Mar 8, 2021
Twistoptics: A New, Efficient Way to Control Optical Nonlinearity
Posted by Saúl Morales Rodriguéz in categories: biotech/medical, chemistry, cybercrime/malcode, engineering, quantum physics, solar power
Columbia researchers engineer first technique to exploit the tunable symmetry of 2D materials for nonlinear optical applications, including laser, optical spectroscopy, imaging, and metrology systems, as well as next-generation optical quantum information processing and computing.
Nonlinear optics, a study of how light interacts with matter, is critical to many photonic applications, from the green laser pointers we’re all familiar with to intense broadband (white) light sources for quantum photonics that enable optical quantum computing, super-resolution imaging, optical sensing and ranging, and more. Through nonlinear optics, researchers are discovering new ways to use light, from getting a closer look at ultrafast processes in physics, biology, and chemistry to enhancing communication and navigation, solar energy harvesting, medical testing, and cybersecurity.
Columbia Engineering researchers report that they developed a new, efficient way to modulate and enhance an important type of nonlinear optical process: optical second harmonic generation — where two input photons are combined in the material to produce one photon with twice the energy — from hexagonal boron nitride through micromechanical rotation and multilayer stacking. The study was published online on March 32021, by Science Advances.
The plasma compression fusion device (PCFD) generates the energy gain by plasma compression-induced nuclear fusion. This concept has the capability of maximizing the product of plasma pressure and energy confinement time to maximize the energy gain, and thus give rise to fusion ignition conditions. The preferred embodiment of this original concept uses a hollow cross-duct configuration of circular cross section in which the concentrated magnetic energy flux from two pairs of opposing curved-headed counter-spinning conical structures (possibly made from an alloy of tungsten with high capacitance) whose outer surfaces are electrically charged compresses a gaseous mixture of fusion fuel into a plasma, heated to extreme temperatures and pressures. The generated high-intensity electromagnetic (EM) radiation heats the plasma and the produced magnetic fields confine it in between the counter-spinning conical structures, named the dynamic fusors (four of them-smoothly curved apex sections opposing each other in pairs). The dynamic fusors can be assemblies of electrified grids and toroidal magnetic coils, arranged within a conical structure whose outer surface is electrically charged. The cross-duct inner surface surrounding the plasma core region is also electrically charged and vibrated in an accelerated mode to minimize the flux of plasma particles (including neutrals) from impacting the PCFD surfaces and initiating a plasma quench. The fusion fuel (preferably deuterium gas) is introduced into the plasma core through the counterspinning conical structures, namely, injected through orifices in the dynamic fusor heads. There is envisioned another even more compact version of this concept, which uses accelerated vibration in a linear-duct configuration (using two counterspinning dynamic fusors only) and would best be suited for fusion power generation on aircraft, or main battle tanks. The concept uses controlled motion of electrically charged matter through accelerated vibration and/or accelerated spin subjected to smooth, yet rapid acceleration transients, to generate extremely high-energy/high-intensity EM radiation (fields of high-energy photons) which not only confines the plasma but also greatly compresses itso as to produce a high power density plasma burn, leading to ignition. The PCFD concept can produce power in the gigawatt to terawatt range (and higher) with input power in the kilowatt to megawatt range and can possibly lead to ignition (selfsustained) plasma burn. Several important practical engineering and operational issues with operating a device such as the PCFD are discussed.
