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Radiation reaction in electrona??beam interactions with high-intensity lasers
摘要： Charged particles accelerated by electromagnetic fields emit radiation, which must, by the conservation of momentum, exert a recoil on the emitting particle. The force of this recoil, known as radiation reaction, strongly affects the dynamics of ultrarelativistic electrons in intense electromagnetic fields. Such environments are found astrophysically, e.g. in neutron star magnetospheres, and will be created in laser–matter experiments in the next generation of high-intensity laser facilities. In many of these scenarios, the energy of an individual photon of the radiation can be comparable to the energy of the emitting particle, which necessitates modelling not only of radiation reaction, but quantum radiation reaction. The worldwide development of multi-petawatt laser systems in large-scale facilities, and the expectation that they will create focussed electromagnetic fields with unprecedented intensities > 1023 Wcm?2, has motivated renewed interest in these effects. In this paper I review theoretical and experimental progress towards understanding radiation reaction, and quantum effects on the same, in high-intensity laser fields that are probed with ultrarelativistic electron beams. In particular, we will discuss how analytical and numerical methods give insight into new kinds of radiation–reaction-induced dynamics, as well as how the same physics can be explored in experiments at currently existing laser facilities.
关键词： Laser-wakefield acceleration,Radiation reaction,Synchrotron radiation,Particle-in-cell simulations,Strong-field QED,High-power lasers
更新于2025-09-23 15:21:01
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Nanocomposites for Photonic and Electronic Applications || Nanocomposite-based random lasers
摘要： First demonstrated in 1960 [1], the laser, as we know today, essentially consists of a pump source, a gain medium, and a cavity composed by a set of mirrors. The role of the cavity is to provide optical feedback, besides determining the directionality and modes of the laser [2]. A few years after the laser invention, V. S. Letokhov proposed in 1967 that coherent oscillation could be generated without the need for the mirror cavity [3], and the optical feedback would be provided by a scattering medium. Several years later, two publications described experimental results of stimulated emission in powders employing rare-earth materials of micron size [4,5]. However, the real breakthrough in the so-called random laser (RL) emission came in 1994 [6], when Lawandy and coworkers employed a nanocomposite prepared from a colloidal suspension of organic dye and nanometer-size TiO2 to clearly demonstrate laser emission in a gain medium in the presence of scatters. In the same year, Sha and coworkers studied the temporal emission of a similar nanocomposite RL with picosecond resolution, thus corroborating the laser action [7].
关键词： optical feedback,photonic devices,random lasers,nanocomposites,plasmonics
更新于2025-09-23 15:21:01
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Equine Surgery || Lasers in Veterinary Surgery
摘要： Surgical lasers facilitate minimally invasive surgery, allow surgical access to otherwise inaccessible areas, and induce tissue interactions, which cannot be obtained with conventional surgical instrumentation. Surgical laser procedures can be performed on an outpatient basis and have eliminated procedures that previously required general anesthesia and hospitalization. Surgeons should be knowledgeable about which procedures can be accomplished with surgical lasers and which are better suited to conventional surgery. This chapter will provide information and guidelines on the use of surgical lasers in equine surgery.
关键词： equine surgery,minimally invasive surgery,carbon dioxide laser,Surgical lasers,neodymium:yttrium-aluminum-garnet laser,holmium:yttrium-aluminum-garnet laser,diode laser
更新于2025-09-23 15:21:01
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Non-Fourier Estimate of Electron Temperature in Case of Femtosecond Laser Pulses Interaction with Metals
摘要： This work is devoted to the electron temperature variation in metals through interaction with femtosecond laser pulses. Our study was inspired by the last mathematical breakthroughs regarding the exact analytical solutions of the heat equation in the case of flash laser-matter interaction. To this purpose, the classical Anisimov’s two temperature model was extended via the 3D telegraph Zhukovsky equation. Based upon this new approach, the computational plots of electron thermal fields during the first laser pulse interaction with a gold surface were inferred. It is shown that relaxation times and coupling factors over electron thermal conductivities (g/K) govern the interaction between the laser pulse and metal sample during the first picoseconds. The lower the factor g/K, the higher the electron temperature becomes. In contrast, the lower the relaxation time, the lower the electron temperature.
关键词： two temperature model,3D telegraph equation,femtosecond lasers-metal interaction,metals
更新于2025-09-23 15:21:01
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TiOxNy Thin Film Sputtered on a Fiber Ball Lens as Saturable Absorber for Passive Q-Switched Generation of a Single-Tunable/Dual-Wavelength Er-Yb Double Clad Fiber Laser
摘要： The use of titanium oxynitride (TiOxNy) thin ?lms as a saturable absorber (SA) element for generation of passive Q-switched (PQS) laser pulses, from a linear cavity Er-Yb double-clad ?ber (EYDCF) laser, is demonstrated. Additionally, the deposition of the material as a thin ?lm covering a ?ber micro-ball lens (MBL) structure is reported for the ?rst time. The TiOxNy coating is deposited by a direct current (DC) magnetron-sputtering technique. The MBL is inserted within the laser cavity in a re?ection con?guration, alongside a re?ecting mirror. As a result, the coated ?ber MBL simultaneously acts as a SA element for PQS laser pulses generation and as an interference ?lter for wavelength selection and tuning of the generated laser line. Tunable single-laser emission in a wavelength range limited by dual-wavelength laser generation at 1541.96 and 1547.04 nm is obtained. PQS laser pulses with a repetition rate from 18.67 to 124.04 kHz, minimum pulse duration of 3.57 μs, maximum peak power of 0.359 W, and pulse energy of 1.28 μJ were obtained in a pump power range from 1 to 1.712 W.
