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Phosphotellurite glass and glass-ceramics with high TeO <sub/>2</sub> content: thermal, structural and optical properties
摘要： Phosphotellurite based glasses have interesting features such as low characteristic temperatures, large glass forming ability, high thermal stability against crystallization and broad transparency window from ultraviolet (UV) to near-infrared (NIR), which makes them promising materials for photonic applications. In this work, phosphotellurite binary glasses, having composition (100 – x) TeO2–x Ba(PO3)2 with x varying from 1 to 20 mol %, were synthesized by the conventional melt-quenching method in covered gold crucibles under air. Optical, physical and structural properties of the new glass samples were investigated by differential scanning calorimetry, X-rays diffraction, Raman spectroscopy, transmission electron microscopy, linear optical absorption from UV to NIR, IR transmittance, and optical limiting experiments. Transparent glass-ceramics in the visible range were obtained for phosphotellurite samples containing 2, 4 and 6 mol % of Ba(PO3)2 and the phase crystallization was investigated through Rietveld analysis and transmission electron microscopy. The incorporation of Ba(PO3)2 into the TeO2 network drastically increases the thermal stability against devitrification and helps to shift the infrared multiphonon absorption edge to longer wavelengths. Nonlinear measurements performed with a picosecond laser at 532 nm indicate large effective nonlinear absorption coefficients for all samples. In summary, the dependence of the spectroscopic properties on the samples’ compositions revealed a promising transparent glass and glass-ceramics for photonic applications.
关键词： transparent glass-ceramics,phosphotellurite glass,optical properties,nonlinear optical response
更新于2025-11-14 17:03:37
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Optical response of a bilayer crystal
摘要： We extend the recently developed classical theory for the optical response of a single-layer crystal to bilayers. We account for the interaction between the two atomic planes and the multiple reflections inside the crystals. We show how to define a global susceptibility meaningful for the bilayer crystal and how its expression varies compared to the single-layer case. We compute both the local and the macroscopic fields, which allow us to make a direct comparison with experimental data.
关键词： local fields,bilayer crystal,optical response,susceptibility,macroscopic fields
更新于2025-09-23 15:23:52
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Nonlinear optical response of a two-dimensional semi-Dirac system in terahertz regime
摘要： We demonstrate a strong nonlinear optical response in a two-dimensional semi-Dirac system in the terahertz regime. By applying the Boltzmann transport theory for the intra-band process and a quantum mechanics method for the inter-band process, we obtained the three-photon current response. It is found that both the intra- and inter-band excitations make significant contributions to the nonlinear response. The third order conductivities (TOCs) σyy(3) are about two magnitudes higher than that of σxx(3). Interestingly, for the inter-band TOCs, there is a sign change when the chemical potential varies across the saddle point in the conduction band in kx direction (that is parabolic), due to the competition between the two opposite nonlinear current contributed by the electrons at states k > kD and k < kD, respectively. Finally, we show that the nonlinear response in terahertz regime is significant at experimentally accessible field strengths. Our results suggest that this system could be of potential applications in photonic device for frequency up-conversion.
关键词： black phosphorous,semi-Dirac system,nonlinear optical response,Boltzmann transport theory
更新于2025-09-23 15:22:29
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Optical Response of Lumped-Element Kinetic-Inductance Detector Arrays
摘要： We present an analysis of the optical response of lumped-element kinetic-inductance detector arrays, based on the NIKA2 1 mm array. This array has a dual-polarization sensitive Hilbert inductor for directly absorbing incident photons. We present the optical response calculated from a transmission line model, simulated with HFSS and measured using a Fourier transform spectrometer. We have estimated the energy absorbed by individual component of a pixel, such as the inductor. The difference between the absorption efficiencies is expected to be 20% from the simulations. The Fourier-transform spectroscopy measurement, performed on the actual NIKA2 arrays, validates our simulations. We discuss several possible ways to increase the absorption efficiency. This analysis can be used for optimization of the focal plane layout and can be extended to other kinetic inductance detector array designs in millimeter, submillimeter, and terahertz frequency bands.
关键词： superconducting microresonator,optical response,millimeter astronomy,Kinetic inductance detector
更新于2025-09-23 15:22:29
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The optical response of self-organized Ag-CdTe metal-semiconductor hybrid nanostructures: Change in interaction vs number density variation
摘要： Using experimental results and a theoretical model, we establish a relation for the optical response of a mixed nanocolloid. We show that colloids prepared by mixing metal and semiconductor nanocolloids in various ratios result in a mixture composed of a particular metal-semiconductor hybrid nanostructure and unattached original particles. Thus, the properties of hybrid samples prepared by such self-organized growth are decided by the variation in number density of the hybrid and the unattached particles and not due to a continuous change in the interaction between metal nanoparticles and semiconductor quantum dots as was assumed earlier. Using these results, a method to prepare a single type of hybrid nanostructure by measuring only its optical response is presented.
