Graphene Photonic Devices Based on Long-period Grating Structures

Project: Research

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Graphene, a two-dimensional single layer of carbon atoms, has found numerousapplications in electronic devices. The unique optical properties of the material, such aselectrically tunable absorption, exceptionally strong nonlinearity, saturable absorption,efficient luminescence, etc., have also promised a wide range of applications in therealization of photonic and optoelectronic devices, such as smart displays, touch screens,ultrafast lasers, photovoltaic devices, light-emitting devices, photodetectors, sensors,polarizers, and modulators. There is a growing interest world-wide in exploring theoptical properties of graphene for various applications.Graphene photonic devices can be divided into two types: (i) waveguide devices and (ii)non-waveguide devices. Waveguide devices, where the light wave propagates along thegraphene surface, are suitable for applications that require a long light-grapheneinteraction length. Devices like polarizers and modulators, and some sensors arewaveguide devices. Non-waveguide devices, where light passes through the graphenelayer vertically, are suitable for applications like smart displays and touch screens. Theproject investigates a versatile platform for the implementation of graphene-basedwaveguide devices.The waveguide structure considered in the project consists of a long-period grating(LPG) coupled optically to a graphene layer. An LPG is a periodic structure formed in anoptical fiber or a planar waveguide to enables light coupling from the core into thecladding of the fiber/waveguide at specific wavelengths. When the light wavepropagating in the cladding is in contact with the graphene layer, any absorptionmodulation in graphene can affect the light propagation and hence the transmission ofthe LPG. This graphene-incorporated LPG structure can be explored for thedevelopment of many devices, such as optical modulators, wavelength filters,polarization-dependent loss compensators, and various kinds of sensors.The PI has more than 15 year experience in LPG research and a much longer experiencein waveguide design. CityU is equipped with the facility necessary for the fabrication ofplanar waveguides and LPGs (in fibers and waveguides). The availability of the newmaterial – graphene – offers new application possibilities for LPGs. The project willinvestigate the light-graphene interaction in LPGs and experimentally demonstrate thefeasibility of realizing graphene-incorporated LPG devices. The project will lead to anew class of graphene photonic devices based on LPG structures, which could be furtherdeveloped into practical devices for application in optical communication, optical signalprocessing, and sensing.


Project number9042029
Grant typeGRF
Effective start/end date1/01/1529/05/19

    Research areas

  • graphene,long-period fiber gratings,long-period waveguide gratings,optical waveguides,