关键词： Q-switched ?ber lasers,titanium oxynitride,DC magnetron sputtering,?ber micro-ball lens,saturable absorber materials
更新于2025-09-23 15:21:01
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Green Higha??Power Disk Lasers and Industrial Applications
摘要： In the publicly-funded ProLasKu project, the laser manufacturer Trumpf has developed a high-power laser with a wavelength of 515 nm. Substantial progress in the industrial applications of green lasers has been achieved in a cooperation between the Technical University of Munich and the companies Siemens and Continental. In addition, a camera-based system for process monitoring and quality assurance in real-time based on image processing methods has been developed.
关键词： green high-power disk lasers,industrial applications,copper,laser beam welding,process efficiency
更新于2025-09-23 15:21:01
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WDM-based bidirectional chaotic communication for semiconductor lasers system with time delay concealment
摘要： In this paper, we propose a wavelength-division-multiplexing (WDM)-based chaos communication configuration allowing for the bidirectional exchange of information. In the scheme, the output of a master semiconductor laser (MSL), is injected into slave semiconductor lasers (SSLs), drives the chaotic synchronization of SSLs with optical feedback and electro-optical phase feedback. By calculating the largest Lyapunov exponent (LLE), Lempel–Ziv complexity (LZC) and permutation entropy (PE), we find that the system can generate the chaotic signal with high complexity. We also demonstrate that the chaotic signal bandwidth obtained is as high as 24.68 GHz by selecting the suitable parameters; this configuration intrinsically conceals the electro-optical phase feedback time delay signature (TDS) and optical feedback TDS in transmitted variable; this delayed chaotic dynamics are identically synchronized when the parameters of emitter are exactly matched with that of receiver; while the external and internal parameters’ mismatch between emitter and receiver can lead to the decrease of the synchronization quality. In addition, the result reveals that the channel spacing has influence on cross-correlation coefficient (XCF) quantifying synchronization quality. At last, the messages introduced at two ends of the link can be successfully encrypted and decrypted, and we quantitatively analyze the corresponding Q-factor at different transmission rates.
关键词： Semiconductor lasers,Optical chaos,Time delay signature concealment,All-optical network,bandwidth
更新于2025-09-23 15:21:01
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Hybrid perovskite light emitting diodes under intense electrical excitation
摘要： Hybrid perovskite semiconductors represent a promising platform for color-tunable light emitting diodes (LEDs) and lasers; however, the behavior of these materials under the intense electrical excitation required for electrically-pumped lasing remains unexplored. Here, we investigate methylammonium lead iodide-based perovskite LEDs under short pulsed drive at current densities up to 620 A cm?2. At low current density (J < 10 A cm?2), we ?nd that the external quantum ef?ciency (EQE) depends strongly on the time-averaged history of the pulse train and show that this curiosity is associated with slow ion movement that changes the internal ?eld distribution and trap density in the device. The impact of ions is less pronounced in the high current density regime (J > 10 A cm?2), where EQE roll-off is dominated by a combination of Joule heating and charge imbalance yet shows no evidence of Auger loss, suggesting that operation at kA cm?2 current densities relevant for a laser diode should be within reach.
关键词： ion movement,electrical excitation,lasers,Auger loss,light emitting diodes,Hybrid perovskite semiconductors,Joule heating,external quantum efficiency,charge imbalance
更新于2025-09-23 15:21:01
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[OSA CLEO: Applications and Technology - San Jose, California (2015..-..)] CLEO: 2015 - Photonic generation of linearly-chirped microwave waveform with tunable center frequency and time-bandwidth product
摘要： A novel approach is presented to generate linearly-chirped microwave waveforms with tunable center frequency and expandable time-bandwidth product (TBWP). Different types of waveforms are demonstrated and the maximum measured TBWP is up to ~166.4.
关键词： Radio frequency photonics,Microwaves,Mode-locked lasers
更新于2025-09-23 15:21:01
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Characterization of a Low-Cost, Monolithically Integrated, Tunable 10G Transmitter for Wavelength Agile PONs
摘要： Dynamically reconfigurable passive optical networks (PONs) using time-division multiplexing and dense wavelength division multiplexing will require low-cost, high-performance customer premises equipment to be economically viable. In particular, substantial cost savings can be achieved through the use of efficient re-growth free, foundry-compatible fabrication techniques. Using this strategy, this paper presents the first detailed characterization of a monolithically integrated transmitter comprised of a discretely tunable slotted Fabry–Pérot ridge waveguide laser, an absorptive modulator and a semiconductor optical amplifier (SOA) produced using a standard off-the-shelf AlInGaAs/InP multiple quantum well epitaxial structure. This first generation device demonstrates a discrete single-mode tuning range of approximately 12 nm between 1551nm and 1563 nm with a side-mode suppression ratio ≥30 dB. Moreover, the integrated modulator section is shown to support transmission at 10 Gb/s using non-return to zero on-off keying with an extinction ratio in excess of 8 dB. Furthermore, using a time-resolved chirp measurement technique to examine dynamic deviations in the set carrier frequency, the modulator section exhibits a chirp contribution of <6 GHz using test patterns with high and low frequency content. In addition, the generation of optical bursts through the application of a gating function to the SOA section was found to shift the unmodulated carrier of a typical lasing mode by ≤8 GHz for gating periods comparable with a typical PON burst durations of 125 μs which are faster than the thermal response time of the transmitter material.
关键词： Optical communications,tunable semiconductor lasers,dense wavelength division multiplexing,passive optical networks,time division multiplexing,monolithic integration
更新于2025-09-23 15:21:01