Order from chaos

EurekAlert  November 13, 2020 Current technology in LiDARS bounces the laser beams off moving mirrors, a mechanical method that results in slower scanning speeds and inaccuracies. Researchers in Japan have developed a new beam scanning device utilizing ‘photonic crystals’ whose lattice points can be arranged as nanoscale antennae. They found that by adjusting both position and size resulted in a seemingly random photonic crystal, producing an accurate beam without power loss. They called this a ‘dually modulated photonic crystal’. They showed that the scanner can generate beams in one hundred different directions: a resolution of 10×10. With further refinements, the […]

60-year-old limit to lasers overturned by quantum researchers

Phys.org  October 27, 2020 Researchers in 1958 showed theoretically that the coherence of a beam cannot be greater than the square of the number of photons stored in the laser based on the assumptions they made about how energy is added to the laser and how it is released to form the beam. Now according to researchers in Australia the assumptions made sense at the time, and still apply to most lasers today, but they are not required by quantum mechanics. They have shown that the true limit imposed by quantum mechanics is that the coherence cannot be greater than […]

Physicists make electrical nanolasers even smaller

EurekAlert  September 16, 2020 An international team of researchers (Russia, UK) has developed a new approach to create electrically driven nanolasers for integrated circuits. In their approach electrical pumping is based on a double heterostructure with a tunneling Schottky contact. Plasmon-polaritons (SPPs) replace photons. The pumping happens across the interface between the plasmonic metal and semiconductor, along which surface SPPs propagate. The pumping approach makes it possible to bring the electrically driven laser to the nanoscale, while retaining its ability to operate at room temperature and the radiation is effectively directed to a photonic or plasmonic waveguide, making the nanolaser […]

New metasurface laser produces world’s first super-chiral light

EurekAlert  April 27, 2020 An international team of researchers (South Africa, USA – Harvard University, Singapore) has developed a new laser to produce any desired chiral state of light, with full control over both angular momentum (AM) components of light, the spin (polarisation) and orbital angular momentum (OAM) of light. They designed a new nanometer-sized metasurface made up of many tiny rods of nanomaterial within the laser, which alters the light as it passes through. The light passes through the metasurface many times, receiving a new twist every time it does so resulting in the generation of new forms of […]

All Militaries Are Developing Combat Lasers So They Will Give Short Military Advantages

Next Big Future  June 3, 2019 Fourth generation fighters (F-16, F-18) and fifth-generation fighters (F-35, F-22) can be seen by shorter range radar. They only have a 20-30 percent chance of evading new short-range missiles. New 50 kilowatt and 150-kilowatt combat lasers that will be added to fighters in the next few years will provide extra defenses to hinder missiles. Combat Lasers could increase the survivability of both stealth and non-stealth fighters and force more missiles to be used to overcome defenses. The US Air Force LANCE laser program will use fiber-optic cables to merge beams to reach tens of […]

Physicists propose perfect material for lasers

Eurekalert  May 8, 2019 In Weyl semimetals charge carriers behave the way electrons and positrons do in particle accelerators. Researchers in Russia have shown that reactions forbidden for elementary particles can also be forbidden in the crystalline materials known as Weyl semimetals. Specifically, this applies to the forbidden reaction of mutual particle-antiparticle annihilation without light emission. This property suggests that a Weyl semimetal could be the perfect gain medium for lasers. The team gauged the lifetime of an electron-hole pair in a Weyl semimetal to be about 10 nanoseconds which is much longer than in conventional materials used in laser […]

Lasers make magnets behave like fluids

Science Daily  April 18, 2019 When a magnet is hit with a short enough laser pulse the spins within a magnet will no longer point just up or down, but in all different directions canceling out the metal’s magnetic properties. Using mathematical modeling, numerical simulations and experiments an international team of researchers (USA – University of Colorado, NIST, SLAC, Temple University, UK, Sweden, U, Italy, Germany, China, Japan, Belgium) has shown that the spins behaved like a superfluid 3 picoseconds after a laser pulse hits and then form small clusters with the same orientation like “droplets” in which the spins […]

A “Laser for Sound” from a Levitated Nanoparticle

Optics and Photonics News  April 19, 2019 A team of researchers in the US (University of Rochester, Los Alamos National Laboratory) used feedback loops to optomechanically manipulate the oscillations of a silica nanosphere levitated in an optical trap. In so doing, they were able to create laser-like amplification and coherence of phonons—quanta of vibrational or acoustic energy, analogous to photons in the optical domain. The team believes that the setup opens a general technique for creating frequency-tunable sound lasers in a system-size range that hasn’t previously been explored. The result, according to the researchers, could provide a useful tool both […]

New shapes of laser beam ‘sneak’ through opaque media

Phys.org  March 4, 2019 A team of researchers in the US (Yale University, Missouri University of Science & Technology) used a spatial light modulator (SLM) and a CCD camera to analyze an opaque material that is made of a layer of white paint, biological tissue, fog, paper, and milk. The SLM tailors the laser beam incident on the front surface of the material, and the CCD camera records the intensity profiles behind it. The resulting beam was more concentrated, with more light per volume inside and behind the opaque material. The method works for any opaque medium that does not […]

Lasers can send a whispered audio message directly to one person’s ear

MIT Technology Review  January 28, 2019 To send the messages, researchers from MIT Lincoln Laboratory relied upon the photoacoustic effect in which water vapor in the air absorbs light and forms sound waves. The researchers used a laser beam to transmit a sound at 60 decibels (roughly the volume of background music or conversation in a restaurant) to a target person who was standing 2.5 meters away. A second technique modulated the power of the laser beam to encode a message, which produced a quieter but clearer result. The team used it to beam music, recorded speech, and various tones, […]