1,720,968 research outputs found
Ductile dicing of LiNbO<sub>3</sub> ridge waveguide facets to achieve 0.29 nm surface roughness in single process step
No full textA single-step ductile dicing process capable of manufacturing optical quality facets in lithium niobate (LiNbO3) ridge waveguides with an average surface roughness of 0.29 nm is reported. This result is comparable with surface roughnesses achieved by lapping and polishing and represents an order of magnitude improvement over the prior state of the art in LiNbO3 waveguide facet dicing
Optomechanical cantilever device for displacement sensing and variable attenuator
No full textAn optomechanical double cantilever device has been fabricated with applications as a displacement sensor and variable attenuator. The device is based on a silica glass on silicon substrate. A novel fabrication approach using a precision dicing saw is used, which has benefits in terms of cost, fabrication time and energy consumption compared to cleanroom based lithography techniques. The silica cantilevers contain integrated optical waveguides and Bragg gratings fabricated using a Direct UV Writing process. The cantilevers are deflected out of plane by thin film stress effects, providing a suitable geometry for use in sensing. Displacement causes both cantilevers to move simultaneously resulting in variable coupling due to the angular alignment of the waveguide modes. Using a developed ratiometric approach based on fitting to Gaussian apodized Bragg gratings, the measured displacement is completely independent of fluctuations in light source power as well as insensitive to detector noise. The device is optically interrogated at a wavelength band around 1550nm. As a sensor the device has a sensitivity of 0.8 dB/micron and can be accurately modelled using fiber optic coupling misalignment theory. When operating as an attenuator, a suppression ratio of over 20dB can be obtained. If combined with integrated optical components such as X-couplers, multiple double cantilever arrays can be placed on the same chip for distributed sensing. We will report detailed fabrication procedures as well as optical characterization of the device including the performance metrics of the force sensor
Tilted Bragg grating based optical components within an integrated planar platform
No full textTilted Bragg gratings (TBGs) have been shown to have a number of practical uses in planar geometries, demonstrating polarization capabilities and allowing excitation of surface plasmons. Fabrication and characterization of TBGs has been carried out in silica-on-silicon waveguides to highlight potential planar applications. An initial investigation into the coupling behaviour of TBGs has been undertaken, with greater than -20 dB coupling achieved for even small angle gratings (5°). Experimental analysis of these TBG systems provides insight into future applications of the planarized devices
Micromilling with nanoscale roughness for silica photonics
No full textWe present Flame Hydrolysis Deposition (FHD) silica micromilled with nanoscale surface roughness, sub-micron form control and micron scale depths of cut for photonic applications. Using our in-house developed high-precision micromill and industrially standard micromill tools, we have machined slots 1.5 mm long and 17 µm deep, enabling access and interaction with the evanescent field of nearby UV-written waveguides. Potential applications vary from: biological sensing, plasmonic devices, refractometers and chemical sensing. The micromilling approach offers advantages over conventional cleanroom and laser-based machining of optical materials in both form control and achievable surface roughness. To assess optimum cutting conditions a wide parameter test was conducted, where the rotational and translational speeds were varied and feed speeds optimized to allow cutting in the high-quality low-chipping ductile regime. Whilst milling in the ductile regime our smoothest form slots had a surface roughness of 3.0 nm (Sa) at a 17.0µm depth of cut. This represents a forty times increase in cut depth and an eight times improvement in surface roughness over previously reported silica slot micromilling. We will present our latest machining results with studies into sequential slot milling and report on the subsequent slot form, surface roughness, and mill wear from prolonged sequential machining. We will also show results of integrating milled slots with optical waveguides and Bragg gratings to create refractometer devices
Integrated optical circuits for quantum information processing
No full textIntegrated optical waveguide circuits are becoming increasingly important in quantum information processing. They provide a platform that is scaleable to multiple qubits, offers stability over the timescales required for multiple photon coincidence based measurements, and by utilizing telecommunications sources and hardware, allows low-loss and efficient operation. This work will present recent results and indicate research directions that are leading towards the demonstration of the required range of functions on chip, particularly on chip, sources, system tomography, phase control operations and detection
At the cross-roads of effective quantum information processing with integrated optical gates
No full textThe use of a silica integrated optical platform developed for the telecoms industry is allowing demonstrations of quantum operations with single photons and Bragg gratings that are challenging notions of classical computing. Operations such as Boson Sampling, number resolving photon detection at 1550nm, quantum teleportation and non-classical interferometry will be reported
Planarized fiber-FHD optical composite
No full textTraditionally the precision placement and adhesion of optical fiber to an optical planar substrate has been made through use of solder, glass frit, glues or epoxies. These generally have disadvantages that include mechanical weakness in harsh environments (e.g. high temperature, high pressure and exposure to common solvents) and poor optical characteristics (e.g. high optical loss, high scattering and modal/refractive index mismatch with optical fiber). In this work we shall present an approach that overcomes these disadvantages, through embedding and consolidating a fiber directly upon a planar substrate layer using Flame Hydrolysis Deposition (FHD). The result is a planarized composite that is mechanically robust in harsh environments and is of planar optical quality. The deposited silica layers can be tailored in thickness, refractive index and anisotropic stress, with the ability for multiple layers to be deposited sequentially to achieve planar guiding. The technique is compatible with a lithography toolset allowing full planar integration techniques; physical micromachining capability allowing fiber evanescent field access and Bragg grating writing. The components that can be developed using this technique include precision layer-up fiber (e.g. high density fiber packing, precision fiber lengths and delay lines), hybrid fiber-planar devices (e.g. MOEMS, evanescent field sensors and environmentally stabilised narrow line lasers) and optical pump schemes (e.g. fiber pumping, pump strippers and mode strippers). We shall report the latest developments in fabrication, capability and component
Quantifying the optical sensitivity of planar Bragg gratings in glass micro-cantilevers to physical deflection
No full textHere we introduce a novel technique for characterizing the deflection and force sensitivity of a silica micro-cantilever transducer, with inherently defined planar Bragg gratings. The technique uses a 3D scanning surface profiler to deform the micro-cantilever both vertically and horizontally whilst simultaneously monitoring a set of multiplexed Bragg gratings. By using this characterization technique a theoretical model for the cantilever's optical response is tested
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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