60 research outputs found
Tunable Silicon integrated photonics based on functional materials
This thesis is concerned with the design, fabrication, testing and development of tunable silicon photonic integrated circuits based on functional materials. This tunability is achieved by integrating liquid crystals, 2D materials and chalcogenide phase-change materials with silicon and silicon nitride integrated circuits. Switching the functional materials between their various states results in dramatic changes in the optical properties, with consequent changes in the optical response of the individual devices. Furthermore, such changes are volatile or non-volatile depending on the materials.Engineering and Physical Sciences Research Council (EPSRC
Novel fluid materials for CMOS photonic WDM systems
We propose a simple and low-cost WDM (Wavelength division multiplexing) system
(Fig 1a) based on novel fluid materials using micro-ring multichannel filter design with
in-situ, electrically and magnetically tunable, integrated 2D liquid crystal
nanocomposite materials. We achieved a quality factor on the order of 10# − 10% and
fine tuning within the entire C-band range.Engineering and Physical Sciences Research Council (EPSRC
Liquid Crystal WDM filter in Si photonic crystal technology with individual channel fine-tuning capability
We demonstrate a simple, low-cost solution for a single multi-channel WDM (Wavelength Division Multiplexing) filter with fine–tuning capability of individual channels. The filter is based on Si photonic crystal technology and can be integrated with CMOS processes. Although, fabrication technologies of Si integrated WDM systems have significantly advanced over the last decade, the most difficult challenges are posed by wavelength accuracy control as well as wavelength drifts and optical switching time. The proposed novel design of a multichannel integrated filter is based on the 1D silicon photonic crystal (PhC) model. By infiltration of the certain grooves of 1D PhC with matching filler, an efficient coupled Fabry-Pérot microresonator can be realized in which the wide-band stop band (SB) is used for frequency channel separation. By using the commercial nematic liquid crystal 5CB [1], we demonstrated electro-optical switching in the range of 30-50 nanoseconds and the continuous tuning of the individual channels up to 30 % of the channel-spacing. The fabricated multichannel filters have bandwidth of 0.1-0.9 nm with high extinction ration of 20dB at high modulation of reflection/ transmission coefficient. Using the gap map approach as a core engineering tool allows to predict formation and separation of transmission channels within the SBs and, thus, effectively determine the exact design parameters of the optical device. The obtained experimental spectral characteristics in the NIR range around 1.31 and 1.55 μm validated the proposed method and its applicability for the wavelength selective switching (WSS) as well as for the WDM in Si chip optical interconnects. [1] M. W. Geis, T. M. Lyszczarz, R. M. Osgood, and B. R. Kimball, " 30 to 50 ns liquid-crystal optical switches", Opt. Express 18, 18886-18893 (2010)The authors acknowledge the EPSRC Centre for Doctoral Training in
Metamaterials, Exeter, Devon for the continue support in this project
Tuning silicon-rich nitride microring resonances with graphene capacitors for high-performance computing applications
This is the final version. Available from the Optical Society of America via the DOI in this record.We demonstrate the potential of a graphene capacitor structure on silicon-richnitride micro-ring resonators for multitasking operations within high performance computing.Capacitor structures formed by two graphene sheets separated by a 10 nm insulating siliconnitride layer are considered. Hybrid integrated photonic structures are then designed to exploitthe electro-absorptive operation of the graphene capacitor to tuneably control the transmissionand attenuation of different wavelengths of light. By tuning the capacitor length, a shift in theresonant wavelength is produced giving rise to a broadband multilevel photonic volatile memory.The advantages of using silicon-rich nitride as the waveguiding material in place of the moreconventional silicon nitride (Si3N4) are shown, with a doubling of the device’s operationalbandwidth from 31.2 to 62.41 GHz achieved while also allowing a smaller device footprint.A systematic evaluation of the device’s performance and energy consumption is presented.A difference in the extinction ratio between the ON and OFF states of 16.5 dB and energyconsumptions of<0.3 pJ/bit are obtained. Finally, it has been demonstrated that increasing thepermittivity of the insulator layer in the capacitor structure, the energy consumption per bit canbe reduced even further. Overall, the resonance tuning enabled by the novel graphene capacitormakes it a key component for future multilevel photonic memories and optical routing in highperformance computing.Engineering and Physical Sciences Research Council (EPSRC
Multichannel Si Photonic Crystal filters with Fine-Tuning Capability of Individual Channels for WDM optical interconnects
This is the author accepted manuscriptWe demonstrate a simple, low-cost solution for a single multi-channel WDM (Wavelength Division Multiplexing) filter with fine-tuning capability at the level of the individual channels. The filter is based on silicon photonic crystal and microfluidic technologies and can be integrated with CMOS processes.Engineering and Physical Sciences Research Council (EPSRC
Hormigón conductor con fibras de carbono recicladas para aplicaciones calefactables en mobiliario urbano
