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| 2. |
- Arnold, Cord, et al.
(author)
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Nonlinear Bessel vortex beams for applications
- 2015
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 48:9
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Journal article (peer-reviewed)abstract
- We investigate experimentally and numerically the nonlinear propagation of intense BesselGauss vortices in transparent solids. We show that nonlinear Bessel-Gauss vortices preserve all properties of nonlinear Bessel-Gauss beams while their helicity provides an additional control parameter for single-shot precision micro structuring of transparent solids. For sufficiently large cone angle, a stable hollow tube of intense light is formed, generating a plasma channel whose radius and density are increasing with helicity and cone angle, respectively. We assess the potential of intense Bessel vortices for applications based on the generation of hollow plasma channels.
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| 3. |
- Houard, Aurélien, et al.
(author)
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Laser-guided lightning
- 2023
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In: Nature Photonics. - : Springer Nature. - 1749-4885 .- 1749-4893. ; 17:3, s. 231-235
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Journal article (peer-reviewed)abstract
- Lightning discharges between charged clouds and the Earth's surface are responsible for considerable damages and casualties. It is therefore important to develop better protection methods in addition to the traditional Franklin rod. Here we present the first demonstration that laser-induced filaments-formed in the sky by short and intense laser pulses-can guide lightning discharges over considerable distances. We believe that this experimental breakthrough will lead to progress in lightning protection and lightning physics. An experimental campaign was conducted on the Santis mountain in north-eastern Switzerland during the summer of 2021 with a high-repetition-rate terawatt laser. The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. The guiding of negative lightning leaders by laser filaments was corroborated in three other instances by very-high-frequency interferometric measurements, and the number of X-ray bursts detected during guided lightning events greatly increased. Although this research field has been very active for more than 20 years, this is the first field-result that experimentally demonstrates lightning guided by lasers. This work paves the way for new atmospheric applications of ultrashort lasers and represents an important step forward in the development of a laser based lightning protection for airports, launchpads or large infrastructures. A terawatt laser filament is shown to be able to guide lightning over a distance of 50 m in field trials on the Santis mountain in the Swiss Alps.
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| 4. |
- Steinhauer, Stephan, et al.
(author)
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Rydberg excitons in Cu2O microcrystals grown on a silicon platform
- 2020
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In: Communications Materials. - : Springer Nature. - 2662-4443. ; 1:1
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Journal article (peer-reviewed)abstract
- Cuprous oxide (Cu2O) is a semiconductor with large exciton binding energy and significant technological importance in applications such as photovoltaics and solar water splitting. It is also a superior material system for quantum optics that enabled the observation of intriguing phenomena, such as Rydberg excitons as solid-state analogue to highly-excited atomic states. Previous experiments related to excitonic properties focused on natural bulk crystals due to major difficulties in growing high-quality synthetic samples. Here, the growth of Cu2O microcrystals with excellent optical material quality and very low point defect levels is presented. A scalable thermal oxidation process is used that is ideally suited for integration on silicon, demonstrated by on-chip waveguide-coupled Cu2O microcrystals. Moreover, Rydberg excitons in site-controlled Cu2O microstructures are shown, relevant for applications in quantum photonics. This work paves the way for the wide-spread use of Cu2O in optoelectronics and for the development of novel device technologies. Cu2O is of great interest for its excitonic properties, yet challenges in its fabrication means that most experiments focus on naturally occurring samples. Here, scalable thermal oxidation is reported for the growth of Cu2O with low-defect content, allowing the observation of Rydberg excitons.
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| 5. |
- Versteegh, Marijn A. M., et al.
(author)
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Giant Rydberg excitons in Cu2O probed by photoluminescence excitation spectroscopy
- 2021
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In: PHYSICAL REVIEW B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 104:24
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Journal article (peer-reviewed)abstract
- Rydberg excitons are, with their ultrastrong mutual interactions, giant optical nonlinearities, and very high sensitivity to external fields, promising for applications in quantum sensing and nonlinear optics at the singlephoton level. To design quantum applications it is necessary to know how Rydberg excitons and other excited states relax to lower-lying exciton states. Here, we present photoluminescence excitation spectroscopy as a method to probe transition probabilities from various excitonic states in cuprous oxide. We show giant Rydberg excitons at T = 38 mK with principal quantum numbers up to n = 30, corresponding to a calculated diameter of 3 mu m.
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