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Recent studies on non-Hermitian optical systems having exceptional points (EPs) have revealed a host of unique characteristics associated with these singularities, including unidirectional invisibility, chiral mode switching and laser…
Weyl points, synthetic magnetic monopoles in the 3D momentum space, are the key features of topological Weyl semimetals. The observation of Weyl points in ultracold atomic gases usually relies on the realization of high-dimensional…
Electronic materials can sustain a variety of unusual, but symmetry protected touchings of valence and conduction bands, each of which is identified by a distinct topological invariant. Well-known examples include linearly dispersing…
Surface lattice resonance (SLR) lasers, where gain is supplied by a thin film active material and the feedback comes from multiple scattering by plasmonic nanoparticles, have shown both low threshold lasing and tunability of the angular and…
Weakly scattering random lasers exhibit lasing modes that spatially overlap and can interact strongly via gain saturation. Consequently, lasing in high-threshold modes may be suppressed by strong low-threshold lasing modes. We numerically…
Coherent combination of emission power from an array of coupled semiconductor lasers operating on the same chip is of fundamental and technological importance. In general, the nonlinear competition among the array supermodes can entail…
Graphene has two very important optical properties of population inversion of electrons, and broadband optical gain. As a result, graphene has potential for use in lasers and amplifiers. In this work, we presented a quantum master model and…
We develop a theory of the propagation and focusing of the THz Gaussian laser beam through the layered superconductor slab of finite thickness in the presence of an external DC magnetic field in a nonlinear regime. We show that, in this…
Formation of a peculiar lasing pattern leading to a TEM00-like mode accompanied by a nonzero bright outer-ring emission (namely, a modified TEM00 mode) was observed in a 300-\mu m-thick LiNdP4O12 (LNP) laser with reflective flat end mirrors…
Weyl semimetals have been intensely studied as a three dimensional realization of a Dirac-like excitation spectrum where the conduction bands and valence bands touch at isolated Weyl points in momentum space. Like in graphene, this property…
The unique sub-grain patterns have been found in some particular alloys (316L, Al-Si, Co-Cr-Mo) selective laser melting (SLM), the submicron-scale cellular, elongated cellular or even band structures are always coexisting inside one single…
For a fully chaotic two-dimensional (2D) microcavity laser, we present a theory that guarantees both the existence of a stable single-mode lasing state and the nonexistence of a stable multimode lasing state, under the assumptions that the…
We present a general analysis for finding and characterizing nonlinear exceptional point (EP) lasers above threshold, using steady-state ab-initio Maxwell-Bloch equations. For a system of coupled slabs, we show that a nonlinear EP is…
Because surface plasmons can be confined below the diffraction limit, metallic lasers that support plasmonic modes can provide miniaturized sources of electromagnetic waves. Such devices often exploit a multilayer design, in which a…
We investigate the topological protection of surface states in Weyl and nodal-line semimetals by characterizing them as evanescent states when the band structure is extended to complex momenta. We find in this way a sequence of exceptional…
Single mode lasing is experimentally demonstrated in a transversely multi-moded InP-based semiconductor microring arrangement. In this system, mode discrimination is attained by judiciously utilizing the exceptional points in a parity-time…
Nonlinear guided wave modes in an asymmetric slab waveguide formed by an isotropic dielectric layer placed on a linear or nonlinear substrate and covered by a hyperbolic material are investigated. Optical axis is normal to the slab plane.…
We present preliminary results from a programme aimed at acquiring linear spectropolarimetry of magnetic A and B stars. Linear polarization in the spectral lines of these objects is due to the Zeeman effect, and should provide detailed new…
We consider a sub-wavelength periodic layered medium whose slabs are filled by arbitrary linear metamaterials and standard nonlinear Kerr media and we show that the homogenized medium behaves as a Kerr medium whose parameters can assume…
Beam profile engineering, where a desired optical intensity distribution can be generated by an array of phase shifting (or amplitude changing) elements is a promising approach in laser material processing. For example, a spatial light…