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Photonic crystals (PhCs) fabricated in the bulk of dielectric media have already been demonstrated to show a low-pass spatial (angular) filter functionality. [1] These PhC filters are fabricated in inorganic glasses through a femtosecond laser writing process. The most promising aspect of such filters is their direct integration into the cavities of laser micro-resonators. In particular, the integration...
Generating correlated photons is an essential technology for photonic quantum information experiments. Increasing the generation efficiency of photon pairs via the enhancement of material nonlinearity is important for various applications including a near-on-demand single photon source based on multiplexed photon pair sources [1]. In this regard, photonic crystal nanocavities are attractive nonlinear...
Optically confined structure is a fundamental topic in both basic and applied physics including potential application in information engineering, biological and medical sciences, sensing. In this scenario one-dimensional photonic crystals have been widely investigated and still remain an outstanding tool for new photonics, being the simplest system to exhibit a so-called photonic bandgap and therefore...
In recent years a novel direction of optical research is being developed — optics of parity-time-symmetric (PT-symmetric) media [1]. The similarity between the quantum-mechanical Schrodinger equation for the complex potential and the wave equation for the electric field in the medium possessing complex permittivity, i.e. in the medium with gain and loss, enabled extrapolating results, obtained from...
Frequency conversion from the telecom range into the visible is demonstrated in suspended GaN slab photonic crystal (PhC) cavities through second harmonic generation (SHG) and third harmonic generation (THG), under continuous-wave resonant excitation. PhC cavities based on L3 and H0 designs are implemented with embedded injectors, the latter shown in Fig. 1a, enabling improved coupling to the fundamental...
Photonic crystals (PhCs) provide light trapping properties that allow people to control the flow of light, and three dimensional PhCs have been proposed as the most efficient light trapping microstructures [1]. The photonic band structure is the most important optical property of a PhC, which describes the dispersion relation for propagating modes within the structure. By measuring the bandstructure...
In nanofabrication, it is a major challenge to characterize the structure of a real sample, in particular of three-dimensional (3D) ones that control non-linear optics or quantum dot emission [1]. The challenge notably pertains to nanophotonic media whose properties are determined by their complex structure with feature sizes d comparable to or even less than the wavelength of light (d<2). These...
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)...
Barium titanate (BaTiO3) is a perovskite crystal, which is transparent over a wide spectral range and has a high refractive index. BaTiO3 is a suitable building block for metamaterials or photonic devices. In addition, BaTiO3 emits a strong second harmonic generation (SHG) signal due to its noncentrosymmetric crystal structure. SHG in nanostructures has potential applications in bio-imaging and lab-on-a-chip...
Photonic crystals have been used to provide fundamental control over the interaction between light and matter, including stimulated emission. For example, in Bloch-mode lasers, the photonic crystal provides field enhancement through reduced group velocity and offers larger mode volumes through distributed feedback [1]. In a photonic free-electron laser (pFEL) [2], where electrons stream through a...
Slow light is a phenomenon explained by low group velocity of the pulsed light. Faraday effect can be greatly enhanced in multilayered structures due to the artificial dispersion [1, 2]. Magnetophotonic crystals, as being layered nanostructures, can modulate electric filed amplitude and phase of a femtosecond pulse in time. For example, Faraday angle at the initial part of the pulse can differ from...
The interaction of light with suitably designed artificial nanostructures, such as metasurfaces or photonic crystals, can lead to a strong chiral response. Such chirality is not only essential for realizing miniature components to manipulate polarization, but also opens new avenues in chiral sensing, emission control, and topological photonics. An extreme possible consequence of a system's chirality...
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).
Photonic crystals (PCs) are artificial wavelength-scale periodic structures that enable the manipulation of light propagation and possess intriguing dispersive characteristics such as super-prism, negative refraction, and slow/fast light [1]. Besides all these properties, self-collimation phenomenon is another anomalous dispersive property of PCs that provides the existence of non-diffracting Bloch...
There has recently been great interest in chiral waveguides, where the polarisation of the forwards and backwards propagating light fields are oppositely circular at certain positions in space (C-points) [1]. This results in new phenomena, such as the one way emission of light from spin-transitions in quantum dots (QDs) or atoms (simulation, fig. b). The emitted photon's direction is determined by...
Light propagates inside an ideal and infinite photonic crystal when the Bloch condition is satisfied and any allowed light wave is decomposed in a basis of propagating Bloch waves [1]. In real photonic crystals, light propagation is modified due to unavoidable fabrication-induced structural imperfections in size, positions, and permittivity of the building blocks, as well as the finite size of the...
Photonic Crystal Slabs (PCSs) are nanostructured, dielectric waveguides that feature resonances with small bandwidths and very high reflectivity in the visible spectrum. As refractive index-sensitive transducers, PCSs have been studied for biosensing applications in the past decades [1]. Incident light can couple to and from quasi-guided modes at resonance wavelengths. Due to the evanescent field...
The efficiency and engineering capabilities afforded by parametric processes in second-order [χ(2)] nonlinear media have tremendously benefitted from periodic poling technologies in ferroelectric materials such as LiNbO3, nowadays routinely exploited in optical parametric generators, amplifiers and oscillators, as well as high brightness sources of entangled photons [1, 2]. Nonlinear photonic crystals...
Monolayer Transition Metal Dichalcogenides (TMDs) have recently attracted great interest in the field of photonics because of their distinctive optical and spin properties. In contrast to bulk TMD materials, which are indirect bandgap semiconductors, monolayer TMDs are highly optically active due to a direct bandgap ranging between 1 and 2 eV [1]. The coupling of TMD excitons to optical fields can...
Pure and deterministic single-photon sources, obtained by coupling a semiconductor quantum dot (QD) to a photonic crystal (PhC) cavity, constitute a key component for quantum photonic integrated circuits (QPICs) [1]. These sources are commonly excited by a laser pump, which involves some practical limitations in scaling the number of integrated cavity-emitter nodes and is hardly compatible with on-chip...
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