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The recent intense research in the newly founded area of PT-symmetric optics [1,2] has triggered a lot of attention in theoretical and experimental studies of non-Hermitian effects in photonics. In this context of composite photonic systems that contain gain and loss, we recently demonstrated for the first time the existence of so-called “constant-intensity waves” (or CI-waves) [3], which, in the...
There are materials which their nonlinear refractive index (n2) have contributions from fast isotropic and slow reorientational effects. Due to the presence of the slow noninstantaneous effect, the magnitude of the effective nonlinear refractive index (n2, eff) depends of the pulse width (τ). Here, we propose to measured the n2eff of several organic solvents as a function of pulse width and from these...
We investigate the possibility of slowing down terahertz light via intersubband transitions in quantum well heterostructures. The slow-down effect is achieved via tunneling induced transparency [1] in a three level Λ-system by careful engineering of the wave functions [2]. The inherently short coherence times in such solid state media inevitably leads to strong absorption of the signal, which we propose...
We present, for the first time, the results regarding the production of refractive index (RI) sensors, through the acousto-optic effect in tilted fiber Bragg gratings (TFBGs). The RI is analysed in detail when acoustic waves are turned on using saccharose solutions with different RI from 1.3327 to 1.4249.
Optical diffraction tomography provides a powerful tool for imaging the 3-D refractive index (RI) distribution. However the method suffers from two major issues. The first one is the missing cone problem that comes from limited illumination angles. The missing cone problem can be dealt with sparsity based regularization [1]. The second problem is the nonlinear relationship between the refractive index...
Femtosecond laser waveguide writing is a powerful technique to create photonic devices and is already widely applied in glasses and crystals [1]. In polymers however, relatively little work has been reported so far. Material specific effects during femtosecond laser irradiation such as chain scission or crosslinking and an overall low damage threshold demand for alternative writing schemes to overcome...
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...
Integrated Optical Fibre (IOF) is a passive optical platform that directly integrates optical fibre to a planar substrate, illustrated in Fig 1(a). It possess advantages associated with optical fibre such a low propagation loss, whilst enabling planar functionality commonplace with integrated optics. Planarization is uniquely achieved through a modified Flame Hydrolysis Deposition (FHD) technique...
Single-photon sources are key components in applications of photonic quantum technologies such as quantum key distribution (QKD) [1]. One way of realizing single-photon sources is generation of photon pairs (PP) using spontaneous four-wave mixing (FWM): two photons from a pump p annihilate and create two side-band photons at frequencies determined partly by the energy conservation 2ωρ = ω1 + ω2, where...
Using Terahertz (THz) time-domain spectroscopy (THz-TDS), the dispersion of several gases had been measured up to 4.5 THz [1]. From these measurements the refractive index that increases with increasing pressure was obtained over this frequency range. The results follow the Hauf-Grigull relation.
In recent years, all-solid photonic bandgap fibers (AS-PBFs) have attracted great attentions since they can be applied to many devices such as tunable filters, optical modulators, fiber lasers, amplifiers and sensors [1]. The AS-PBF is related to an optical fiber whose cladding consists of an arrangement of isolated high-index rods in a low-index background [2]. The fiber core of an AS-PBF locates...
Microelectromechanical systems (MEMS) currently see a trend towards inclusion of optical functionalities, i.e., towards microoptoelectromechanical systems (MOEMS). However, typical MEMS materials such as silicon, silicon oxide and silicon nitride limit the choice of available refractive indices and spectral operating regions. Particularly, a low refractive index material is highly desirable which...
By simultaneously controlling the electric and magnetic properties of a nanostructured composite material (metamaterial), we can create materials with a refractive index of zero. We present a novel on-chip platform to explore zero-index metamaterials.
Metallic colloids can confine and focus light below the diffraction limit, leading to interesting properties and applications, such as metamaterials and sensors. However, accurate knowledge of the refractive indices of these colloids is critical to develop their unique optical properties. Anisotropic colloids, such those with Au nanorods (NRs) can be aligned with external electric fields, thus dynamically...
Gradient index (GRIN) fibers have recently been identified as the potential next generation components for today's classic fiber optic applications, ranging from telecommunications to laser technologies [1]. In particular the nonlinear beam self-cleanup leading in multimode (MM) GRIN fibers to spatial organization into a fundamental mode on a weak background of higher order modes, is hoped to disrupt...
Nanoscale light emitters, such as nanocrystals, organic molecules, and color centers in solids, offer a wide range of opportunities for applications. However, light cannot be easily collected from such systems due to radiation at wide angles and total internal reflection, especially when the refractive index of the host medium is large. Typically, advanced optical nanostructures and/or sophisticated...
The Nonlinear interaction between counterpropagating light has attracted significant attention in the context of unidirectional lasing in ring resonators and in nonlinear loop mirrors. In this work we demonstrate that Kerr-nonlinearity-mediated interaction between counterpropagating light in a passive ultra-high-Q microresonator can produce spontaneous symmetry breaking. When sending light of the...
Single-ring hollow core photonic crystal fibre (SR-PCF) has created much interest over the past several years because of the simplicity of the structure, relatively low transmission losses and broad guidance bands. SR-PCF consists of a ring of thin-walled capillaries (inner diameter d) arranged symmetrically around a central hollow core (diameter D). It has been shown that if d/D = 0.682, the LPci-like...
It is known that an acoustic/elastic wave propagating along an optical fiber has the capability to produce coupling between optical fiber modes. A variety of all-fiber, dynamic, and reconfigurable components based on this effect has been demonstrated over the last decades [1]. In the last years, acousto-optic (AO) interaction has been proved to be a powerful and highly sensitive method for the characterization...
The growing demand for high power fiber lasers and the need for higher and higher cw-output powers pose new challenges to fiber technologists. The fabrication of suitable low-NA fibers in the materials system of choice, Yb, Al, P-doped silica, is challenging. Hence, new, facilitating fabrication methods are required. In this contribution we report on fabrication principles of a promising alternative...
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