| 1. |
- Argillander, Joakim, et al.
(author)
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A tunable quantum random number generator based on a fiber-optical Sagnac interferometer
- 2022
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In: Journal of Optics. - Bristol, United Kingdom : Institute of Physics Publishing (IOPP). - 2040-8978 .- 2040-8986. ; 24:6
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Journal article (peer-reviewed)abstract
- Quantum random number generators (QRNGs) are based on naturally random measurementresults performed on individual quantum systems. Here, we demonstrate a branching-pathphotonic QRNG implemented using a Sagnac interferometer with a tunable splitting ratio. Thefine-tuning of the splitting ratio allows us to maximize the entropy of the generated sequence ofrandom numbers and effectively compensate for tolerances in the components. By producingsingle-photons from attenuated telecom laser pulses, and employing commercially-availablecomponents we are able to generate a sequence of more than 2 gigabytes of random numberswith an average entropy of 7.99 bits/byte directly from the raw measured data. Furthermore, oursequence passes randomness tests from both the NIST and Dieharder statistical test suites, thuscertifying its randomness. Our scheme shows an alternative design of QRNGs based on thedynamic adjustment of the uniformity of the produced random sequence, which is relevant forthe construction of modern generators that rely on independent real-time testing of itsperformance.
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| 2. |
- Balliu, Enkeleda, PhD student, et al.
(author)
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Single-frequency, pulsed Yb3+-doped multicomponent phosphate power fiber amplifier
- 2020
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In: Journal of Optics. - : Institute of Physics Publishing (IOPP). - 2040-8978 .- 2040-8986. ; 22:11
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Journal article (peer-reviewed)abstract
- High-power, single-frequency, pulsed fiber amplifiers are required in light detection and ranging, coherent laser detection, and remote sensing applications to reach long range within a short acquisition time. However, the power-scaling of these amplifiers is limited by nonlinearities generated in the optical fibers, in particular by stimulated Brillouin scattering (SBS). In this regard, the use of multicomponent phosphate glasses maximizes the energy extraction and minimizes nonlinearities. Here, we present the development of a single-stage, hybrid, pulsed fiber amplifier using a custom-made multicomponent Yb-doped phosphate fiber. The performance of the phosphate fiber was compared to a commercial Yb-doped silica fiber. While the latter showed SBS limitation at nearly 6.5 kW for 40 cm length, the maximum achieved output peak power for the multicomponent Yb-doped phosphate fiber was 11.7 kW for 9 ns pulses using only 20 cm with no sign of SBS.
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| 3. |
- Forssén, Clayton, et al.
(author)
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An optical pascal in Sweden
- 2022
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In: Journal of Optics. - : IOP Publishing Ltd. - 2040-8978 .- 2040-8986. ; 24:3
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Journal article (peer-reviewed)abstract
- By measuring the refractivity and the temperature of a gas, its pressure can be assessed from fundamental principles. The highest performing instruments are based on Fabry-Perot cavities where a laser is used to probe the frequency of a cavity mode, which is shifted in relation to the refractivity of the gas in the cavity. Recent activities have indicated that such systems can demonstrate an extended uncertainty in the 10 ppm (parts-per-million or 10-6) range. As a means to reduce the influence of various types of disturbances (primarily drifts and fluctuations) a methodology based on modulation, denoted gas modulation refractometry (GAMOR), has recently been developed. Systems based on this methodology are in general high-performance, e.g. they have demonstrated precision in the sub-ppm range, and they are sturdy. They can also be made autonomous, allowing for automated and unattended operation for virtually infinite periods of time. To a large degree, the development of such instruments depends on the access to modern photonic components, e.g. narrow line-width lasers, electro-and acousto-optic components, and various types of fiber components. This work highlights the role of such modern devices in GAMOR-based instrumentation and provides a review on the recent development of such instruments in Sweden that has been carried out in a close collaboration between a research institute and the Academy. It is shown that the use of state-of-the-art photonic devices allows sturdy, automated and miniaturized instrumentation that, for the benefit of industry, can serve as standards for pressure and provide fast, unattended, and calibration-free pressure assessments at a fraction of the present cost. © 2022 The Author(s).
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| 4. |
- Mavrogordatos, Themistoklis K.
