- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Mode-locked All-fiber Laser Emitting Two-color High-order Transverse Mode
摘要： We demonstrate that the mode-locked all-?ber laser can simultaneously emit two-color broadband LP11 transverse mode in the near-infrared region by sharing a common mode-selective coupler (MSC). The MSC mode converter is designed to achieve simultaneous dual-channel mode conversion corresponding to the wavelength regions at 1.0 (cid:22)m and 1.5 (cid:22)m, in which each channel possesses broadband mode conversion from LP01 to LP11 mode with high mode purity. As a proof of concept, we implement an all-?ber ytterbium (Yb) and erbium (Er) doped ?ber lasers with mode-locked two-color LP11 modal output. The laser consists of two ring cavities combined with a common MSC mode converter. The generated LP11 modal pulses have a full width at half maximum (FWHM) of 11 nm and 8.1 nm for Yb- and Er-doped ?ber laser (YDFL and EDFL), respectively. The presented ?ber laser would represent a promising light source in the ?eld of structured light and ultrafast optics.
关键词： Two-color,mode-locking,MSC,dual-channel mode conversion
更新于2025-11-28 14:24:03
-
Enhancement of THz Generation by Two-Color TW Laser Pulses in a Low-Pressure Gas
摘要： We identify experimental conditions for efficient generation of THz pulses by high power near IR laser radiation: 2 TW, 30 fs, 800-nm laser pulses with their second harmonic were slightly focused in a low-pressure gas cell in such a way to avoid multiple filamentation and excessive ionization. This two-color scheme yields a microjoule level of THz pulses which is two orders of magnitude higher than the signal generated in the atmosphere of ambient air.
关键词： THz,Two-color,Plasma absorption,Terawatt,Chirp,Filament,Low pressure,Saturation
更新于2025-09-23 15:21:01
-
Ellipticity control of high-order harmonic generation with nearly orthogonal two-color laser fields
摘要： Elliptically polarized high-order harmonics opens a path toward the study of ultrafast dynamics in circular dichroism of magnetic materials, chiral molecules, and electronic spin motion. Recently, efficient high-order harmonic generation with controllable ellipticity has attracted considerable attention in experiment and theory. Here, we experimentally demonstrate a scenario using cross-linearly-polarized two-color fields consisting of a fundamental field and its second harmonic (SH). Through adjusting the relative phase, crossing angle, and intensity ratio of the cross-linearly-polarized two-color field, we obtain ellipticity-tunable high-order harmonics, with ellipticity up to ε = 0.73. Meanwhile, the elliptically polarized high-order harmonics preserve high efficiency. Furthermore, when the intensity of the SH field is stronger than that of the fundamental field, the even order harmonics will become several times stronger than the odd order harmonics with opposite helicity.
关键词： attosecond science,high-order harmonic generation,ellipticity control,strong-field physics,two-color laser fields
更新于2025-09-23 15:21:01
-
Intense circularly polarized attosecond pulse generation from solid targets irradiated with a two-color linearly polarized laser
摘要： A method for the production of intense circularly polarized (CP) attosecond pulses from relativistic laser-solid interactions is proposed, where a two-color linearly polarized (LP) laser is used. The polarization, photon frequency, and other properties of the obtained attosecond pulse can be controlled by adjusting the ratio of the dichromatic driving LP field in different harmonics, which is much easier and more efficient than those previously using CP driving lasers. Both one- and two-dimensional particle-in-cell simulations show that a CP attosecond extreme-ultraviolet pulse with an intensity of 1.4 × 1019 W/cm2 and a duration of about 120 as is obtained by a two-color LP laser at intensities in the fundamental and second harmonics of, respectively, 1.5 × 1022 and 6.4 × 1021 W/cm2, which can be applied for the detection of the magnetic and chiral properties of materials.
关键词： relativistic laser-solid interactions,attosecond pulse,two-color linearly polarized laser,circularly polarized,extreme-ultraviolet pulse
更新于2025-09-23 15:21:01
-
Analysis of two-color laser-induced electron emission from a biased metal surface using an exact quantum mechanical solution
摘要： Photoelectron emission from solids, as driven by high-intensity lasers, offers a platform for the coherent control of electron motion on ultrashort spatiotemporal scales. By solving the time-dependent Schr?dinger equation, we present an exact analytical solution for the nonlinear ultrafast electron emission from a dc-biased metal surface illuminated by two-color laser fields. We systematically examine the combined effects of a dc electric field and two-color laser fields. In addition to the remarkable tunability of electron emission processes due to interference from two-color laser fields, we find that a strong dc electric field not only opens up more tunneling emission channels, but also introduces intense modulation to the emission current. We find surprising results that strong current modulation (with respect to the phase difference of the two-color lasers) persists (>70%), even with a large dc bias (i.e., ratio of the electric fields for dc : fundamental laser : second-harmonic laser ～= 1 : 0.5 : 0.07). In the meantime, the average emission current level increases by about three orders of magnitude relative to the case of zero dc bias. Application of our model to time-resolved photoelectron spectroscopy is exemplified and shows that the dynamics of the n-photon excited states depends strongly on the applied dc field. Our study suggests a practical way to maintain a strong modulation to high current photoemission, by the addition of a large dc bias for two-color laser-induced electron emission.
