Anomalous refraction of optical spacetime wave packets


Ayman Abouraddy and his team at UCF’s College of Optics and Photonics have developed a new type of laser beam that defies long-held principles about how light travels through different mediums. Light refracts as it travels from one medium to the next which is a fundamental principle in regards to light traveling through the atmosphere or interacting with photonic devices. However, by controlling the spatiotemporal aspects of a beam it is possible to work around the traditional rules of refraction of an optical field. Endowing a beam with precise spatiotemporal spectral correlations allows for refractory phenomena previously only theorized but now demonstrated including group-velocity invariance with respect to the refractive index, group-delay cancellation, anomalous group-velocity increase in higher-index materials, and tunable group velocity by varying the angle of incidence. These spacetime (ST) wave packets defy the normal expectations given from Fermat’s principle allowing for new opportunities for controlling the flow of light and other wave structures. [1]

From a communication standpoint, these ST wave packets have huge implications. Normally, when light passes from a material with a lower refractive index to a material with a higher refractive index, the beam loses group velocity which can increase the delay in optical communication. In contrast, ST wave packets keep their group velocities regardless of the materials they pass through. If these packets were to be introduced into communication technologies then delay or signal loss due to atmospheric turbulence could be controlled or reduced significantly. This would create a massive opening for FSO or other optical technologies in the future. [2]

Related Links

Paper: Complete modal decomposition for optical waveguides

UCF: Ayman Abouraddy