Photonics & Plasmonics (PnP Group)

Research Areas

By leveraging on advanced computational platforms and software, both in collaboration with academia and industry, we have been involved in a number of exciting projects with industry and academia in topics such as development of complex and high-speed photonic modelling and simulation, optimization of optical tapers for light insertion into an integrated circuit, active light-sources and high power lasers, and optical gratings. On the other hand, our group also strengthened our capability in photonic crystals and quasi-crystals for applications requiring high catchment & localization of light. In combination with the existing know-how and innovations for conventional photonics developed over the year, photonic crystals is expected to achieve substantial performance gains and/or power savings to support the photonics and Infocomm (data centres in particular) industry in Singapore. Moreover, we also aim to invest in new research initiative by means of quantum photonics by addressing: (1)-development of efficient interfaces between solid-state single photon sources and photonic circuits, and (2)-design of scalable and fabrication-friendly room temperature devices to generate, transfer, manipulate and detect quantum information encoded in single photons for the quantum data ecosystem, sensing and metrology. 

The optical engineering capability was centered on the applications of optics in the design of micro- and nanostructures to obtain multi-functional coatings and devices with specific characteristics, such as micro-cavities for lasing applications, anti-reflection & anti-bacterial coating, privacy thin film, and micro lens. Moreover, in view of the rapid proliferation of nanoimprinting technologies worldwide, PnP leverages on this global trend and initiated the capability development in optical engineering to explore the design of nano-imprinted nanostructures for optical & photovoltaic applications. One of recent involvement for the urban living application is to work on the development of microstructured multi-layered optical devices for the natural sunlight illumination of high-rise or underground buildings.

PnP group devoted substantial efforts in the Metamaterial & plasmonics capability to identify ways to significantly improve the performance of existing electrical systems by taking the advantages of the ultra-compactness of electronics and the super-wide bandwidth of photonics. The capability building for this area was accelerated through the funding of the SERC Thematic Strategic Research Programme (TSRP): Metamaterials programme in 2010. There were two projects (1) Super-resolution imaging and (2) Plasmonics based nanophotonics. Through this programme PnP successfully developed the following capabilities: metamaterial structures based antenna design, system level modelling of subwavelength imaging, a hybrid plasmonic waveguide platform, plasmonic modulators and detectors, and active plasmonic device design using high performance computing for the calculations of unconventional optical material’s properties (in collaboration with the Material Science & Engineering Department within IHPC). Subsequently, the capability building has been extended to achieve “Electrical generation and control plasmons, within small structures on single chips and to implement this technology to bypass inherent limitations in current optics and micro-electronics” with the award together with other collaborators from National University of Singapore and Institute of Materials Research and Engineering under the National Research Foundation Competitive Research Programme. The capability building is currently on-going to bring the application of plasmonic technology to bridge the gap between the photonic and CMOS devices for industrial translation in the semiconductor electronics industry. 

Biomedical technology is an important emerging industry sector. One of the most promising applications of plasmonics identified by the community then is sensing. Plasmonic sensing is expected to make an immediate impact to the biomedical industry sector by increasing the sensitivity over existing techniques by at least an order of magnitude. Thus, the decision to develop the capability in biomedical plasmonics is straight forward as there is a potential quantum leap in performance of current biosensing techniques with the incorporation of plasmonic structures. PnP group has participated in the SERC TSRP: Integrated Nano-Photo-Bio-Interface Programme, which focuses on the Development of Highly Sensitive Localized Surface Plasmon Resonance Technology Platform for Point-Of-Care Clinical Screening and Medical Diagnostics. We also led a Joint Council Office (JCO) funded project on Chiral Nanostructure based Biosensor. We has built a unique set of capabilities in plasmonic sensing structure design and modelling, chiral nanostructure design and modelling, to detect a wide range of molecules from nanometres to micrometres, such as Prostate-specific antigen, MicroRNA, E-coli, proteins and chiral molecules. Moreover, PnP group is also engaging with the industrial company to work with us on plasmon-enhanced fluorescence to improve the polymerase chain reaction detection efficiency. Recently, the research in plasmonic sensing also extended to Consumer Care application under Plasmonics-shine research direction. In particular, we have developed novel cosmetic microparticles which are able to function as both pigment and sunscreen at the same time, based on the surface plasmon resonance phenomenon. 

Disruptive technologies in nanophotonics research are promising as good innovative platforms that could help to create new capabilities and new value R&D for optics and photonics. These technologies can range from investigations to building, manipulating, and characterizing optically active nanostructures with a view to creating new capabilities in instrumentation for the nanoscale, chemical and biomedical sensing, information and communications technologies, enhanced solar cells and lighting, disease treatment, environmental remediation, and many other applications. Moving forward for the future need, we are also interesting to put effort to develop new capabilities to advance science and engineering of light-matter interactions that take place at wavelength and subwavelength scales where the physical, chemical, or structural nature of natural or artificial nanostructure matter controls the interactions. In particular, some capabilities have been built to work on these areas including quantum Plasmonics and plasmon-enhanced photocatalysis:

  1. Quantum Plasmonics
    We have successfully developed the quantum corrected optical modeling theory to understand quantum properties of surface plasmons (e.g. quantum size effect and quantum tunnelling effect). We are able to design, model and simulate the efficiency of single emitters coupled to nanoplasmonic structure cavity.

  2. Hybrid metal-semiconductor structures for photocatalysis
    The capability we have built up here is to design and optimize the plasmon-enhanced photocatalyst, including the structure and the material. Taking plasmonic-metal@semiconductor-microsphere (i.e. plasmonic metal nanoparticles encapsulated by a large semiconductor microsphere) as an example, the semiconductor microsphere’s diameter and refractive index, the plasmonic metal nanoparticle’s diameter and material of choice, how to distribute the  metal nanoparticles within a semiconductor microsphere etc. are the typical parameters to design and optimize.

  3. Dielectric nanoantenna
    Conventional research in plasmonics is based on metal, but as early as in 2010, EP already showed that dielectric structures can scatter light more efficiently than metal nanostructures during the solar cell research. This motivated us to extend the work to other materials. The dielectric nanoantenna is a new research field which appeared a few years ago and now gaining increasingly number of scientific publications. The unique advantages of this new approach is the high-index dielectric and semiconductor nanostructures possess similar (or sometimes better) resonant optical properties as plasmonic nanostructures but can be fully free of energy losses. They can be realized with standard technological materials such as silicon or other group IV and III-V semiconductors. Also, high-index semiconductors may combine their advanced electronic properties with highly resonant optical behaviour to achieve new and unique functionalities.