widely considered as an attractive alternative to plasmonic metasurfaces due to their low optical loss. Till date the research community has been mostly focused on exploring designs for improving transmission, and achieving novel polarization and phase shaping devices. Silicon, which is widely used in dielectric metasurfaces, is not an appropriate material choice for applications which require active control. In this paper, we demonstrate several dielectric metasurfaces based on GaAs and GaN material platforms which demonstrate a path towards active dielectric nanophotonics.
Patterning optically active III-V films into optical nanoantennas offers the opportunity to enhance the intrinsic luminescence and tailor the emission properties. Our experimental results show strong fluorescence enhancement from two dimensional arrays of GaAs nanoparticles at the sharp lattice resonances. This enhancement can potentially provide a path to lasing if the losses are sufficiently compensated with available gain. A major drawback of GaAs is its relatively small optical bandgap, which results in large losses at visible wavelengths. Therefore, GaAs will be a suitable material choice only for applications at near-IR wavelengths.
At visible wavelengths a wide bandgap semiconductor such as Gallium Nitride, with accompanying low loss, is an excellent material choice. GaN is commonly used in LEDs, where it is epitaxially grown on a sapphire wafer. Designing metasurfaces on top of a LED substrate can potentially improve their light extraction efficiency. However, this approach presents some unique challenges due to diffraction into the substrate. We will present our design approach and experimental verification of high efficiency beam bending (~80% efficiency into designed angle >20 deg), and polarization beam splitters on GaN platform. This platform has not yet been explored, and we believe it will open new opportunities not only for active nanophotonics but also for nonlinear and quantum nanophotonics.
5:15pm - 5:45pmInvited
Structured Light in Novel Photonic Media
1University at Buffalo, The State University of New York, United States; 2Politecnico di Milano and Istituto di Fotonica e Nanotecnologie del Consiglio Nazionale delle Ricerche, Italy
Structured light and structured matter are two fascinating branches of modern optics that recently started having a significant impact on each other. The synergy of complex beams, such as the beams carrying an orbital angular momentum (OAM), with nanostructured “engineered” media is likely to bring new dimensions to the science and applications of structured light ranging from fundamentally new regimes of spin-orbit interaction to novel ways of information encoding for the future optical communication systems. However, integrating structured light, which commonly is created using bulk optics, on miniaturized silicon chips represents a significant challenge.
We will discuss fundamental optical phenomena at the interface of singular and nonlinear optics in engineered optical media and show that the unique optical properties of optical nanostructures open unlimited prospects to “engineer” light itself. We present theoretical and experimental studies of light-matter interactions of vector and singular optical beams in optical nanostructures and microcavities. In particular, we propose several approaches to ultra-compact structured light wavefront shaping using metal-dielectric and all-dielectric resonant metasurfaces. Moreover, by exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser generating a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. We show that the polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes.
5:45pm - 6:15pmInvited
Dynamic Plasmonic Colour Display
Max Planck Institute for Intelligent Systems, Germany
Plasmonic colour printing based on engineered metasurfaces has revolutionized colour display science due to its unprecedented subwavelength resolution and high-density optical data storage.However, advanced plasmonic displays with novel functionalities including dynamic multicolour printing, animations, and highly secure encryptionhave remained in their infancy. We demonstrate dynamic plasmonic colour displays which possess all the aforementioned functionalities based on catalytic magnesium (Mg) metasurfaces. Controlled hydrogenation and dehydrogenation of the constituent Mg nanoparticles, which serve as dynamic pixels, allow for plasmonic colour printing, tuning, erasing, and restoring. Different dynamic pixels feature distinct colour transformation kinetics, enabling the first plasmonic animations. Through smart material processing, information encoded on selected pixels, which are indiscernible to both optical and scanning electron microscopies, can only be read out using hydrogen as decoding key, suggesting a new generation of information encryption and anti-counterfeiting applications.