Just as there as waveguides for microwaves in the WiFi band could waveguides be scaled to work in the visible light band?
Waves radiate from an ideal source isotropically (in all directions). The function of a waveguide is to guide waves in a single direction - typically using the mechanism of total internal reflection.
A waveguide antenna transfers energy between electric power in a conductive medium (such as a metal wire) and electromagnetic waves in a non-conductive medium (such as air).
The width of a waveguide is typically in the same order of magnitude as the wavelength.
So wavelength of 2.4 GHz WiFi microwaves is about 12.5 cm.
For visible light in the 430–790 THz band the wavelength is about 380 to 700 nm. The scale of visible light is 180000-330000x smaller than of WiFi.
A waveguide antenna would thus need to be manufactured via nanotechnology.
It consists of a small dipole and a cylinder waveguide. The size of both is tuned to the frequency band is should operate on.
Currently nanotechnology is probably best explored for carbon which is a semi-conductor. However, typical waveguides are made of full conducting metals.
Since a single waveguide on this scale would be very small it can transfer only a little energy. Thus a large array of small elements would be probably needed in practice.
- emit light based on electric power
- lighting
- display
- absorb light and induce electric power
- sensor
- power source
- could this work?
- what should be the shape?
- in case of an array, how to synchronize all the elements?
- what materials would need to be used?
- how to manufacture the device?
- how to generate electric power at the scale of hundereds of THz?
- how to convert the electricity back to lower frequencies?
I came across this idea sometime back around in 2005 when playing with WiFi networks. Since then it seems there was some research in this area.