Photonic metamaterial
[10] Photonic crystals differ from PM in that the size and periodicity of their scattering elements are larger, on the order of the wavelength.
[11] While researching whether or not matter interacts with the magnetic component of light, Victor Veselago (1967) envisioned the possibility of refraction with a negative sign, according to Maxwell's equations.
And in 2002, Guerra et al.[18] published their demonstrated use of subwavelength nano-optics (photonic metamaterials) for optical data storage at densities well above the diffraction limit.
This was combined with a symmetrically positioned electric conducting post, which created the first negative index metamaterial, operating in the microwave band.
Photonic crystals, like many other known systems, can exhibit unusual propagation behavior such as reversal of phase and group velocities.
Negative magnetic permeability was originally achieved in a left-handed medium at microwave frequencies by using arrays of split-ring resonators.
Hence, the magnetic component of a radiated electromagnetic field has virtually no effect on natural occurring materials at optical frequencies.
[33] In metamaterials the cell acts as a meta-atom, a larger scale magnetic dipole, analogous to the picometer-sized atom.
Microwave metamaterials can be fabricated from circuit board materials, while lithography techniques must be employed to produce PMs.
[13][34][35][36] In 2014 a polarization-insensitive metamaterial prototype was demonstrated to absorb energy over a broad band (a super-octave) of infrared wavelengths.
The material displayed greater than 98% measured average absorptivity that it maintained over a wide ±45° field-of-view for mid-infrared wavelengths between 1.77 and 4.81 μm.
The polyimide cap protects the screen and helps reduce any impedance mismatch that might occur when the wave crosses from the air into the device.
)[39] The material combined two optical nanostructures: a multi-layered block of alternating silver and glass sheets and metal grates.
The silver-glass structure is a "hyperbolic" metamaterial, which treats light differently depending on which direction the waves are traveling.
[39] Adding chromium grates with sub-wavelength spacings bent incoming red or green light waves enough that they could enter and propagate inside the block.
On the opposite side of the block, another set of grates allowed light to exit, angled away from its original direction.
[39] Such structures hold potential for applications in optical communication—for instance, they could be integrated into photonic computer chips that split or combine signals carried by light waves.
Other potential applications include biosensing using nanoscale particles to deflect light to angles steep enough to travel through the hyperbolic material and out the other side.
[39] By employing a combination of plasmonic and non-plasmonic nanoparticles, lumped circuit element nanocircuits at infrared and optical frequencies appear to be possible.
[40] Subwavelength lumped circuit elements proved workable in the microwave and radio frequency (RF) domain.
Conventional silicon dielectrics have the real permittivity component εreal > 0 at optical frequencies, causing the nanoparticle to act as a capacitive impedance, a nanocapacitor.
Conversely, if the material is a noble metal such as gold or silver, with εreal < 0, then it takes on inductive characteristics, becoming a nanoinductor.
[5] A stacking technique for SRRs was published in 2007 that uses dielectric spacers to apply a planarization procedure to flatten the SRR layer.
[5][43][44] In 2014 researchers announced a 400 nanometer thick frequency-doubling non-linear mirror that can be tuned to work at near-infrared to mid-infrared to terahertz frequencies.
