- 标题
- 摘要
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- 实验方案
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Observation of stimulated emission from Rhodamine 6G-polymer aggregate adsorbed at foam interfaces
摘要： This paper reports for the first time the observation of stimulated emissions from the gas–liquid interface between two adjacent bubbles in highly ordered foams containing Rhodamine 6 G and surfactant. Stimulated emissions centred at 595 nm were observed when a monolayer of foam (～liquid fraction 0.11), placed on a highly reflective surface, was pumped with a 532 nm continuous wave laser directed along ～45° from the direction perpendicular to the substrate. Additionally, using confocal microscopy and micro-photoluminescence, it was found that the liquid fraction of the foam, the gap between two adjacent bubbles and the incidence angle of the laser are important parameters in guiding the light and promoting stimulated emissions at the interface. The adsorption of the polymer and dye increased the local concentration at the narrowest gaps between pairs of bubbles, which led to the formation of hemispherical micelles-dye agglomerates. The presence of the micelles aggregation caused random scattering induced stimulated emission. These results could have a significant impact on a number of applications, such as photocatalytic conversion at bubble interfaces, where TiO2 can scatter light and hence reaction rates may be increased.
关键词： photocatalysis,Stimulated emission,interface,lasing,microbubbles,foam
更新于2025-09-23 15:22:29
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Robust Wavelength-Converting and Lasing Media from Wafer-Scale Inorganic Perovskites Enabled by a Protective Surface Layer
摘要： Despite that the inorganic halide perovskites show great promise in wavelength-conversion and lasing applications, the stability and scalability remain as the obstruction toward practical applications. Herein, we, for the first time, employ the wafer-scale inorganic perovskite single crystals to address the above issue. Our spectroscopic analysis reveals that the carrier trapping on the crystal surface is the most probable culprit to hinder the optical amplification for the weak-penetrating one-photon pumping, whilst, the interior of the crystal preserves intact and show low-threshold stimulated emission by two-photon absorption in the near infrared regime. Thanks to the effective protection from the surface layer, the stimulated emission maintains 90% of the initial intensity upon uninterrupted pumping of 4 hours and shows nearly constant threshold upon long-term storage without any encapsulation (> one year). By exploiting a parallel-mirror cavity, an optically pumped wavelength-converting and laser device featuring a spatially coherent output beam is constructed. Our finding greatly advances the development of practical coherent light sources based on halide perovskites.
关键词： wavelength-conversion,lasing,scalability,two-photon absorption,inorganic halide perovskites,stability,coherent light sources,stimulated emission
更新于2025-09-23 15:21:01
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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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Single Molecule Nonlinearity in a Plasmonic Waveguide
摘要： Plasmonic waveguides offer the unique possibility to confine light far below the diffraction limit. Past room temperature experiments focused on efficient generation of single waveguide plasmons by a quantum emitter. However, only the simultaneous interaction of the emitter with multiple plasmonic fields would lead to functionality in a plasmonic circuit. Here, we demonstrate the nonlinear optical interaction of a single molecule and propagating plasmons. An individual terrylene diimide (TDI) molecule is placed in the nanogap between two single-crystalline silver nanowires. A visible wavelength pump pulse and a red-shifted depletion pulse travel along the waveguide, leading to stimulated emission depletion (STED) in the observed fluorescence. The efficiency increases by up to a factor of 50 compared to far-field excitation. Our study thus demonstrates remote nonlinear four-wave mixing at a single molecule with propagating plasmons. It paves the way toward functional quantum plasmonic circuits and improved nonlinear single-molecule spectroscopy.
关键词： quantum emitter,nonlinear optics,stimulated emission depletion STED,two-wire transmission line,single-crystalline silver flake,plasmonic nanocircuit
更新于2025-09-23 15:19:57
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Amplified Expansion Stimulated Emission Depletion Microscopy
摘要： Expansion microscopy (ExM) enhances spatial resolution using a swellable polymer that expands the sample volume by a factor of ~4 in one dimension and factor of ~20 in volume. Combining ExM with stimulated emission depletion (STED) microscopy, referred to as ExSTED, increases the resolution to up to 10 nm. However, photobleaching is a critical issue in ExSTED because sample expansion lowers fluorophore density and high-resolution STED requires high depletion intensity. To overcome these issues, we developed highly bright expansion nanoscopy using biotin-avidin signal amplification to increase the labeling density. Our method provides up to a 7-fold increase in fluorescence signal intensity in expanded samples, thus enabling the use of STED imaging with the maximum depletion intensity of a commercial microscope in the order of GW/cm2. We demonstrate the method using biotinylated antibodies and genetic incorporation approaches of biotin to a specific molecule or organelle.
