| 1. |
- Brown, P.G., et al.
(författare)
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The Hamburg meteorite fall : Fireball trajectory, orbit, and dynamics
- 2019
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Ingår i: Meteoritics and Planetary Science. - : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 54:9, s. 2027-2045
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Tidskriftsartikel (refereegranskat)abstract
- The Hamburg (H4) meteorite fell on 17 January 2018 at 01:08 UT approximately 10 km north of Ann Arbor, Michigan. More than two dozen fragments totaling under 1 kg were recovered, primarily from frozen lake surfaces. The fireball initial velocity was 15.83 ± 0.05 km s−1, based on four independent records showing the fireball above 50 km altitude. The radiant had a zenith angle of 66.14 ± 0.29° and an azimuth of 121.56 ± 1.2°. The resulting low inclination (<1°) Apollo‐type orbit has a large aphelion distance and Tisserand value relative to Jupiter (Tj) of ~3. Two major flares dominate the energy deposition profile, centered at 24.1 and 21.7 km altitude, respectively, under dynamic pressures of 5–7 MPa. The Geostationary Lightning Mapper on the Geostationary Operational Environmental Satellite‐16 also detected the two main flares and their relative timing and peak flux agree with the video‐derived brightness profile. Our preferred total energy for the Hamburg fireball is 2–7 T TNT (8.4–28 × 109 J), which corresponds to a likely initial mass in the range of 60–225 kg or diameter between 0.3 and 0.5 m. Based on the model of Granvik et al. (2018), the meteorite originated in an escape route from the mid to outer asteroid belt. Hamburg is the 14th known H chondrite with an instrumentally derived preatmospheric orbit, half of which have small (<5°) inclinations making connection with (6) Hebe problematic. A definitive parent body consistent with all 14 known H chondrite orbits remains elusive.
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| 4. |
- Mazur, Mikael, 1990, et al.
(författare)
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High spectral efficiency coherent superchannel transmission with soliton microcombs
- 2021
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 39:13, s. 4367-4373
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Tidskriftsartikel (refereegranskat)abstract
- Spectral efficiency (SE) is one of the key metrics for optical communication networks. An important building block for its maximization are optical superchannels, channels that are composed of several subchannels with an aggregate bandwidth larger than the bandwidth of the detector electronics. Superchannels which are routed through the network as a single entity, together with flex-grid routing, allow to more efficiently utilize available bandwidth and eliminate the guard-bands between channels, thus increasing spectral efficiency. In contrast to traditional wavelength division multiplexing (WDM) channels, subchannel spacing and thus superchannel SE is governed by the linewidth and stability of the frequency spacing of the transmitter lasers. Integrated optical frequency combs, particulary the parametrically generated so-called microcombs, which provide optical lines on a fixed frequency grid are a promising solution for low power superchannel laser sources that allow to minimize the SE loss from suboptimal channel spacing. However, it is extremely challenging to realize micro-combs with sufficient line power, coherence and line spacing that is compatible with electronic bandwidths. Because the line-spacing generated by most devices is above 40 GHz, demonstrations often rely on additional electro-optic frequency shifter or divider stages to avoid digital-to-analog-converter (DAC) performance degradation when operating at high symbol rates. Here we demonstrate a 50-line superchannel from a single 22 GHz line spacing soliton microcomb. We demonstrate 12 Tb/s throughput with > 10 bits/s/Hz SE efficiency after 80 km transmission and 8 Tb/s throughput (SE > 6 bits/s/Hz) after 2100 km, proving the feasibility and benefits of generating high signal quality, broadband waveforms directly from the output of a micro-scale device with a symbol rate close to the comb repetition rate.
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| 5. |
- Mazur, Mikael, 1990, et al.
(författare)
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High spectral efficiency superchannel transmission using a soliton microcomb
- 2019
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Ingår i: IET Conference Publications. ; 2019:CP765
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Konferensbidrag (refereegranskat)abstract
- We demonstrate transmission of a 52 channel superchannel using an optimized 22.1 GHz-spaced soliton microcomb. Enabling a record spectral efficiency of >10 bits/s/Hz after 80 km and 6.1 bits/s/Hz after 3000 km using a microcomb. Our results demonstrate that chip-scale combs can achieve performance directly comparable to bulk-optic frequency combs.
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| 6. |
- Choutagunta, Karthik, et al.
(författare)
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Modal Dynamics in Spatially Multiplexed Links
- 2019
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Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : OSA. - 2162-2701.
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Konferensbidrag (refereegranskat)abstract
- We investigate the vibration sensitivity of spatially multiplexed links by measuring the mode-coupling dynamics of a four-core coupled-core fiber and a reference single-mode fiber. We show that the speed of dynamics increases with mode count.
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| 7. |
- Deriushkina, Ekaterina, 1992, et al.
(författare)
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Characterisation of a Coupled-Core Fiber Using Dual-Comb Swept-Wavelength Interferometry
- 2021
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Ingår i: 2021 European Conference on Optical Communication, ECOC 2021.
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Konferensbidrag (refereegranskat)abstract
- We present a measurement of the transfer matrix of a coupled three-core fiber using a novel combination of swept-wavelength interferometry and dual-comb spectroscopy capable of measuring 1 THz bandwidth with a frequency resolution of 50 kHz with only a 25 GHz laser sweep.
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| 8. |
- Fontaine, Nicolas K., et al.
(författare)
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Digital turbulence compensation of free space optical link with multimode optical amplifier
- 2019
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Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2019:CP765
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Konferensbidrag (refereegranskat)abstract
- We demonstrate digital turbulence compensation using a 12-spatial mode digital coherent receiver with a multimode preamplifier that provides a 6-dB sensitivity improvement. This combination acts similarly to ideal lossless adaptive optics. Coherent superposition of 12 spatial-modes reduced median BER from 0.1 to 1×10-5 compared to traditional single-mode detection.
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| 9. |
- Huang, Yetian, et al.
(författare)
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Optical Broadcasting Employing Incoherent And Low-Coherence Spatial Modes for Bi-Directional Optical Wireless Communications
- 2021
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 39:3, s. 833-838
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Tidskriftsartikel (refereegranskat)abstract
- We introduce recently developed space division multiplexing (SDM)-associated technologies into optical wireless communications (OWC) and propose to use incoherent and low-coherence spatial modes to realize optical broadcasting with reliable performance by mitigating coherent interference. We experimentally demonstrate reconfigurable optical beam steering using a programmable multi-plane light conversion (MPLC)-based mode multiplexer (MMUX) and realize point-to-multi-point optical wireless communications with low-loss up-link optical beam combining and reach extension using multimode fiber (MMF). Both incoherent and low-coherence spatial modes can be generated employing the cost-efficient components such as multimode vertical cavity surface emitting laser (MM-VCSEL) and broadband amplified spontaneous emission (ASE) noise source.
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| 10. |
- Mazur, Mikael, 1990, et al.
(författare)
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Characterization of Long Multi-Mode Fiber Links using Digital Holography
- 2019
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; Part F160-OFC 2019
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Konferensbidrag (refereegranskat)abstract
- We propose to use digital holography to characterize long multi-mode fiber links. A four segment 26.5km fiber span supporting 45 spatial modes is analyzed, showing the evolution of both mode-dependent loss and cross talk.
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