1,720,999 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
Dataset for Modular and extensible lesson on optical fibre communication for youths
No full textThis dataset supports the publication: Nicholas H. L. Wong et al (2019). Modular and extensible lesson on optical fibre communication for youths. Physics Education</span
Optical beam splitting and switching based on arrays of tilted Bragg gratings in planar waveguides
No full textModular 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
Integrated polarizing coupler based on tilted gratings
No full textWe report the first demonstration of an integrated polarizing coupler based on tilted gratings operating in the C-band with a TE-TM extinction ratio in the out-coupled port in excess of 17 dB
Integrated polarizer based on 45º tilted gratings
No full textWe report the first integrated implementation of a polarizer based on the use of 45° tilted gratings in planar waveguides. The waveguides and gratings are fabricated by direct UV writing in a hydrogenated germanium-doped silica-on-silicon chip. We experimentally demonstrate a polarization extinction ratio per unit length of 0.25 dB mm−1 with a modelled wavelength dependence smaller than 0.3 dB for a 20 mm device over the C band from 1530–1570 nm. We also present a novel numerical study and analytical description of the architecture that are in good agreement with each other and the experimental data
Planar waveguide coupler based on tilted Bragg gratings and a discrete cladding mode
No full textWe have recently developed a new technology for direct UV-written integrated waveguide circuits. In particular, we exploit tilted Bragg gratings to couple light between parallel channel waveguides, which potentially allows for wavelength and polarisation selective optical coupling. A polarising coupler between two waveguides with close to 30 dB polarisation extinction ratio has already been demonstrated experimentally based on gratings with a tilt angle of 45º [1]. However, this device exhibited a waveguide-to-waveguide loss of 10.5 dB, which even in theory cannot be reduced to less than 3 dB because of light being lost into the continuum of radiation modes.Here we investigate theoretically and numerically an improved design with tailored cladding modes that overcomes this intrinsic loss. In this case the substrate is structured into a wide ridge waveguide, e.g. by micromachining two channels separating the ridge from the rest of the substrate. Two parallel single-mode waveguides containing tilted Bragg gratings are then written into this ridge. Light is now coupled between the two waveguides utilising the modal structure of the ridge instead of the continuum of modes in an unstructured substrate. By tailoring the period and tilt angle of the gratings, forward and/or backward propagating ridge modes can be coupled and the grating bandwidth can be adjusted to form a wavelength selective coupler with improved coupling efficiency.We use coupled mode theory to simulate the complete system of the two waveguides coupled to the full set of ridge modes as an N-by-N coupler using the weakly guiding approximation, where the coupling strength of the gratings is calculated from spatial overlaps of modes obtained by finite element simulations. In the case of weak gratings, we find that the effect of non-resonantly coupled modes can be neglected. This leads to a simplified model of only three coupled modes, the two waveguide modes and a single ridge mode. By using a counter-propagating ridge mode and introducing a slight wavelength detuning away from the grating resonance we are able to switch between two operation modes of the device. In one solution, the power in the input waveguide decays exponentially with propagation distance. The other solution has periodic oscillations as power is exchanged between the two waveguides. In the latter case, the power exchange reaches a theoretical maximum efficiency of 100%.Finally, we will present the validation of our coupled mode theory model by finite element simulations in two dimensions and further details of an analytic solution that fully describes the simplified three-mode system. This will allow us to quickly design and optimise devices for subsequent fabrication and experimental demonstration.<br/
Taking local optics outreach abroad for IYL 2015: administrative and logistical challenges and strategies
No full textThe Lightwave Roadshow is an outreach program run by research students at the University of Southampton, UK, that seeks to educate and inspire young students with optics, through conducting workshops in local schools and exhibiting at local and regional educational fairs. Adopting a hands-on philosophy enabled by an extensive collection of experimental optical demonstrations, Lightwave aims to promote scientific interest and indirectly address the global STEM skills shortage. While Lightwave has become a well-established program in local schools since its inception in 1998, 2015 included an unprecedented number of overseas activities. Inspired by the International Year of Light and Light-based Technologies (IYL 2015), Lightwave organized a school workshop in a foreign country (Singapore) as well as exhibited at major events, including the IYL 2015 opening ceremony in France, which marked the first time that the roadshow used UK school students to deliver outreach activities beyond the UK. These recent successful overseas projects have encouraged the outreach team to continue expanding the reach of the roadshow internationally. Of particular note is the involvement of Lightwave at academic conferences, where experiences and best practices can be shared among outreach ambassadors from different programs, student chapters, universities, and organizations. This paper provides a review of these activities, and identifies the administrative and practical challenges of bringing a local outreach program abroad and some strategies to overcome them. We also outline our travel suite of experimental demonstration kit, a portable selection from our main equipment inventory. This won the recent OSA ‘IYL-To-Go’ student competition
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
From school classes to UNESCO: IYL-enabled environments for tackling the STEM skills shortage through student-led outreach
No full textThe accepted industrial skills shortage in the subjects of science, technology, engineering and mathematics (STEM) in the United Kingdom has led to an increasing drive for universities to work with a wider pool of potential students. One contributor to this drive is the Lightwave Roadshow, a photonics-focused outreach program run by postgraduate students from the University of Southampton. The program has benefitted from the unique platform of the International Year of Light (IYL) 2015 for the development and support of hands-on and interactive outreach activities. In this report we review Lightwave activities facilitated by IYL that focused on widening participation for students aged 6 to 18 years from a multitude of societal categories; the roadshow has directly benefitted from the significance and investment into the IYL in conjunction with university recruitment strategies, local schools and the support of international organizations such as SPIE and OSA. Lightwave has used the foundation of the IYL to provide a wide range of activities for over 1,200 UK students in 53 different schools; the assessment tools used to measure learning outcomes, reach and impact are also discussed. The program’s activities have been developed to make younger age groups the center of the outreach activity and create an environment which encourages youth pursuit of optics and science from a grassroots level upwards; to illustrate this we will outline a Lightwave project endorsed by the IYL steering committee to permit two 6th form students to attend the IYL opening ceremony in Paris
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