Researchers at Osaka University accurately and arbitrarily control the flying speeds of light bullets, offering new possibilities for optical and physical applications.
Although it sounds strange to science fiction, controlling the speed of light has in fact been a long-standing challenge for physicists. In a study recently published in Physics of communications, researchers from Osaka University generated light bullets at very controllable speeds.
According to Albert Einstein’s principle of relativity, the speed of light is constant and cannot be exceeded; however, it is possible to control the velocity of the optical pulse array.
Currently, the spatio-temporal fusion of optical pulses provides an opportunity to control the speed of the group of three-dimensional non-diffraction optical wave packets, known as “light bulbs”, in free space.
In their previous study (Scientific Reports), this group found that by deforming the front of the optical pulse pulse and keeping the front of the phase unchanged, the velocity and acceleration of Bessel-Gaussian light bulbs (without diffraction and scattering) can be controlled.
“However, the problem is that only a defined form of motion, for example, superluminal or subluminal for velocity and acceleration or deceleration for acceleration, can be achieved in a single propagation path,” explains relevant author Zhaoyang Li.
In this newly improved method, using a combination of a deformable mirror and a spatial light modulator, the front of the optical pulse can be arbitrarily deformed, resulting in arbitrary light bulbs (and accelerations) variable during a single path propagation; e.g., subluminal followed by superluminal and / or acceleration followed by deceleration.
“This non-diffraction light bullet with almost programmable flight speeds can bring new opportunities in a wide range of applications, such as free space communication, bio-imaging, optical detection and processing, acceleration and particle manipulation, radiation generation, among others, ”says Zhaoyang Li.
Reference: “Group programmable optical wave packet speed” by Zhaoyang Li and Junji Kawanaka, November 13, 2020, Communication Physics.
DOI: 10.1038 / s42005-020-00481-4