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Transverse mode instabilities are a major limitation for power scaling of fiber lasers but have so far only been observed in laser-active fibers. In this contribution we present experimental observations of transverse mode instabilities in a passive fiber. [https://www.selleckchem.com/products/rbn013209.html check details] In this fiber, stimulated Raman scattering acted as heat source. To demonstrate the effect, a kW-level ytterbium-doped fiber laser was used as pump for a Raman amplifier. Transverse mode instabilities were only observed in the case with high Raman amplification. Frequency resolved stability measurements at various fiber positions as well as spectral and mode resolved measurements pin their origin to the passive fiber. This observation might help to gain further understanding of transverse mode instabilities and shows limitations of high-power Raman amplifiers.Scattering affects excitation power density, penetration depth and upconversion emission self-absorption, resulting in particle size -dependent modifications of the external photoluminescence quantum yield (ePLQY) and net emission. Micron-size NaYF4Yb3+, Er3+ encapsulated phosphors (∼4.2 µm) showed ePLQY enhancements of &gt;402%, with particle-media refractive index disparity (Δn) 0.4969, and net emission increases of &gt;70%. In sub-micron phosphor encapsulants (∼406 nm), self-absorption limited ePLQY and emission as particle concentration increases, while appearing negligible in nanoparticle dispersions (∼31.8 nm). These dependencies are important for standardising PLQY measurements and optimising UC devices, since the encapsulant can drastically enhance UC emission.Due to the negative coefficient of thermal expansion of graphene, temperature changes of graphene-coated photonic surfaces could induce resonant mode shifts in diffractive optical absorptance and emission. This study focuses on the modification of optical properties through folding, or "origami," of graphene covering a plasmonic metal channel grating. This work is especially critical to understanding tailored deep plasmon emission from geometrically-modulated conducting sheets such as graphene. Conformational changes in graphene on gratings are found to tailor cavity resonance emission and plasmonic oscillations such as magnetic polaritons (MPs) and surface plasmon polaritons (SPPs), respectively. Up to 46% reduction in radiative absorptance was observed through retarded MP. Excited SPP modes can increase narrowband absorptance of 0.5 through folding of graphene. Tailoring of optical absorptance can be used for applications such as photodetectors and thermal emitters.Multifold wave-particle quantum correlations are studied in strongly correlated three-photon emissions from the Mollow triplet via frequency engineering. The nonclassicality and the non-Gaussianity of the filtered field are discussed by correlating intensity signal and correlated balanced homodyne signals. Due to the non-Gaussian fluctuations in the Mollow triplet, new forms of the criterion of nonclassicality for non-Gaussian radiation are proposed by introducing intensity-dual quadrature correlation functions, which contain the information about strongly correlated three-photon emissions of the Mollow triplet. In addition, the time-dependent dynamics of non-Gaussian fluctuations of the filtered field is studied, which displays conspicuous asymmetry. Physically, the asymmetrical evolution of non-Gaussian fluctuations can be attributed to the different transition dynamics of the laser-dressed quantum emitter revealed by the past quantum state and conditional quantum state. Compared with the conventional three-photon intensity correlations that unilaterally reflect the particle properties of radiation, the multifold wave-particle correlation functions we proposed may convey more information about wave-particle duality of radiation, such as the quantum coherence of photon triplet and "which-path" in cascaded photon emissions in atomic systems.In this paper, two different display modes, the "pinhole mode" and the "lens mode" of the pinhole-type integral imaging (PII) based hologram are demonstrated by proper use of random phase. The performances of resolution, fill factor and image depth, of the two display modes are analyzed. Two different methods, the moving array lenslet technique (MALT) and the high-resolution elemental image array (EIA) encoding are introduced for the spatial resolution enhancement of the two display modes, respectively. Both methods enhance the spatial resolution without increasing the total pixel number or the space-bandwidth product (SBP) of the hologram. Both simulation and optical experiments verify that the proposed methods enhance the spatial resolution of PII-based hologram at a very low cost.Phase-sensitive nonlinear gain processes have been implemented as noise-reduced optical amplifiers, which have the potential to achieve signal-to-noise ratios beyond the classical limit. We experimentally demonstrate a novel phase-sensitive four-wave mixing amplification process in a single atomic vapor cell with only two input frequencies and two input vacuum modes. The amount of phase sensitivity depends on the power ratio between the inserted probes as well as on the input frequency of the probes. We find that, for certain phase values, the intensity noise of an output mode is lower than that of its phase-insensitive counterpart.The concept of "cloaking" an object is a very attractive one, especially in the visible (VIS) and near infra-red (NIR) regions of the electromagnetic spectrum, as that would reduce the visibility of an object to the eye. One possible route to achieving this goal is by leveraging the plasmonic property of metallic nanoparticles (NPs). We model and simulate light in the VIS and NIR scattered by a core of a homogeneous medium, covered by plasmonic cloak that is a spherical shell composed of gold nanoparticles (AuNPs). To consider realistic, scalable, and robust plasmonic cloaks that are comparable, or larger, in size to the wavelength, we introduce a multiscale simulation platform. This model uses the multiple scattering theory of Foldy and Lax to model interactions of light with AuNPs combined with the method of fundamental solutions to model interactions with the core. Numerical results of our simulations for the scattering cross-sections of core-shell composite indicate significant scattering suppression of up to 50% over a substantial portion of the desired spectral range (400 - 600 nm) for cores as large as 900 nm in diameter by a suitable combination of AuNP sizes and filling fractions of AuNPs in the shell.