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The discovery of intersubband transitions in III-V semiconductor heterostructures [I] had a huge impact on large parts of the condensed matter physics community and ultimately led to the development of quantum well infrared photodetectors [2] and quantum cascade lasers [3]. One of the main constraints, however, are the strict lattice matching conditions of the heterostructures — limiting the available...
Remarkable advances in cooling and manipulating atomic gases have opened up new avenues to explore fundamental concepts in quantum many-body physics. Synthetically created potentials and control of atom-atom interactions have made it possible to tailor the properties of experimental systems at a microscopic level. This led to the concept of quantum simulation — here a system capable of reproducing...
Novel nonlinear optical crystals have attracted considerable interests due to their wide applications in frequency shifting, terahertz generation, optical communications, display, sensing, and so on. Because terahertz radiation is sensitive to free carriers and lattice vibrations in solid states, terahertz time-domain spectroscopy (THz-TDS) has become a pivotal tool in investigating fundamental dynamics...
It is well known that photons carrying momentum ħk exert a positive pressure on an object in vacuum. However, whether photons push or pull an object immersed inside a dielectric medium is not so straightforward due to the century-old debate associated with the definition of photon momentum inside dielectrics [1-2]. This question becomes even more puzzling with the advent of metamaterials, which can...
Surface plasmon polaritons (SPPs) in plasmonic metal waveguides can excite a third-order nonlinear response [1] much akin the well-known self-phase modulation (SPM) and two-photon absorption seen in light propagating in dielectric waveguides. In metals, the nonlinearity mainly arises as a self-acting effect: after absorption of the incident light the nonlinearity arises due to hot-electron contributions...
The I-SOC (Space Optical Clock on ISS) mission [1] is an ESA mission whose main goal is testing the Einstein Equivalence Principle and performing relativistic geodesy from space. It will be based on a strontium lattice clock on the ISS, which will be compared with ground clocks using advanced frequency link technologies, optical and microwave. The space clock will have 1×10−17 fractional inaccuracy,...
Manipulation of perovskite crystallinity in order to obtain the desired optoelectronic properties is a critical issue. Perovskite structural characterization has been carried out applying several tools, which usually interrogate bulky portions of the material, averaging out over the inhomogeneities at the sub-micron scale [1]. Preliminary results obtained through photoluminescence microscopy across...
Optical vortex or orbital angular momentum (OAM) of light are a subject of active research and have been employed for novel applications such as optical manipulation, quantum information and control of cold atoms [1]. For decades, it has been discussed if OAM of light could affect the state of a bound system of charges such as an atom or a molecule, an exchange should arise between light and matter,...
Crystalline silicon, used as a base material in the electronics industry, has been widely investigated in a variety of fields; particularly, nano- or micro-structured crystalline silicon will act as a fundamental element for photonics, photonic crystals, and solar cells.
The recent findings of line narrowing in Raman-active continuous-wave-pumped gas [1] showed that the Stokes scattering occurs in a Lamb-Dicke regime and is associated to formation of array of deep subwavelength nanotraps, which resulted in a sub-recoil linewidth Stokes radiation [1]. The results also showed that this nanotrap lattice exhibits a macroscopic motion. Here we present theoretical and numerical...
Last years have seen the emergence of a new class of hollow-core photonic crystal fibers (HC-PCF) no longer relying on photonic bandgap guidance but on inhibited-coupling (IC) mechanism. The first specie of this fiber family took the form of Kagome-lattice [1]. The guiding rule for enhancement of such a guidance (minimizing the coupling between the core mode and cladding mode, i.e (φclad |Δn2| φcore...
A superposition of two optical vortices with different topological charges forms a light wave with azimuthally periodic structure. The beam with such rotational symmetry is called a ring-shaped optical lattice [1]. One of its important features is that it can be flexibly rotated by controlling relative phase difference between them without changing its structure, which offers us rotational degree...
Nonlinear photonic crystals such as 2D-PPLT (periodically-poled lithium tantalite) are of great interest for multi-wavelengths frequency conversion thanks to the contribution of different reciprocal lattice vectors (RLV) [1]. Such characteristics facilitates optical parametric generation (OPG), second harmonic generation (SHG), sum-frequency generation (SFG) or difference frequency generation (DFG)...
In this contribution, we demonstrate that a periodic lattice of frequency-detuned and displaced resonant rods can suppress the THz extinction at the central resonant frequency, leading to an enhanced spectral window of near perfect transparency [1], as shown in Fig. 1(a). The system consists of a periodic lattice of metallic rods of two different sizes as shown in the inset of Fig. 1(a). Each of the...
The signal wavelength of collinear direction is enhanced at two quasi-collinear directions with the generation of two idler wavelengths thanks to simultaneous contribution of reciprocal lattice vectors Km, n in a two-dimensional nonlinear photonic crystal (2D-NLPC).
Sesquioxides have been identified as having great potential for use as host materials for lasers due to their exceptional thermomechanical and optical properties as well as crystallographic properties well suited to the incorporation of rare-earth dopants [1]. However, fabrication of sesquioxide hosts is challenging due to their high melting points (>2400°C), making it difficult to grow high-quality...
Quantum cascade lasers (QCLs) are powerful sources of coherent radiation covering the frequency range from mid-infrared to terahertz. In the terahertz frequency range the active region is normally realized using a GaAs/AlxGa1−xAs semiconductor heterostructure. This material system enables a variable conduction band offset by changing the Al-content in the barrier layers without introducing a significant...
Manipulating the flow of light with unusual diffraction features has been enabled, during the last decades, by considering optical transport in structured photonic media. The analogy between solid-states physics and the light propagation in specifically engineered arrayed structures generally leads to gapped dispersion relations. More recently, photonics borrowed concepts from topological insulators...
The topology of a gapped band structure is characterised by a bulk invariant and is deeply related to the existence of gapless edge modes through a principle known as bulk-edge correspondence. This correspondence has allowed to evidence topological phases by probing edge properties. Nonetheless, some experiments based on optical lattices of cold atomic gases have reported the possibility to directly...
Since the first observation of Airy beam in 2007, its propagation properties, such as self-acceleration, self-healing and reflection/refraction, have been studied widely [1, 2]. Based on these achievemnts, with the development of photonic lattices, the studies of Airy beam have been spread from homogeneous meduim to periodic structures. In photonic lattices, researchers demonstrate that the accelerating...
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