(author)
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Telling emissions apart in a multiphoton resonance : visualizing a conditional evolution
- 2023
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In: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 25:2
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Journal article (peer-reviewed)abstract
- We find that the phase-space representation of the electromagnetic field inside a driven cavity strongly coupled to a two-level atom can be employed to distinguish photon emissions along a ladder of dressed states sustaining a two-photon resonance. The emissions are told apart by means of the different quantum beats generated by the conditional states they prepare. Sample quantum trajectories explicitly reveal the difference in the transient due to the initial condition, in a background set by the Jaynes–Cummings spectrum and revealed by the strong-coupling limit. Their ensemble-averaged evolution is tracked for a time period similar to that waited for the loss of a next photon as the maximum non-exclusive probability, indicated by the peak of the intensity correlation function.
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| 5. |
- Rossi, Stefano, et al.
(author)
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Highly reflective optical nanocavities for structural coloration by combining broadband absorber and Fabry-Perot effects
- 2021
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In: Journal of Optics. - : IOP PUBLISHING LTD. - 2040-8978 .- 2040-8986. ; 23:1
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Journal article (peer-reviewed)abstract
- Reflective structural colors are of interest for many applications as alternatives to dyes and pigments and many different solutions have been proposed. The ideal systems should provide high reflectance efficiency while keeping good chromaticity and offering tunability throughout the visible spectral range. It is challenging to achieve such combined features with a simple single structure. Here we address this challenge using a concept that combines the Fabry-Perot effect with a broadband absorbing layer. Our easy-to-fabricate structures form highly reflective optical nanocavities with improved chromaticity throughout the visible compared with the two separate concepts. The addition of an additional cavity layer and a transparent top coating further improves the chromaticity and allows the formation of black surfaces.
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| 6. |
- Tapani, Tlek, et al.
(author)
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Vortex plate retarder-based approach for the generation of sub-20 fs light pulses carrying orbital angular momentum
- 2024
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In: Journal of Optics. - : Institute of Physics (IOP). - 2040-8978 .- 2040-8986. ; 26:4
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Journal article (peer-reviewed)abstract
- We use a vortex retarder-based approach to generate few optical cycles light pulses carrying orbital angular momentum (OAM) (known also as twisted light or optical vortex) from a Yb:KGW oscillator pumping a noncollinear optical parametric amplifier generating sub-10 fs linearly polarized light pulses in the near infrared spectral range (central wavelength 850 nm). We characterize such vortices both spatially and temporally by using astigmatic imaging technique and second harmonic generation-based frequency resolved optical gating, respectively. The generation of optical vortices is analyzed, and its structure reconstructed by estimating the spatio-spectral field and Fourier transforming it into the temporal domain. As a proof of concept, we show that we can also generate sub-20 fs light pulses carrying OAM and with arbitrary polarization on the first-order Poincaré sphere.
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| 7. |
- Yue, Shichao, et al.
(author)
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Imaging through a multimode optical fiber with principal component analysis and a variational autoencoder
- 2024
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In: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 26:4
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Journal article (peer-reviewed)abstract
- Imaging through the multi-mode fiber (MMF) becomes an attractive approach for gaining visual access to confined spaces. However, current imaging techniques through a MMF still encounter challenges including modal dispersion, complex wave-front shaping mechanism, and expensive light sources and modulations. This work proposed a cost-efficient setup with three light-emitting diodes as the illumination light source (including red, green, and blue light) and a hybrid model including the principal component analysis and a variational auto-encoder (PCAVAE) for reconstructing the transmitted images. The reconstructed images demonstrate high fidelity compared with their ground truth images. The average similarity index value of the reconstructed images is as high as 0.99. Experimental works indicated that the proposed approach was capable of rejecting 10% white noise in the imaging process. The proposed triple-color illumination method paves a cost-effective way of transmitting images through an MMF. The PCAVAE model established in this work demonstrates great potential for processing scrambled images transmitted by the MMF.
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| 8. |
- Piccardo, M, et al.
(author)
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Roadmap on multimode light shaping
- 2022
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In: JOURNAL OF OPTICS. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 24:1
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Journal article (other academic/artistic)abstract
- Our ability to generate new distributions of light has been remarkably enhanced in recent years. At the most fundamental level, these light patterns are obtained by ingeniously combining different electromagnetic modes. Interestingly, the modal superposition occurs in the spatial, temporal as well as spatio-temporal domain. This generalized concept of structured light is being applied across the entire spectrum of optics: generating classical and quantum states of light, harnessing linear and nonlinear light-matter interactions, and advancing applications in microscopy, spectroscopy, holography, communication, and synchronization. This Roadmap highlights the common roots of these different techniques and thus establishes links between research areas that complement each other seamlessly. We provide an overview of all these areas, their backgrounds, current research, and future developments. We highlight the power of multimodal light manipulation and want to inspire new eclectic approaches in this vibrant research community.
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