This paper presents a broad experimental study performed at laboratory and industrial facilities to develop conductive concrete for self-heating and de-icing applications in urban furniture. Self-heating capacity is achieved by the application of electric current through a highly dense matrix containing recycled carbon fibers and graphite flakes. Prisms and slabs were fabricated with two different conductive concretes and electrode conÂfigurations to characterize the electrical properties and heating performance. Finally, 3 benches with different electrode disposals were fabricated to assess the heating capacity in real-scale applications. The results presented indicate promising results about the use of recycled carbon fibers for electrothermal concrete applications and identify the electrode configuration that allows the most efficient heat transfer and reduction of temperature gradients within the heated element. Real-scale tests show that the current technology developed is potentially applicable at de-icing applications in climates where temperatures remain within the range of -3 or -5 ºC.Este artÃculo presenta un extenso trabajo experimental a escala laboratorio e industrial para desarrollar mobiliario urbano con hormigones conductores calefactables. La capacidad calefactable se alcanza mediante la aplicación de corriente eléctrica por una matriz de hormigón con fibras de carbono recicladas y escamas de grafito. Se fabricaron prismas y losas con dos hormigones conductores y distintas configuraciones de electrodos para caracterizar sus propiedades eléctricas y capacidad calefactora. Finalmente, se fabricaron 3 bancos para evaluar la capacidad de calentamiento en aplicaciones a escala real. Los resultados muestran el potencial de las fibras de carbono recicladas para su uso en aplicaciones electrotérmicas e identifican las configuraciones de elecÂtrodos más adecuadas para reducir los gradientes de temperatura dentro del elemento calefactado. Por último, los ensayos a escala real muestran que la tecnologÃa desarrollada es potencialmente válida para aplicaciones de des-hielo en climas donde la temperatura varÃa entorno los -3 y -5 ºC
O-band N-rich silicon nitride MZI based on GST
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordWe have experimentally demonstrated an O-band Mach-Zehnder interferometer (MZI) based on a N-rich silicon nitride
platform combined with Ge2Sb2Te5 for future optical communication applications. The device operation relies on
controlling the waveguide’s losses using a phase change material cell which can be changed from amorphous (lowloss) to crystalline (high-loss). An extinction ratio (ER) as high as 11 dB was obtained between the amorphous (ON)
and the crystalline (OFF) states of the MZI optical building block. The insertion loss of the MZI structure per cell
unit length was measured to be as high as 0.87 dB/µm in OFF state and as low as 0.064 dB/µm in ON state for TM
polarisation.Engineering and Physical Sciences Research Council (EPSRC
A plasmonic route towards the energy scaling of on-chip integrated all-photonic phase-change memories
This is the author accepted manuscript.Phase-change photonic memory devices, conventionally implemented as a thin layer of phase-change material deposited on the top of an integrated Si or SiN waveguide, have the flexibility to be applied in a widely diverse context, as a pure memory device, a logic gate, an arithmetic processing unit and for biologically inspired computing. In all such applications increasing the speed, and reducing the power consumption, of the phase-switching process is most desirable. In this work, therefore, we investigate, via simulation, a novel integrated photonic device architecture that exploits plasmonic effects to enhance the light-matter interaction. Our device comprises a dimer nanoantenna fabricated on top of a SiN waveguide and with a phase-change material deposited into the gap between the two nanoantenna halves. We observed very considerably increased device speeds and reduced energy requirements, of up to two orders of magnitude, when compared to the conventional structure.Engineering and Physical Sciences Research Council (EPSRC
Reconfigurable photonic integrated circuits (RPICs) based on functional materials for integrated optical communication applications
This is the final version. Available from the publisher via the DOI in this record.In this work we combine the already mature silicon and silicon nitride platforms with novel reconfigurable
materials such as 2D materials, liquid crystals and phase change materials. An actively reconfigurable 1D
photonic crystal multi-channel filter based on Si-on-insulator and liquid crystal platforms is demonstrated with
extraordinary large quality factor, Q ∼ 104
. A complete study and design of an optical routing and multilevel
volatile photonic memory based on graphene capacitor concept for future high performance computing using
Silicon rich nitride is shown with a bandwidth of 64 GHz and energy power consumption per bit as low as
0.22 pJ. Finally, an optical switch based on germanium-antimony-tellurium phase change material (GST) is
experimentally demonstrated for O-band operation with the extinction ratio as high as 10 dB between the
amorphous and the crystalline statesEngineering and Physical Sciences Research Council (EPSRC
Spatial tracking of individual fluid dispersed particles via Raman spectroscopy
This is the final version. Available on open access from Nature Research via the DOI in this recordWe demonstrate a method for the spatial tracking of individual particles, dispersed in a fluid host, via Raman spectroscopy. The effect of moving a particle upon the intensity of different bands within its Raman spectrum is first established computationally through a scattering matrix method. By comparing an experimental spectrum to the computational analysis, we show that the position of the particle can be obtained. We apply this method to the specific cases of molybdenum disulfide and graphene oxide particles, dispersed in a nematic liquid crystal, and contained within a microfluidic channel. By considering the ratio and difference between the intensities of the two Raman bands of molybdenum disulfide and graphene oxide, we demonstrate that an accurate position can be obtained in two dimensions.Engineering and Physical Sciences Research Council (EPSRC)Federal Target Program of the Ministry of Science and Higher Education of the Russian Federatio
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