Lifeboat Foundation

Large-capacity wireless data transmission systems are demanded along with the development of multimedia services, video-based interactions, and cloud computing in the era of big data. Compared with radio-frequency communication systems, free-space optical (FSO) signal transmission technology has the merits of high data rate, great flexibility, less power consumption, high security, and large license-free bandwidths [1– 3], which has been widely applied in terrestrial transmission [4], last mile solutions [5], ground-to-satellite optical communication [6], disaster recovery [7], and so on. To date, up to 10 Gbit/s FSO communication system has been realized for transmission distance over 1,000 km of star-ground or inter-star communications [8], and 208 Gbit/s terrestrial communication is also reported at 55 m transmission distance [9]. Wavelength-division multiplexing (WDM) technology is commonly employed to improve data transmission capacity in fiber communication systems, which would be more effective in FSO communication systems benefitting from very weak non-linear cross talk between different frequency channels in free space. Based on a simulation platform, a WDM FSO communication system could boost the signal transmission capacity to 1.28 Tbit/s by modulating 32 optical channels with dual-polarization 16 quadrature amplitude modulation signals [10]. To date, beyond 10 Tbit/s FSO communication systems have been experimentally demonstrated recently using WDM technology [11,12]. However, a WDM communication system becomes power-hungry and bulky with the increase of transmission channels while traditional distributed feedback lasers are used as optical carriers. In addition, more rigorous requirement is imposed on the frequency tolerance of carrier lasers to avoid channel overlap with the decrease of channel frequency interval.

The invention of microresonator-based optical frequency combs provides novel integrated optical laser sources with the natural characteristic of equi-spaced frequency intervals which can overcome the challenge of massive parallel carrier generation [13 – 19]. In particular, the spontaneously organized solitons in continuous-wave (CW)-driven microresonators provide a route to low-noise ultra-short pulses with a repetition rate from 10 GHz to beyond terahertz. Soliton microcombs (SMCs) are typical stable laser sources where the double balances of non-linearity and dispersion as well as dissipation and gain are reached in microcavities. Meanwhile, the linewidth of the comb lines is similar with the pump laser, which enables low power consumption and costs multiwavelength narrow-linewidth carriers for a wide range of applications. Through designing the scale of microresonators, the repetition rate of SMCs could be compatible with dense wavelength-division multiplexing (DWDM) communication standard. To date, several experiments have demonstrated the potential capacity for ultra-high-speed fiber communication systems using SMCs as multiwavelength laser sources [20 – 30]. For instance, a coherent fiber communication system has improved the transmission capacity up to 55 Tbit/s using single bright SMCs as optical carriers and a local oscillator [20]. And dark solitons and soliton crystals are also employed as multiwavelength laser sources for WDM communication systems [27 – 30]. However, few studies have carried out massive parallel FSO communication systems using the integrated SMCs as laser sources.

In this paper, we experimentally demonstrate a massive parallel FSO communication system using an SMC as a multiple optical carrier generator. 102 comb lines are modulated by 10 Gbit/s differential phase shift keying (DPSK) signals to boost the FSO transmission rate up to beyond 1 Tbit/s. The transmitter and receiver terminals are installed in two buildings at a distance of ∼1 km, respectively. Using a CW laser as reference, the influence of optical signal-to-noise ratios (OSNRs) on the bit error rate (BER) performance is experimentally analyzed. Our results show an effective solution for large-capacity spatial signal transmission using an integrated SMC source which has potential applications in future satellite-to-ground communication systems.

Greer and Ivanov agree that existing, albeit limited, data on tetrataenite’s magnetic properties suggest that it may not match high-performance neodymium-based magnets. But the researchers maintain that optimization of the tetrataenite casting process could improve its magnetic properties and thus make it a worthwhile option. “It is good to have a wider range of permanent magnet materials, because that allows better balancing of such factors as magnetic performance and environmental impact,” Greer says. “A one-for-one swap with rare-earth magnets is not necessarily the goal.”

For now, the team has demonstrated how to make a piece of tetrataenite, but they say that future work will focus on how to consolidate many pieces into a bulk magnet. “The analogy here would be that we have shown we can make a brick—a piece of tetrataenite—but not yet a house—a magnet,” Greer says.

Beyond materials science, the researchers hint that this work may even impact astrophysics research as scientists reconsider how long it takes for tetrataenite to develop in a meteorite and how fast the cooling rate is in that space environment.

An international team of astronomers have turned a new technique onto a group of galaxies and the faint light between them—known as ‘intra-group light’—to characterize the stars that dwell there.

Lead author of the study published in MNRAS, Dr. Cristina Martínez-Lombilla from the School of Physics at UNSW Science, said We know almost nothing about intra-group light.

The brightest parts of the intra-group light are ~50 times fainter than the darkest night sky on Earth. It is extremely hard to detect, even with the largest telescopes on Earth—or in space.

The James Webb Space Telescope has captured a detailed molecular and chemical portrait of a faraway planet’s skies, scoring another first for the exoplanet science community.

WASP-39b, otherwise known as Bocaprins, can be found orbiting a star some 700 light-years away. It is an exoplanet — a planet outside our solar system — as massive as Saturn but much closer to its host star, making for an estimated temperature of 1,600 degrees Fahrenheit (871 degrees Celsius) emitting from its gases, according to NASA. This “hot Saturn” was one of the first exoplanets that the Webb telescope examined when it first began its regular science operations.

The new readings provide a full breakdown of Bocaprins’ atmosphere, including atoms, molecules, cloud formations (which appear to be broken up, rather than a single, uniform blanket as scientists previously expected) and even signs of photochemistry caused by its host star.

Human-robot hybrids are advancing quickly, but the applications aren’t just for complete synthetic humans. There’s a lot we can learn about ourselves in the process.

Hosted by: Hank Green.

Continue reading “Why Scientists are Giving Robots Human Muscles” »

WASP-39b could be key to finding much calmer, more habitable worlds.

The James Webb Space Telescope (JWST) has just scored another first: a detailed molecular and chemical portrait of a distant world’s skies.

The telescope’s array of highly sensitive instruments was trained on the atmosphere of a “hot Saturn”—a planet about as massive as Saturn orbiting a star some 700 light-years away—known as WASP-39 b. While JWST and other space telescopes, including Hubble and Spitzer, have previously revealed isolated ingredients of this broiling planet’s atmosphere, the new readings provide a full menu of atoms, molecules, and even signs of active chemistry and clouds.

Continue reading “James Webb Space Telescope reveals an exoplanet atmosphere as never seen before” »

“We are going to be able to see the big picture of exoplanet atmospheres.”

NASA’s James Webb Space Telescope has provided a detailed molecular and chemical profile of a distant exoplanet’s skies in a world first, a blog post from the space agency reveals.

However, the new observations from James Webb reveal the makeup of the exoplanet’s atmosphere like never before and reveal further details of active chemistry and clouds.

Continue reading “James Webb uncovers the mysteries of an alien world’s atmosphere 700 light-years away” »

In this video we discuss the different types of civilizations mention in the Culture series by Iain M. Banks. This video wont have any major spoilers for the series.

Art: https://docs.google.com/document/d/16JYYq4_SqGtPirGfSc6otg_a…sp=sharing.

Continue reading “The Species That Eats The Universe | Culture” »