- 标题
- 摘要
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- 实验方案
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Optical Characterization of Doped Thermoplastic and Thermosetting Polymer-Optical-Fibers
摘要： The emission properties of a graded-index thermoplastic polymer optical fiber and a step-index thermosetting one, both doped with rhodamine 6G, have been studied. The work includes a detailed analysis of the amplified spontaneous emission together with a study of the optical gains and losses of the fibers. The photostability of the emission of both types of fibers has also been investigated. Comparisons between the results of both doped polymer optical fibers are presented and discussed.
关键词： polymer optical fibers,thermoplastic fibers,rhodamine 6G,light-emitting polymers,optical gain,amplified spontaneous emission,thermosetting fibers
更新于2025-11-14 15:30:11
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Efficient optical gain in CdSe/CdS Dot-in-Rod nanocrystals
摘要： Excitonic state-resolved pump/probe spectroscopy is performed on semiconductor dot-in-rod nanocrystals. Using excitonic state-resolved pumping we are able to resolve effects of the rod upon exciton dynamics of the core. The shell has the effect of lowering gain threshold, increasing absorption cross-section, and increasing the Auger lifetime, hence nanorods are shown to be an effective means of enhancing gain performance of nanomaterials.
关键词： nanocrystal,excitons,Auger processes,Quantum dot,optical gain,multiexcitons.
更新于2025-09-23 15:23:52
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Inducing tunable single-mode operation of Fabry-Perot semiconductor laser coupled with very-short cavity with selective optical feedback
摘要： We report on achieving tuned single mode operation of a multimode semiconductor laser by coupling it to a very-short external cavity with selective feedback. We show that the induced uniform feedback light from the very-short external cavity can induce single-mode oscillation over a broad range of optical feedback. Then by applying selective external to the optimum settings of the single-mode oscillation, we predict tuning of the single-mode output over a wavelength range of ~ 20 nm by detuning the peak wavelength of optical feedback from the central wavelength of the modal gain. The study is based on modeling of the dynamics of multimode semiconductor laser subject to selective optical feedback. The model takes into account mechanisms of both self- and cross-modal gain suppression, and the study is concerned with the very-short external cavity that corresponds to stable continuous-wave (CW) operation.
关键词： Optical feedback,Semiconductor laser,Multimode laser,Optical gain
更新于2025-09-23 15:21:01
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Pulsed Laser Photopatterning of Cesium Lead Halide Perovskite Structures as Robust Solutiona??Processed Optical Gain Media
摘要： Solution-processed optical gain media such as thin films of colloidal semiconductor nanocrystals promise ease of fabrication and scalable production while offering a spectrally wide range of emission colors. However, depositing such gain media in a size- and shape-specific manner at a precise location on a substrate can be highly challenging. In this work, a facile approach for fabricating solution-processed cesium lead halide perovskite structures of any arbitrary shape and size from their nanocrystal counterparts via a pulsed laser photopatterning process is demonstrated. The photopatterned structures resist solvation in both polar and nonpolar solvents, allowing for the straightforward removal of unpatterned regions. Their robustness is attributed to the ligand-removal, sintering, and photoannealing of the nanocrystals at the site of irradiation. Concomittantly, the photopatterning process results in lengthened Auger-dominated biexciton lifetimes and larger absorption cross-sections that permit relatively low amplified spontaneous emission thresholds. It is shown that the photopatterning process may be used to fabricate cesium lead halide based gain media capable of multiwavelength emission, orientation-dependent wavelength of emission, as well as functional operation while fully immersed in various solvents. It is envisioned that the photopatterning process may be extended to other perovskite systems to include applications beyond those requiring light-emission.
关键词： sintering,amplified spontaneous emission,pulsed laser photopatterning,colloidal perovskites,optical gain media
更新于2025-09-23 15:21:01
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[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || Optimization of AlGaN QW Heterostructure for UV Applications
摘要： This paper reports the existence of ultraviolet (UV) optical gain in AlN/AlGaN/AlN nanoscale heterostructure consisting of 50 nm quantum well (QW) of AlGaN material sandwiched between layers of AlN material. The designed heterostructure is of type-I and assumed to be grown on GaN substrate. The optical gain of the heterostructure has been optimized utilizing k.p method. The simulation result shows that the peak optical gain in the AlGaN QW heterostructure lies at ~2400 ? (UV region) of the order of ~760 cm, which proves the potentiality of the AlN/AlGaN/AlN heterostructure as a source of UV radiations.
关键词： Type-I heterostructure,AlN,Optical gain,AlGaN
更新于2025-09-23 15:21:01
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Phenomena of Optical Metamaterials || Active Optical Metamaterials
摘要： At the turn of the century, a new field of research emerged at the crossing between physics, electrical engineering, and materials science. The study of metamaterials addresses the rational design and arrangement of a material’s building blocks to attain physical properties that may go significantly beyond those of its original constituent materials. Most often, the concept of metamaterials is associated with electromagnetic wave propagation, where the engineering of resonant subwavelength structures allows for the precise control of effective wave properties. It is this advanced functionality that enables the realization of unique wave phenomena, such as the focusing of light below the diffraction limit or electromagnetic cloaking of objects—concepts that have captured the imagination of researchers and the general public alike. Importantly, the element of functionality is an integral part of the metamaterial concept.
