Four-mode multiplexing and manipulation technologies are reviewed in the context of space-division multiplexing (SDM) optical communication systems. These are multiplane light conversion (MPLC), ...fused fiber devices, such as photonic lanterns and tapered fiber bundles, 3-D waveguides fabricated using ultrafast laser inscription, and free-space imaging systems. Each device has its unique strengths and use cases. MPLC can create very complex transformations between two arbitrary sets of spatial modes and leverages mature gray-scale lithographic techniques. Photonic lanterns and tapered fiber bundles are all-fiber devices that can convert beams on single-mode fiber inputs into spatial modes. The all-fiber construction leads to very low losses and high-power handling. 3-D waveguides are inscribed into a glass block using ultrashort lasers and can arbitrarily route light in 3-D. Finally, free-space systems using lenses can also relay many multicore and multimode beams through a single free-space device, such as a thin film filter or an optical isolator. These four technologies have enabled hero transmission experiments in the multimode, multicore, and multimode fiber.
Air clad Photonic Lanterns Mathew, Neethu Mariam; Gruner-Nielsen, Lars; Galili, Michael ...
2022 IEEE Photonics Society Summer Topicals Meeting Series (SUM),
2022-July
Conference Proceeding
Design and fabrication of air-clad photonic lanterns with purity higher than 15 dB for the two LP modes is presented. An LP 02 mode converter is fabricated using the same principle and the LP 02 mode ...purity is measured above 10 dB over C and L hands.
As SDG7-related interventions seek to transform access to clean energy, this paper presents an analysis of both a previous transformative intervention (Lighting Africa) and a theoretical approach to ...understanding how such transformations can be achieved in the Global South (socio-technical innovation system, STIS, building). The paper makes four contributions. First, it tests the extent to which the STIS-building concept is useful in understanding and conceptualising how Lighting Africa transformed the market for solar lanterns in Kenya from an estimated market size of 29,000 lamps in 2009 to one where 680,000 Lighting Africa certified lamps were sold in Kenya by the end of the Programme in 2013. Second, it presents the most in-depth analysis of Lighting Africa that we are aware of to date. Third, it presents a conceptual framework that illustrates the Lighting Africa approach, providing a framework for future policy interventions aiming to transform access to clean energy technologies in the Global South. Fourth, it reflects on weaknesses in the STIS approach. In particular, these include a need to better attend to: the gendered implications of interventions (and social justice more broadly); implications of different scales of technologies; value accumulation and the extent to which interventions benefit indigenous actors and local economies; and the political and economic implications of any intervention and its distribution of benefits.
Photonic technologies offer numerous advantages for astronomical instruments such as spectrographs and interferometers owing to their small footprints and diverse range of functionalities. Operating ...at the diffraction-limit, it is notoriously difficult to efficiently couple such devices directly with large telescopes. We demonstrate that with careful control of both the non-ideal pupil geometry of a telescope and residual wavefront errors, efficient coupling with single-mode devices can indeed be realised. A fibre injection was built within the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument. Light was coupled into a single-mode fibre operating in the near-IR (J − H bands) which was downstream of the extreme adaptive optics system and the pupil apodising optics. A coupling efficiency of 86% of the theoretical maximum limit was achieved at 1550 nm for a diffraction-limited beam in the laboratory, and was linearly correlated with Strehl ratio. The coupling efficiency was constant to within <30% in the range 1250–1600 nm. Preliminary on-sky data with a Strehl ratio of 60% in the H-band produced a coupling efficiency into a single-mode fibre of ~50%, consistent with expectations. The coupling was >40% for 84% of the time and >50% for 41% of the time. The laboratory results allow us to forecast that extreme adaptive optics levels of correction (Strehl ratio >90% in H-band) would allow coupling of >67% (of the order of coupling to multimode fibres currently) while standard levels of wavefront correction (Strehl ratio >20% in H-band) would allow coupling of >18%. For Strehl ratios <20%, few-port photonic lanterns become a superior choice but the signal-to-noise, and pixel availability must be considered. These results illustrate a clear path to efficient on-sky coupling into a single-mode fibre, which could be used to realise modal-noise-free radial velocity machines, very-long-baseline optical/near-IR interferometers and/or simply exploit photonic technologies in future instrument design.
Invited for the cover of this issue is the group of Yuanhua Wang at Sichuan University. The image depicts the reported dirhodium complexes depicted as Chinese lanterns. Read the full text of the ...article at 10.1002/chem.201905855.
“In this study, the direct azidation of benzaldehydes catalyzed by the dirhodium(II) catalysts was successfully achieved by the slow generation of the putative one‐electron oxidative intermediate Rh2(II,III)N3. Such a highly efficient direct azidation provides a more concise route for the synthesis of some important bioactive compounds.” Read more about the story behind the cover in the Cover Profile and about the research itself on page 6805 ff. (DOI: 10.1002/chem.201905855).
The development of new synthetic approaches to the 1,4-benzodiazepine ring system and their further elaboration have provided access to a broad range of functionalized derivatives. In this review an ...attempt has been made to summarize those synthetic strategies involved for the synthesis of privileged scaffold 1,4-benzodiazepine over time.
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