关键词： nanoparticles,metal-semiconductor hybrid nanostructures,optical response,quantum dots,self-organized growth
更新于2025-09-23 15:21:21
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Dynamic Response-Based LEDs Health and Temperature Monitoring
摘要： this paper presents a number of novel methods to measure the junction temperature and to estimate the health of gallium nitride light-emitting diodes (LEDs). The methods are based on measurements of the dynamic impedance and optical output. Our experimental analysis reveals temperature sensitive parameters of the electrical and optical responses. Moreover, a correlation between the non-radiative current characterizing the defects in the active region and the small-signal impedance is demonstrated. The demonstrated methods can be applied to enhance existing techniques. The temperature-monitoring derived dependencies also build a foundation for advanced in-field monitoring health of the LEDs and for prediction of imminent failures using the infrastructure of visible light communication systems. Such models are valuable for predictive maintenance.
关键词： smart driver,failure modes,temperature,impedance,OWC,electrical response,optical response,defects,LED,reliability
更新于2025-09-23 15:19:57
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Second-Harmonic Generation from a Quantum Emitter Coupled to a Metallic Nanoantenna
摘要： We use time-dependent density functional theory and a semiclassical model to study second-harmonic generation in a system comprising a quantum emitter and a spherical metallic nanoparticle, where the transition frequency of the quantum emitter is set resonant with the second harmonic of the incident frequency. The quantum emitter is shown to enable strong second-harmonic generation, which is otherwise forbidden because of symmetry constraints. The time-dependent density functional theory calculations allow to identify the main mechanism driving this nonlinear effect, where the quantum emitter plays the role of an optical resonator that experiences the nonlinear near fields generated by the metallic nanoantenna located nearby. The influence of the intrinsic properties of the quantum emitter and the nanoantenna, together with the relative position of both in the coupled system allows for a high degree of control of the nonlinear light emission. The main effects and contributions to this nonlinear process can be correctly captured by a semiclassical description developed in this work.
关键词： quantum emitter,plasmonics,nonlinear optical response,Second-harmonic generation,electromagnetic coupling
更新于2025-09-23 15:19:57
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Semiconducting Polymer Dots as Broadband Saturable Absorbers for Q-switched Fiber Lasers
摘要： Semiconducting polymer dots (Pdots) have attracted much attention due to their outstanding optical properties. However, Pdots potential in laser technology is rare. Here, we first report the benzobisthiadiazole (BBT)-based Pdot as a single broadband nonlinear saturable absorber (SA) for passively Q-switched fiber lasers at 1, 1.5, and 2 μm. The Pdots-SA possesses a strong saturable absorption, broadband nonlinear optical response, and large modulation depth. Once the Pdots-SA is integrated into the ytterbium-, erbium-, and thulium-doped fiber laser cavities, stable Q-switched operations are observed at the central wavelengths of 1036, 1561, and 1951 nm. Our results verify that the Pdots are promising nonlinear media for Q-switched pulses generation, and highlight the potential of Pdots for relevant nonlinear optical applications.
关键词： Saturable absorber,Semiconducting polymer dots,Q-switched fiber lasers,Broadband nonlinear optical response
更新于2025-09-23 15:19:57
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Graphene Photonics || Nonlinear Optical Properties
摘要： In the preceding two chapters, we consider only the linear optical response of graphene; fields of different frequencies do not mix, and the amplitude of the response is linearly proportional to the strength of the excitation optical field. In this chapter, the nonlinear optical response of graphene is discussed. In general, the nonlinear optical response of a material is described by a polarization that is a nonlinear function of the optical field; such a nonlinear polarization is characterized by a nonlinear susceptibility. Because graphene can be treated as a conductor, its nonlinear optical response can alternatively be described by an optical current that is a nonlinear function of the optical field; such a nonlinear current is characterized by a nonlinear conductivity. As in the case discussed in the preceding two chapters for the relation between linear susceptibility and linear conductivity, these two alternative descriptions of nonlinear optical properties of graphene are equivalent. In this section, we first define the nonlinear susceptibility and then make the connection between the nonlinear susceptibility and the nonlinear conductivity.
关键词： Optical Response,Nonlinear Conductivity,Graphene,Nonlinear Optical Properties,Nonlinear Susceptibility
更新于2025-09-16 10:30:52
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Synthesis of Perovskite CsPbBr <sub/>3</sub> Quantum Dots/Porous Boron Nitride Nanofiber Composites with Improved Stability and Their Reversible Optical Response to Ammonia
摘要： All-inorganic CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) have great potential for various applications due to their excellent photoluminescence properties. However, poor stability under long-term storage hinders their applications. Herein we report the utilization of porous boron nitride nanofibers (BNNFs) as a promising carrier for anchoring of CsPbBr3 QDs. Due to the good dispersion and immobilization of CsPbBr3 QDs, the resulting CsPbBr3/BNNF composites show excellent photostability and superior long-term storage stability in an air environment. Moreover, the CsPbBr3/BNNF composites exhibit an interesting ammonia-responsive behavior: i.e., a distinct decrease in photoluminescence intensity upon exposure to ammonia gas and the subsequent photoluminescence recovery after post-treatment in nitrogen gas. Even after treatment with ammonia gas for 3 h, the composites can still be recovered under nitrogen gas treatment. The fast response, reversibility, and stability of CsPbBr3/BNNF composites in the presence of ammonia gas could inspire a broader range of applications.
关键词： photostability,reversible optical response,perovskite quantum dots,boron nitride nanofibers,ammonia-responsive behavior
更新于2025-09-12 10:27:22