1,720,974 research outputs found
Optical integrated circuits for large-scale quantum networks
No full textThis thesis presents the development of a platform to fabricate photonics integrated circuits that can be used to scale networks intended for quantum information processing (QIP) experiments. The stringent technical requirements for the transport and manipulation of quantum states of light are discussed with respect to channel waveguides and integrated gratings fabricated in silica-on-silicon through direct UV writing laser processingTilted gratings are identified as a method to enable polarisation-based applications for this integrated platform. A novel implementation of in-line planar waveguide polarisers based on 45º tilted gratings is presented, demonstrating gratings with polarisation extinction ratio (PER) of 0.25 dB / mm and bandwidth impairments better than 0.3 dB in the C-band. 45º tilted gratings in UV written waveguides are used to create novel polarising coupler architectures with PER of 28.5 dB.The alteration of the material composition of germanesilicate planar core layers is investigated, producing waveguides with birefringence of 4.5 ± 0.2 × 10−4, higher than previously reported for this platform. A process for producing end facet endcaps to extend the platform’s capability for high power applications is also described. These developments offer potential for the scaling of QIP experiments with heralded spontaneous four-wave mixing single-photon sources.Finally, the thesis describes research-based education experiments conducted to inform a wide range of audiences on the importance of photonics technologies. The concept of Photonics, and the underlying science and associated research, has been introduced to 2,952 students from 81 schools in the South of England and over 6,000people in public events
Modular and extensible lesson on optical fibre communication for youths
No full textOptical fibre communication enables the global internet, but few youths ever learn about how it works, even at a basic level, until tertiary education. While some middle school curricula might include simple geometrical optics concepts like reflection and refraction, they often lack contextual linkage to worldwide telecommunications. Through our studies, we have found that students are more engaged in the learning process when the material directly relates to real life. To address this gap, and moreover to tackle the issue of the STEM skills shortage, we have designed a self-contained lesson to introduce youths to this topic. It is modularised into three parts, beginning with using light to communicate Morse code, and then covering advanced themes such as multiplexing and fibre guidance based on total internal reflection. The modules can be taught sequentially or individually depending on educational level. They emphasise a more phenomenological than theoretical approach and include hands-on activities using easily obtainable materials. We outline the lesson and pedagogical guidelines for classroom settings, as well as evaluate actual classes run. This lesson can be flexibly implemented in formal classes or through educational outreach programmes
Dataset for High-birefringence direct UV-written waveguides for use as heralded single-photon sources at telecommunication wavelengths
No full textCharacterisation data for the UV-written waveguide devices reported in "High-birefringence direct UV-written waveguides for use as heralded single-photon sources at telecommunication wavelengths," Optica (2018).</span
Taking quantum entanglement out of the lab
No full textThe Networked Quantum Information Technologies hub (NQIT) is one of the quantum hubs of the UK's flagship scheme, bringing together academia, industry and government. The Optical Engineering and Quantum Photonics group at the University of Southampton's Optoelectronics Research Centre have developed an interactive demonstrator of a key device within NQIT to bring quantum photonics technologies to a wider audience. The system was exhibited at the 2017 UK Quantum Showcase in London to an audience of industry and government. It also featured as part of the Quantum City stand at the 2018 Cheltenham science festival, one of the UK's leading annual science events
Low-loss wavelength-selective integrated waveguide coupler based on tilted Bragg gratings
No full textWe propose and investigate numerically a new kind of integrated optical waveguide coupler. Two waveguides with tilted Bragg gratings couple selectively to a discrete counter-propagating cladding mode which acts as an intermediary to transfer power between the waveguides. This gives a highly versatile platform that can act as a low-loss coupler with arbitrary coupling ratio between 0 and 100%, as a narrowbandwidth wavelength filter, and as a phase-selective switch that transmits two light waves of a fixed relative phase but reflects the orthogonal phase within a single device
Tilted Bragg gratings in integrated optical fiber
No full textIn this paper, the first successful demonstration of a short period tilted Bragg grating in integrated optical fiber is reported through the observation of resonance features in the reflection spectrum from a 4.98° tilted grating
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Fabricating a prototype spectrometer using a large-angle direct UV-written chirped tilted grating
No full textA prototype planar waveguide spectrometer is fabricated with a 45° direct UV-written grating and a chirp of 140 nm. The grating focus translates by 1-2 μm/nm of input wavelength tuning, over a bandwidth of more than 200 nm.</p
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