by Eric J. Stanton, Peter Tønning, Emil Z. Ulsig et al.

• This paper published in Scientific Reports presents the development of a compact, solid-state far-UVC laser source leveraging a chip-scale pump laser and advanced nonlinear materials. By optimizing Cherenkov phase-matching in a silicon nitride (SiN) waveguide bonded to a beta barium borate (BBO) crystal, the device efficiently converts blue laser light to far-UVC wavelengths. The robust design allows for high-yield production and broad wavelength tunability, with potential applications in disinfection, non-line-of-sight communication, and Raman spectroscopy. This innovative approach not only reduces the size and cost of far-UVC lasers but also opens up new possibilities for their widespread use in various scientific and industrial fields.
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by Simon Thorndahl Thomsen et al.

• Published in Optics Letters, this paper demonstrates a refined way to extract the frequency noise (FN) spectrum of lasers by tailoring the delay in a conventional delayed self-heterodyne setup to sub-coherence lengths. The method achieves direct proportionality between electrical spectrum analyzer traces and the FN spectrum, which provide the intrinsic linewidth of the lasers. This proposed method is validated by comparing the FN spectrum with that obtained from a commercial frequency noise analyzer. The method provides a cost-effective alternative for FN measurements, which also requires minimal post-processing as compared to the state-of-the-art.
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by Mikkel T. Hansen et al.

• Published in Frontiers in Photonics, this paper reports on a design of a double-ridge waveguide for efficient and robust second-harmonic generation (SHG) using the thin-film lithium-niobate-on-insulator (LNOI) platform. Perfect phase matching (PhM) is achieved between the fundamental waveguide mode at 1,550 nm and a higher-order mode at the second harmonic. The fabrication tolerances of the PhM condition are simulated using a finite-difference method mode solver, and conversion efficiencies as high as 3.92 W⁻¹ are obtained for a 1-cm long waveguide. This design allows access to the largest element of the second-order nonlinear susceptibility tensor, and represents a scalable alternative to waveguides based on periodically-poled lithium niobate (PPLN). The design has the potential for generating pairs of entangled photons in the infrared C-band by spontaneous parametric down-conversion (SPDC).
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by Emil Zanchetta Ulsig et al.

• Published in the IEEE Photonics Conference, this paper proposes a design for second-order sum, difference, and spontaneous parametric conversion from InGaP-on-insulator waveguides. Experimental results of these nonlinear effects are measured from similar integrated waveguides in AlGaAs- and GaAs-on-insulator, highlighting the strengths of each platform and the prospects of implementing with InGaP-on-insulator.
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by Ying Wang et al.

• Published in npj Quantum Information, this paper presents a breakthrough in quantum information technology by demonstrating the integration of a deterministic photon source with a programmable silicon-nitride photonic circuit. This integration is pivotal for scalable quantum networks and quantum computing. Single-photon generation is successfully combined with an advanced photonic chip, enhancing the control and manipulation of quantum states at the photon level. This development opens new avenues for high-fidelity quantum information processing and secure communication systems, marking a significant step towards practical quantum technologies.
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by Magnus Linnet Madsen et al.

• Mid-infrared (MIR) lasers are pivotal in environmental monitoring, industrial gas sensing, free-space telecommunication, and defense applications due to their unique absorption characteristics in the 1.4-10 µm range. This paper published in the Journal of the Optical Society of America B explores the design and simulation of a novel AlGaAs-on-silicon waveguide for efficient difference-frequency generation (DFG) at 2.3 µm. Using a tunable pump in the near-infrared and a tunable idler in the C-band, the waveguide achieves perfect phase matching through form birefringence, resulting in high nonlinear conversion efficiencies. The proposed waveguide, with optimized dimensions, promises a significant signal output power and a wide tunable range, advancing the potential for compact and versatile MIR light sources.
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by Fabian Ruf et al.

• This paper published in the Journal of Lightwave Technology presents groundbreaking advancements in the design of ultra-fast, low-loss all-optical switches on silicon nitride, essential for integrated single-photon applications. Using a novel traveling-wave model, it meticulously analyzes two ring resonator-based switches, highlighting their potential in achieving near-perfect signal transmission with minimal energy requirements. The study showcases innovative solutions like chirped Gaussian pulses to enhance performance, and offers a comprehensive framework for future development, promising significant strides in quantum computing and photonic networks with insertion losses as low as 0.1 dB.
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by Atefeh Shadmani et al.

• This paper published in Optics Express presents a breakthrough in quantum photonic integrated circuits (QPICs) by demonstrating GaAs waveguides with embedded quantum dots on a silicon substrate. Utilizing a novel adhesive bonding technique, high-quality fabrication is achieved, preserving excellent optical properties and single-photon emission capabilities. This integration not only maintains low-noise, high-efficiency photon generation but also opens the door to combining GaAs technology with various photonic platforms, marking a significant step towards scalable and hybrid QPICs for advanced quantum applications.
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by Emil Ulsig et al.

• The paper published in Frontiers in Photonics explores the design and optimization of a novel single-photon source for quantum applications using difference frequency generation (DFG) in zinc-blende materials, specifically focusing on AlGaAs. Aimed at converting single-photons emitted by indium arsenide (InAs) quantum dots at 930 nm to the telecom C-band at 1550 nm, the study highlights the advantages of AlGaAs over conventional lithium niobate (LN) due to its higher second-order nonlinearity and better optical confinement. By integrating III-V materials on silica with a silicon substrate, the proposed design significantly enhances conversion efficiency, essential for large-scale quantum networks. Detailed simulations demonstrate efficient phase-matching and high conversion efficiency with relatively low optical power and short waveguide lengths, marking a substantial advancement in the development of practical, integrated quantum photonic devices.
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by Emil Ulsig and Peter Tønning

• The COVID-19 pandemic underscored the importance of sanitizing surfaces and wearing masks, but are these methods still the best? According to this Medicoteknik publication, an innovative approach using ultraviolet light offers ultraviolet light presents a promising alternative for disinfecting both surfaces and air. Traditional UV light at 254 nm effectively neutralizes pathogens but is harmful to humans. However, "Far-UVC" light, operating at 200-230 nm, offers a safe solution. This technology, using krypton chloride excimer lamps to emit light at 222 nm, can disinfect spaces while people are present. Developed by Aarhus-based UV Medico, Far-UVC lamps have been installed in hospitals, workplaces, and public spaces, proving effective in reducing the spread of infectious diseases without harming human health. This innovation could significantly mitigate the transmission of current and future pathogens, including common illnesses like flu and colds.
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by TBC et al.

• Published in TBC, this paper TBC