Science Daily January 30, 2019 A team of researchers (South Africa, UK) has observed a variety of fractal shapes in transverse intensity cross sections through the lowest-loss eigenmodes of unstable canonical laser resonators, thereby demonstrating the controlled generation of fractal light inside a laser cavity. They advance the existing theory of fractal laser modes, first by predicting three-dimensional self-similar fractal structure around the center of the magnified self-conjugate plane and second by showing, quantitatively, that intensity cross sections are most self-similar in the magnified self-conjugate plane. The work offers a significant advance in the understanding of a fundamental symmetry of […]
Tag Archives: Lasers
New laser technology can identify unknown white powders from safe distance
Phys.org October 8, 2018 An international team of researchers (UK, USA – industry) was able to identify 11 white powder samples using their infrared laser system. No samples or disturbance of the powders were required, and they could be identified from up to one metre away. They illuminated each sample with broadband coherent light in the 8–9-µm band. Similarities between different spectra were quantified using Pearson’s correlation coefficient, confirming that spectral features in the 8–9-µm wavelength region were sufficient to discriminate between all eleven powders evaluated in the study. The researchers believe that the identification system will prove most useful […]
Building miniature lasers using nanowire
Nanowerk August 29, 2018 An international team of researchers (Norway, Australia, Sweden) has developed single-mode and room-temperature lasing from 890 to 990 nm, utilizing a novel design of single nanowires with GaAsSb-based multiple axial superlattices as a gain medium under optical pumping. The control of lasing wavelength via compositional tuning with excellent room-temperature lasing performance is shown to result from the unique nanowire structure with efficient gain material, which delivers a low lasing threshold, a lasing quality factor as high as 1250, and a high characteristic temperature of ∼129 K. These results present a major advancement for the design and […]
A phonon laser operating at an exceptional point
Phys.org July 20, 2018 Exceptional points (EP) are singularities in the energy functions of a physical system at which two light modes coalesce to produce unusual effects. Understanding the mechanisms responsible for linewidth broadening will enable laser resources with new capabilities. An international of researchers led by the US used an optomechanical system with two coupled silica whispering-gallery-mode microresonators to exploit the interplay between gain and loss to tune a phonon laser to an EP. The team provided direct experimental evidence to show complete overlap of optical supermodes at EP, and that EP-enhanced optical noise can be transferred directly to […]
Multiple lasers could be replaced by a single microcomb
Science Daily June 12, 2018 An international team of researchers (Sweden USA – Purdue University) reports the first coherent-transmission experiments using 64-quadrature amplitude modulation encoded onto the frequency lines of a dark-pulse comb. The high conversion efficiency of the comb enables transmitted optical signal-to-noise ratios above 33 dB, while maintaining a laser pump power level compatible with state-of-the-art hybrid silicon lasers. The research helps to better understand the formation of dark pulses in microresonators and their potential use in optical communications. The research could lead to faster and more power-efficient optical communication links in the future… read more. Open Access TECHNICAL […]
New approach to generating ultrashort laser pulses
Nanowerk June 8, 2018 An international team of researchers (USA – MIT, The Ohio State University, Germany) used an optical parametric amplifier to produce pulses which cover different spectral ranges and whose amplitudes and phases can be fixed relative to one another. The amplifier has a very short time delay between the two pulses so that they combine into a wide-bandwidth pulse with no need for noise control. The pulse could be made even shorter than the period of the wave because constructive interference occurs at its center, while destructive interference ‘trims’ the pulse at its edges. When the pulses […]
New laser makes silicon ‘sing’
Eurekalert June 7, 2018 To amplify silicon laser with sound, a team of researchers in the US (Yale University, Northern Arizona University, UT Austin) used a nanoscale waveguide that is designed to tightly confine both light and sound waves and maximize their interaction. The waveguide has two distinct channels for light to propagate which allows shaping of the light-sound coupling in a way that permits remarkably robust and flexible laser designs. While the system is clearly an optical laser, it also generates very coherent hypersonic waves. According to the researchers these properties may lead to several potential applications ranging from […]
Photonics – Getting into the groove
Nanowerk June 8, 2018 An international team of researchers (Singapore, UK, Saudi Arabia, Germany) fabricated, analyzed and modeled a system consisting of the nano-grooved gold film topped with an atomically thin flake of tungsten selenide. The result was a remarkable 7,000-fold multiplication of second harmonic generation (SHG) by which two photons combine to produce a single photon with double the energy. They were able to combine the advantages of both materials to achieve a flexible, ultra-compact, and efficient device for SHG, with potential applications for optical frequency doubling in nanoscale devices… read more. TECHNICAL ARTICLE