نتایج جستجو برای: photonic crystals
تعداد نتایج: 76450 فیلتر نتایج به سال:
Transmittance of electromagnetic waves with normal incidence in one-dimensional plasma photonic crystals is studied numerically based on the invariant imbedding method. Wave transmittance as a function of wave frequency shows the appearance of forbidden band gaps, which are conspicuous in photonic crystals. We also demonstrate that the small modification of plasma photonic crystal leads to diff...
One of the principal goals in the design of photonic crystals is the engineering of band gaps and defect states. Here I describe the formation of topologically protected localized midgap states in systems with spatially distributed gain and loss. These states can be selectively amplified, which finds applications in the beam dynamics along a photonic lattice and in the lasing of quasi-one-dimen...
The main properties of photonic crystals stem from the existence of frequency ranges for which the propagation of electromagnetic waves in the medium is not permitted. These frequency ranges are commonly known as photonic band gaps and give the ability to modify the structure parameters, e.g., group velocity, coherence length, gain, and spontaneous emission. Photonic crystals’ properties are be...
Photonic crystals have been widely investigated since they have great potential to manipulate the flow of light in an ultra-compact-scale and enable numerous innovative applications. 2D slab photonic crystals for the telecommunication C band at around 1550 nm have multi-scale structures that are typically micron-scale waveguides and deep sub-micron-scale air hole arrays. Several steps of nanoli...
Flexible photonic crystals are attractive devices owing to their multifold tunable parameters additionally introduced by soft substrates or by nanostructured, nano-doped, or nano-embedded soft matters. This not only extends significantly the intrinsic functions of photonic crystals, but also facilitates easy integration of the photonic crystal device into various optoelectronic and sensing syst...
We present and use an algorithm based on convex conic optimization to design two-dimensional photonic crystals with large absolute band gaps. Among several illustrations we show that it is possible to design photonic crystals which exhibit multiple absolute band gaps for the combined transverse electric and magnetic modes. The optimized crystals show complicated patterns which are far different...
We studied coherent backscattering (CBS) of light from opal photonic crystals with incomplete band gaps. We observed a dramatic broadening of the CBS cone for incident angles close to the Bragg condition in the crystals. We modify the conventional CBS theory to incorporate Bragg attenuation resulting from the photonic band structure. By fitting the CBS data with the modified theory, we extract ...
Spatio-spectral transmission patterns induced on low coherence fields by disordered photonic crystals can be used to construct optical spectrometers. Experimental results suggest that 1-10 nm resolution multimodal spectrometers for diffuse source analysis may be constructed using a photonic crystal mounted on a focal plane array. The relative independence of spatial and spectral modal response ...
We demonstrate how micromachined photonic crystals can be used to negatively refract terahertz frequency light. The photonic crystals, which are constructed from conventional dielectric materials, manipulate the incident beam via interaction with their photonic bands. Consequently, we show that different components of a broadband beam incident on the structure may be positively or negatively re...
We present a formalism for optical pulse propagation in nonlinear photonic crystals of arbitrary dimensionality. Using a multiple-scale analysis, we derive the dynamical nonlinear Schrödinger equation obeyed by the envelope function modulating an underlying Bloch function. Effective coefficients appear in that equation characterizing the effects of Kerr nonlinearity, linear gain or loss, and ma...
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