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Semiconductor Lasers and particularly Vertical-Cavity Surface-Emitting Lasers (VCSELs) are important laser sources used for many purposes. However, the applications of these lasers are mainly restricted by their strongly multimode operation given by the lack of an intrinsic transverse mode selection mechanism [1]. The introduction of an axial PT-symmetric potential within this kind of lasers is expected...
Since the advent of transformation optics a decade ago [1], the ability to achieve optical cloaking has become a matter of practical realization. However, so far extreme material requirements and large device areas have significantly posed an obstacle to realize compact cloaking schemes that are fully functional. Here, by taking a different approach and by following our recently developed general...
We propose a new type of add-drop microring resonator made of gain and loss materials. Microring resonators are compact, narrow band, and optical channel dropping filters. In such linear systems, light transmission to side-coupled signal waveguides is always symmetric. However, we prove that properly arranging a gain and loss modulation in the microring resonator provides a new functionality: asymmetric...
Optical Parity-Time (PT-) symmetric systems support unusual properties. When the symmetric coupling between internal modes is broken the system becomes strongly unidirectional resulting in novel effects such as asymmetric reflections, invisibility or asymmetric mode coupling. Here, we propose a new class of nanophotonic PT-axisymmetric systems which lead to an extreme field enhancement and high localization...
We numerically investigate the design of a wavelength de-multiplexer based on a tapered photonic crystal waveguide. The tapered waveguide is generated by reducing the width of the channel which, in turn, provides a gradual change in the effective index for the guided modes. Depending on the wavelength, the grading effect enables the propagating beam to be trapped at different spatial positions along...
One of the most inconvenient of Broad Area Semiconductor Lasers is the large amount of spatial modes involved in the output beam and the possible temporal unstabilization due to their interaction. This introduces strong difficulties in the output beam focalization in order to be coupled to fibers or other devices. One possibility to increase the output beam quality of these devices is a spatial modulation...
The propagation of light through 3D ordered photonic nanostructures is strongly affected by real aspects of actual crystals, especially at the spectral range where the wavelength of light is on the order of the lattice parameter. We perform a theoretical study on anomalous light propagation in finite thin artificial opal slabs made of a reduced number of layers. The vector KKR method we use accounts...
In broad band semiconductors, spatial modulations can be introduced by different mechanisms. In any case and due to the particular relation of electric field and population inversion of the material, both gain and index spatial modulations are induced. In the case of semiconductor materials, the amplitudes of these two modulations are connected by the so called alfa-factor of the material. We analyse...
We predict and demonstrate that the periodical modulation of the gain/loss profile on the wavelength scale in at least two dimensions of space can lead to interesting beam propagation effects, similar to self-collimation or subdiffractive propagation, but also to spatial beam filtering.
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