Phys.org January 7, 2020 Most of the previous studies demonstrated spatial focusing to the speckle grain size, and manipulation of the temporal properties of the achieved focus. Researchers in Australia demonstrate an approach to control the total temporal impulse response, not only at a single speckle grain but overall spatial degrees of freedom (spatial and polarization modes) at any arbitrary delay time through a multimode fiber. Global enhancement or suppression of the total light intensity exiting a multimode fibre is shown for arbitrary delays and polarization states. This work could benefit to applications that require pulse delivery in disordered media, […]
Tag Archives: Laser
Quantum dot lasers move a step closer with electric-pumping development
Phys.org November 29, 2019 Colloidal quantum dots (CQDs) are highly promising materials for light amplification. But band-edge state degeneracy demands multiple excitons to achieve population inversion increasing the lasing threshold and limits the gain lifetime. Researchers in Singapore have demonstrated that the amplified spontaneous emission (ASE) threshold is controllable in a device where CQD film is exposed to an external electric field. Specifically, singly charged CQDs lower the threshold due to the preexisting electron in the conduction band, while strongly enhanced Auger recombination in doubly charged CQDs stymies the ASE. According to the researchers the next big challenge in laser […]
Laser combo opens up futuristic terahertz technology
Physics World November 25, 2019 The terahertz region of the electromagnetic spectrum has been the least utilized owing to inadequacies of available sources. A team of researchers in the US (Harvard University, MIT, Duke University) has created a compact, widely frequency-tunable, extremely bright source of terahertz radiation: a gas-phase molecular laser based on rotational population inversions optically pumped by a quantum cascade laser. By identifying the essential parameters that determine the suitability of a molecule for a terahertz laser, almost any rotational transition of almost any molecular gas can be made to lase. Nitrous oxide is used to illustrate the […]
US Navy and Missile Defense Agency Megawatt Lasers by 2023-2024
Next Big Future August 8, 2019 In 2018, the US Navy and Missile Defense Agency had targeted demonstrating megawatt lasers by 2023-2024. The US Army recently had an announcement of a contract for 250-300 kilowatt lasers on a large truck by 2024. This means that four container-sized laser power systems could be combined on a Navy ship or at a Missile Defense base for a megawatt laser. A large US Army truck is the same size as a shipping container. A mobile 250-kilowatt laser has all the power, fuel and electronics for module that could be used for a megawatt […]
Scientists develop polariton nano-laser operating at room temperature
Phys.org May 20, 2019 Progress toward room temperature polariton nanolasers has been limited by the thermal instability of excitons and the inherently low-quality factors of nanocavities. An international team of researchers (South Korea, University of Pennsylvania) has produced a quantum well on the sidewall of a nanostructure semiconductor and succeeded in maintaining thermally stable excitons even at room temperature. The quantum well structure contributed to the formation of more efficient and stable exciton-polariton states than before by strengthening the coupling of exciton and light inside the nanostructure semiconductor. Their polariton nano-lasers are stable at room temperature and operate at only […]
Researchers transmit data via a semiconductor laser, opening the door to ultra-high-speed Wi-Fi
Phys.org April 25, 2019 Previously the team of researchers in the US (Harvard University, Texas A&M, MIT Lincoln Laboratory) discovered that an infrared frequency comb in a quantum cascade laser could be used to generate terahertz frequencies, quantum cascade laser frequency combs could also act as integrated transmitters or receivers to efficiently encode information. Now they created a dipole antenna on the electrode of the device, modulated the frequency comb to encode information on the microwave radiation created by the beating light of the comb. Using the antenna, the microwaves containing the encoded information are radiated out from the device. […]
Liquid crystals could help deflect laser pointer attacks on aircraft
Optics.org April 2, 2019 Researchers at Lewis University, Illinois, focused on the polarization and absorbance properties of liquid crystal materials to block incoming laser light. To decrease the intensity of incoming laser light, the liquid crystal N-(4-Methoxybenzylidene)-4-butylaniline was deposited between two pieces of conductive indium tin oxide-coated glass. The test cell can decrease up to 80 percent of incoming laser light by transitioning from its transparent, liquid phase to its opaque, pseudo-crystalline phase, with the cell being able to return to its transparent phase in less than three seconds. The phase change is controlled by an electric current applied to […]
Concept of the laser can be reversed
Science Daily March 4, 2019 An international team of researchers (Austria, France) used microwave technology to build a random anti-laser and demonstrate its ability to absorb suitably engineered incoming radiation fields with near-perfect efficiency. They found that there is a complex scattering process in which the incident wave splits into many partial waves, which then overlap and interfere with each other in such a way that none of the partial waves can get out at the end. Potential uses of anti-laser technology could be to adjust a signal exactly the right way so that it is perfectly absorbed by the […]
Bursting the clouds for better communication
Phys.org October 18, 2018 Researchers in Switzerland have developed a laser that heats the air over 1,500 degrees Celsius and produces a shock wave to expel the suspended water droplets sideways. This creates a hole a few centimetres wide over the entire thickness of the cloud. The laser beam should be kept on the cloud and the laser that contains the information should be sent at the same time. It then slips into the hole through the cloud and allows the data to be transferred. This “laser cleaner” is currently being tested on artificial clouds that are 50 cm thick […]
Physicists Tied Laser Beams into Knots
Live Science August 3, 2018 An international team of researchers (Canada, UK, USA – University of Rochester, University of Birmingham) created the knots by tuning the polarization of two beams of light. The knots formed around “polarization singularities” where the beams intersected and a number of other wavelengths of light looped around them. At those points, light bent in the way the researchers wanted. The knots were visible enough in images of the light wave data for them to identify the figure eights and toruses. They also confirmed their findings using formal knot theory mathematics. They hope this technology will […]