Authors: Christophe Caloz
Source: FERMAT, Volume 11, Communications 9, Sep_Oct, 2015
Abstract: Everything in our universe occurs in space, time, and spacetime where space and time are interdependent. These concepts are therefore fundamental across all areas of human activities, including history, economy, philosophy, arts and sciences.
The author believes systematic endeavours in manipulating waves in space, time and spacetime will bring about considerable opportunities towards the development of tomorrow’s electromagnetic science and technology.
Manipulation waves in space essentially consists in engineering their spatial frequency (k) spectrum, which may be performed using conventional electromagnetic structures, such as apertures, antennas, lenses, polarizers, photonic crystals, Talbot imagers, optical masks, etc. However, the frontiers of spatial dispersion engineering may be pushed far beyond the current state of the art, particularly using the novel concept of metasurfaces. The slides present several innovations in this area, including magnetless non-reciprocal gyrotropy, generalized refraction,multiple wave transformation, multi-refringence, and orbital angular momentum multiplexing.
In time, manipulating waves essentially consists in engineering their temporal frequency () spectrum, as partly done in ultrafast optics where oscillations are too fast to be handled by digital signal processors, and where real-time chirping and nonlinear materials and device shave therefore to be used instead. Such concepts have been little explored in electromagnetics, and may represent a solution to the exploding demand for faster and more reliable radio if sufficient progress is made. The author developed in his group metamaterial-inspired structure scalled phasers, which provide specifiable group delay versus frequency responses to perform unprecedented temporal dispersion engineering.The slides present the related Radio Analog Signal Processing (R-ASP) concept and technology, and demonstrate a number of related applications, such as spectrum sniffing, real-time Fourier analysis, and dispersion code multiple access.
Aforementioned concepts typically concern monochromatic spatial dispersion engineering and mono-directional temporal dispersion engineering. Combining the two aspects in simultaneous space and time dispersion engineering, as nature does it in rainbows and humans in holograms, will open up further horizons in electromagnetics processing. The slides also address this area, first introducing the fundamental concept of temporal to spatial frequency mapping, and next describing a few recent applications, including real-time spectrogram analysis and two-dimensional mapping for the processing of ultrafast waves.
Finally, novel concepts in electromagnetic space-time discontinuities, where space and time are interdependent as in the theories of special and general relativity, will be introduced and discussed as a potential platform for future developments in electrodynamics.
View PDFMetamaterial-based Electromagnetic Space, Time & Space-Time Dispersion Engineering