A stuffed ghost rests on a trader’s screen above the floor of the New York Stock Exchange (NYSE) after Snap Inc. listed their IPO in New York, U.S., March 2, 2017.ReutersSnap Inc. investors need to do a reality check instead of getting carried away by the euphoria generated after the shares of the company listed at a huge premium to the IPO price. Snap shares gained 44 percent on listing and closed at $24.5 on Thursday on the NYSE as against the issue price of $17. Snap, which owns photo-sharing mobile app Snapchat, had a bull run on Friday, gaining 10.66 percent to end at $27.09, translating into a cumulative gain of 59.35 percent and valuing Snap Inc. at almost $32 billion.On its first day itself, the company’s valuation soared to $28.4 billion at $24.5 per share. The company sold 200 million shares to investors to raise $3.4 billion in its successful initial public offering (IPO).But is the valuation justified and should investors be cautious? The answer seems yes. A Bloombergquint columnist warned that long-term investors are in for “disappointment,” citing profitability factor at the time of going public.Leonid Bershidsky said that out of 20 tech companies that went public in the US in the last decade, nine are trading below the issue (IPO) price. Out of these, six firms, such as Renren, Groupon and Lending Club, incurred losses in the year before they went public. “The first trading day is soon forgotten and investors start looking at financial reports, one at a time,” he wrote. It is pertinent here that Snap Inc. incurred a loss of $500 million on total revenues of $400 million in the calendar year 2016. It had about 100 million users. The losses widened from $382 million 2015, though revenues spiked from $59 million.Twitter, which went public in 2013 by selling 70 million shares at $26 per share, listed at $45 on November 7, 2013, a gain of 73 percent. However, the share has been on a freefall since then and closed at $15.75 on Friday. Traders gather on the floor for the IPO of Snap Inc. at the New York Stock Exchange (NYSE) in New York, U.S., March 2, 2017.Reuters
SEM micrographs of Archimedean spirals with (a) one, (b) two, and (c) three arms. Credit: Stellinga et al. ©2018 American Chemical Society The main way to do this is by controlling the number of “arms” the Archimedean spiral has. The number of arms is equal to the light beam’s topological charge, which is the number of twists the light beam makes in one wavelength. So the larger the number of arms, the tighter the helix of the light beam. Here, the researchers demonstrated Archimedean spiral gratings with between zero (no twist) and three arms. This new method for generating vortex lasers has advantages over previous methods in that the beams can be generated in a single step and by a single optical element (the grating). With these advantages, the researchers expect that the results will pave the way toward implementing vortex lasers in a variety of applications.”My main interest is in organic semiconductors, which can be simply patterned to make devices like this,” said Samuel, whose group provided the organic semiconductor gain material and conducted the measurements. “A long-term aim is to make such lasers electrically, rather than optically, driven. A nearer term aim is to use such lasers for sensing explosive vapor.”Krauss, whose group designed the nanostructures used in the study, is particularly interested in displays and microscopy applications.”In displays, you could use the different vortex orders to multiplex information—for example, to project multiple images at once,” he said. “Vortex beams are of interest in microscopy, so one can imagine an array of such beams for massively parallel microscopy.” Researchers have developed a new type of organic vortex laser, which is a laser that emits a helical beam of light. In the future, miniature arrays of these vortex lasers, each with a slightly different spiral shape, may be used in applications such as 3D TV displays, microscopy, and as information carriers for visible light communications. Explore further Illustration of an array of organic vortex lasers, each with a different spiral and therefore a different topological charge. Credit: Stellinga et al. ©2018 American Chemical Society The researchers, led by Ifor D. W. Samuel at the University of St. Andrews and Thomas F. Krauss at the University of York, both in the UK, have published a paper on the organic vortex lasers in a recent issue of ACS Nano.”Laser arrays have been demonstrated before, but not with such control over the beamshape,” Krauss told Phys.org. “Our approach allows us to make vortex beams of controlled topological charge. We can make Airy beams or Bessel beams. Similarly, metasurfaces that generate such bespoke beams have been demonstrated before, but they have been passive elements, not active lasers.” Previously, vortex laser beams have been generated by taking a laser and using separate optical components to shape the beam, resulting in large beams. The new vortex lasers demonstrated here have a nanostructured gain medium that generates the vortex beam directly. This means that it can be scaled down into miniature beams, which can then be arranged into an array. The miniaturized version is expected to be much more useful for practical applications.In order to generate helical light beams, the researchers designed an optical grating consisting of an Archimedean spiral. When light passes through the grating, it emerges as a helical beam. By controlling the dimensions of the spiral grating, it’s possible to control the properties of the light beam. Journal information: ACS Nano More information: Daan Stellinga et al. “An organic vortex laser.” ACS Nano. DOI: 10.1021/acsnano.7b07703 Laser beams with a ‘twist’ © 2018 Phys.org Citation: Organic vortex lasers could be used in future 3-D displays (2018, February 8) retrieved 18 August 2019 from https://phys.org/news/2018-02-vortex-lasers-future-d.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.