关键词： stimulated emission depletion microscopy,super-resolution microscopy,expansion microscopy
更新于2025-09-19 17:15:36
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Optical Fiber Communications (Principles and Applications) || Optical Sources and Transmitters
摘要： An optical source provides the electrical–optical signal conversion efficiently that enables the optical output to be effectively coupled and launched into the optical fiber. It is an active device that requires external power supply for operation in optical fiber communications. This chapter begins with the major requirements or desirable properties for the optical source in general. Light emitting diodes (LEDs) and injection laser diodes (ILDs) {which are simply known as laser diodes (LDs)} are the most popular semiconductor optical sources. LED is an incoherent optical source. It can support many propagation modes of light within its structure. This is the reason why is it employed as a multimode optical source. Whereas, ILD is a highly coherent optical source that has a very narrow spectrum and fast response time. Thus, it is mostly used as a single-mode optical source in single-mode propagation requirements. In this chapter the basic principle of operation of both these optical sources along with their major structures and configurations are described. For producing the light signal, the emission can be a spontaneous emission, as in the case of LED, or a stimulated emission as in the case of ILD. The spontaneous emission takes place when electrons are brought to a very high energy level, and an unstable state. The electrons will return spontaneously (within few picoseconds) to a stable state, and will consequently emit photons.. The optical wavelength is determined by the amount of energy the electron releases. A laser diode operates with stimulated emission in which the electrons enters and stays in a high-energy state for a few microseconds. Then it changes its state spontaneously. During this state, the photon stimulates so as to emit the energy in the form of another photon. Thus, the laser produces the light signal. Finally, a typical functional block schematic including features and operations of optical transmitter is covered to assess the utility of optical sources.
关键词： LED,spontaneous emission,optical transmitter,optical sources,stimulated emission,laser diode,optical fiber communications
更新于2025-09-12 10:27:22
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Physics, Pharmacology and Physiology for Anaesthetists (Key Concepts for the FRCA) || Laser principles
摘要： Lasers are used in many types of surgery and the examinations will test both your understanding of their underlying principles and aspects related to laser safety. LASER is an acronym that stands for Light Amplification by Stimulated Emission of Radiation. The definition of the word laser also gives a very succinct description of its mode of action. A lasing medium describes the type of laser, for example a ‘CO2’ laser contains CO2 as the lasing medium. The medium is pulsed with energy from an external source, typically an intense light or electrical discharge. The application of external energy raises the electrons in the lasing medium to a higher orbit or energy state around their host atom. When the pulsed external energy is off, the excited electrons return to a lower energy orbit and, in doing so, release photons (light). The wavelength of this light is dependent upon the nature of the lasing medium and the energy difference between the high energy and low energy orbits. Photons travel in random directions although some will travel parallel to the walls of the container that holds the lasing medium. This container has mirrors at both ends that reflect the photons back and forth through the medium. As each photon hits an electron in the excited state it stimulates it to release its own photon and, in doing so, to return to a lower energy orbit. The phenomenon of this stimulated release of photons is that they share the same wavelength and phase as the photon causing the release. The mirror at one end of the container is partially mirrored in that it reflects a proportion of the photons that hit it but also allows a proportion of them out of the container as laser light. Three important properties of laser light produced by this process are that it is monochromatic, collimated and coherent.
关键词： coherent,Laser,monochromatic,Light Amplification by Stimulated Emission of Radiation,collimated
更新于2025-09-12 10:27:22
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - The Laser Linewidth – Fairy Tales and Physical Evidence
摘要： The laser linewidth manifests the spectral coherence of a lasing resonator mode. It is of fundamental importance, theoretically as much as practically. For more than half a century we have been told that the laser linewidth is a result of quantum fluctuations due to spontaneous emission, which induce amplitude and phase fluctuations, whereas stimulated emission occurs in phase with the incident field. Unfortunately, in such a scenario each emission process would violate the law of energy conservation. We show that a (spontaneous or stimulated) emission process occurs 90 degrees in lead of the incident field, converts one atomic excitation into one photon in the lasing mode and, therefore, conserves the energy, whereas the mentioned fluctuations are the result of vacuum energy and occur at an orders-of-magnitude faster time scale than an emission process.
关键词： spontaneous emission,stimulated emission,resonator,laser,spectral coherence
更新于2025-09-11 14:15:04
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Colour Reproduction in Electronic Imaging Systems (Photography, Television, Cinematography) || Light Amplification in Lasers
摘要： In physics, specifically statistical mechanics, a population inversion occurs when a system (such as a group of atoms or molecules) exists in a state with more members in an excited state than in lower energy states. The concept is of fundamental importance in laser science because the production of a population inversion is a necessary step in the workings of a standard laser.
关键词： Boltzmann distribution,stimulated emission,population inversion,statistical mechanics,laser
更新于2025-09-11 14:15:04
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in light filaments
摘要： We present our results on the emissions from N2+ pumped with ultrafast filaments using high-resolution pump probe. Our result shows the phase relation between transition lines at earlier delays. We show that the gain on transition lines extends beyond the time when coherence is lost.
关键词： stimulated emission,N2+,rotational wave packet,light filaments,ultrafast pump probe
更新于2025-09-09 09:28:46