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A detailed theoretical study of one-dimensional optical structures was performed by Vladimir P. Bykov, [12] who was the first to investigate the effect of a photonic band-gap on the spontaneous emission from atoms and molecules embedded within the photonic structure.
Alternatively, they can also be made with much lower effective index contrast. Alternatively, one can create a photonic bandgap photonic crystal fiber, in which the light is confined by a photonic bandgap created by the microstructured cladding—such a bandgap, properly designed, can confine light in a lower-index core and even a hollow (air ...
Based on their band structure, materials are characterised with a direct band gap or indirect band gap. In the free-electron model, k is the momentum of a free electron and assumes unique values within the Brillouin zone that outlines the periodicity of the crystal lattice.
In semiconductors, the band gap of a semiconductor can be of two basic types, a direct band gap or an indirect band gap. The minimal-energy state in the conduction band and the maximal-energy state in the valence band are each characterized by a certain crystal momentum (k-vector) in the Brillouin zone. If the k-vectors are different, the ...
In a semiconductor or band insulator, the Fermi level is surrounded by a band gap, referred to as the band gap (to distinguish it from the other band gaps in the band structure). The closest band above the band gap is called the conduction band , and the closest band beneath the band gap is called the valence band .
He has several research interests, but is mostly known for his work in the field of photonic crystals, where he made the first demonstration of two-dimensional photonic band-gap effects at optical wavelengths. [1]
At the Brillouin zone boundary the wave function is a standing wave composed of an incoming and a Bragg-reflected wave. This ultimately leads to the creation of a band gap. The nearly free electron approximation can be used to derive the basic properties of surface states for narrow gap semiconductors.
The materials employ a periodic, cellular structure. The subwavelength periodicity [2] distinguishes photonic metamaterials from photonic band gap or photonic crystal structures. The cells are on a scale that is magnitudes larger than the atom, yet much smaller than the radiated wavelength, [3] [4] are on the order of nanometers. [3] [4] [5]