关键词： nanoplasmonics,plasmonics,negative refractive index,optical gain,metamaterials
更新于2025-09-23 15:21:01
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Deepa??Blue Thiophenea??Based Steric Oligomers as a Lowa??Threshold Laser Gain and Host Material
摘要： Thiophene-based (Th-based) derivatives have received wide attentions in organic optoelectronics due to their excellent and tuneable optoelectrical properties as well as chemical modification. However, the low photoluminescence quantum yield in solid state limits their application in solution-processed light-emitting optoelectronic devices, especially in organic lasers. Herein, a novel blue-emitting steric Th-based fluorophore (MC8-Th) with excellent optical gain behavior for organic laser is reported. Interestingly, MC8-Th neat film exhibits efficient exceptional deep-blue amplified spontaneous emission (ASE) behavior with a remarkably low threshold of 6.0 μJ cm?2 and full-width-at-half-maximum value of 2.6 nm. Furthermore, random laser signals are also obtained with the lowest threshold of 4.1 μJ cm?2 when incorporating the compound into an inert polystyrene (PS) matrix. In addition, low threshold (16 μJ cm?2, fivefold lower than those of F8BT neat films) yellow–green ASE emission (560 nm) is achieved through F?rster resonance energy transfer. Meanwhile, ultrafast transient absorption spectroscopy is deployed here to observe the single-molecular excitonic behavior in solution and PS-blend, intermolecular excited state in neat film, and efficient energy transfer in MC8-Th:F8BT-blend films. As far as known, MC8-Th shows lower threshold ASE/lasing behavior for the Th-based conjugated materials.
关键词： transient absorption spectroscopy,optical gain behavior,organic laser,thiophene-based derivatives,F?rster resonance energy transfer
更新于2025-09-23 15:19:57
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Multilayer plasmonic photonic structures embedding photochromic molecules or optical gain molecules
摘要： We study the optical properties of different functional molecular systems in order to embed them in properly designed photonic structures for photochromic switching and lasing. We study the light absorption of two photochromic molecules and of 4,4’-bis[(N-carbazole)styryl]biphenyl (BSB-Cz) with density functional theory. For the photochromic diarylethene we derivate the refractive index with Kramers-Kronig relations and we design multilayer photonic structures alternating diarylethene with either poly vinyl carbazole or fluorine indium co-doped cadmium oxide (FICO) nanoparticle-based layers. For BSB-Cz we design a one-dimensional photonic crystal alternating BSB-Cz layers wit SiO2 layers and a microcavity embedding BSB-Cz between indium tin oxide (ITO) / FICO nanoparticle-based multilayers.
关键词： multilayer plasmonic photonic structures,photochromic molecules,density functional theory,Kramers-Kronig relations,optical gain molecules
更新于2025-09-23 15:19:57
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Low-threshold stimulated emission in perovskite quantum dots: single-exciton optical gain induced by surface plasmon polaritons at room temperature
摘要： Colloidal perovskite quantum dots are candidate materials for solution-processable lasers, although stimulated emission in a semiconductor usually occurs in the multiexciton regime. Due to the quantum-confinement effect of semiconductor quantum dots, the non-radiative recombination transition dominates the relaxation of multiexcitons. Hence, the implementation of low-threshold stimulated emission of perovskite quantum dots in the single-exciton regime is meaningful. Herein, we show that this problem can be partially solved by employing a locally enhanced electric field. By applying the metal surface plasmon resonance energy-transfer effect, we demonstrate a considerable reduction of the optical gain threshold due to the newly generated coupling level induced by the local surface plasmon, and obtain optical gain in the single-exciton regime at room temperature in colloidal perovskite quantum dots. At the same time, we achieve a more than fourfold reduction in the amplified spontaneous emission threshold. This may provide a new concept for the further design of low-threshold stimulated emission colloidal nanocrystal lasers and even for improving their energy conversion efficiency.
关键词： surface plasmon polaritons,stimulated emission,optical gain,room temperature,perovskite quantum dots
更新于2025-09-23 15:19:57
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Enhancement of the optical gain in GaAs nanocylinders for nanophotonic applications
摘要： Semiconductor nanolasers based on microdisks, photonic crystal cavities, and metallo-dielectric nanocavities have been studied during the last few decades for on-chip light source applications. However, practical realization of low threshold, room temperature semiconductor nanolasers is still a challenge due to the large surface-to-volume ratio of the nanostructures, which results in low optical gain and hence higher lasing threshold. Furthermore, the gain in nanostructures is an important parameter for designing all-dielectric metamaterial-based active applications. Here, we investigate the impact of p-type doping, compressive strain, and surface recombination on the gain spectrum and the spatial distribution of carriers in GaAs nanocylinders. Our analysis reveals that the lasing threshold can be lowered by choosing the right doping concentration in the active III–V material combined with compressive strain. This combination of strain and p-type doping shows 100× improvement in gain and approximately five times increase in modulation bandwidth for high-speed operation.
关键词： surface recombination,optical gain,compressive strain,GaAs nanocylinders,nanophotonic applications,p-type doping
更新于2025-09-23 15:19:57