关键词： dc electric field,two-color laser fields,ultrafast electron emission,photoelectron emission,time-dependent Schr?dinger equation
更新于2025-09-23 15:19:57
-
Giant Isolated Attosecond Pulses from Two-Color Laser-Plasma Interactions
摘要： A new regime in the interaction of a two-color (ω; 2ω) laser with a nanometer-scale foil is identified, resulting in the emission of extremely intense, isolated attosecond pulses—even in the case of multicycle lasers. For foils irradiated by lasers exceeding the blow-out field strength (i.e., capable of fully separating electrons from the ion background), the addition of a second harmonic field results in the stabilization of the foil up to the blow-out intensity. This is then followed by a sharp transition to transparency that essentially occurs in a single optical cycle. During the transition cycle, a dense, nanometer-scale electron bunch is accelerated to relativistic velocities and emits a single, strong attosecond pulse with a peak intensity approaching that of the laser field.
关键词： two-color laser,laser-plasma interactions,attosecond pulses,coherent synchrotron emission
更新于2025-09-23 15:19:57
-
Characterization of tracers for two-color laser-induced fluorescence liquid-phase temperature imaging in sprays
摘要： The variation of the fluorescence spectral signature of tracer solutions with temperature enables temperature imaging measurements in liquids and sprays by simultaneously recording and rationing the fluorescence intensity detected in two separate wavelength channels. In this work, we recorded fluorescence spectra of ethanol-based solutions of nine laser dyes used as tracers (PTP, stilbene 1, coumarin 152, coumarin 153, rhodamine B, rhodamine 101, pyrromethene 597, DCM, and pyridine 1) after excitation at either 266, 355, or 532 nm (depending on the dye) for temperatures between 298 and 348 K (close to the boiling point of the solvent), and for concentrations (depending on dye) around 10 mg/l (i.e., ~ 10–5 mol/l). The influence of signal self-absorption was investigated for the tracers best suited for thermometry, rhodamine B and coumarin 152, where the latter is almost unaffected due to its large Stokes shift. In thin-film (100 μm) cells, possible concentration effects on the fluorescence spectrum were investigated in the absence of signal self-absorption in the 0.1–10 and 0.5–50 mg/l range for rhodamine B and coumarin 152, respectively. Sensitivities of the two-color intensity ratios were determined for two selected color detection channels for each tracer characterized by their center wavelength and spectral half width and conditioned on averaged intensities of larger than 10% of the spectral peak of their respective fluorescence spectrum. The use of coumarin 152 that showed the overall best spectroscopic properties was demonstrated for temperature imaging in a burning ethanol spray.
关键词： coumarin 152,rhodamine B,sprays,temperature imaging,two-color laser-induced fluorescence,tracers
更新于2025-09-23 15:19:57
-
Infrared + vacuum ultraviolet two-color ionization spectroscopy of neutral metal complexes based on a tunable vacuum ultraviolet free-electron laser
摘要： This paper describes an experimental technique for studying neutral metal complexes using infrared + vacuum ultraviolet (IR+VUV) two-color ionization spectroscopy based on a tunable VUV free-electron laser (VUV-FEL). The preliminary IR spectroscopy results of mass-selected nickel tetracarbonyl are reported in this work. The results demonstrate that the tunable VUV-FEL light allows the selective ionization of a given neutral cluster free of confinement along with the recording of well-resolved IR spectra. As the ionization energies of many neutral clusters are accessible by a broadly tunable VUV-FEL (50–150 nm) and near-threshold ionization can be readily achieved, the proposed experimental method offers unique possibilities for the size-specific study of a wide variety of confinement-free neutral clusters.
关键词： infrared,vacuum ultraviolet,tunable VUV free-electron laser,two-color ionization spectroscopy,neutral metal complexes
更新于2025-09-23 15:19:57
-
Selection of the magnetic quantum number in resonant ionization of neon using an XUV-IR two-color laser field
摘要： A recent experiment [Villeneuve et al. Science 356, 1150 (2017)] has shown that two-color photoionization of neon by the combination of an attosecond XUV pulse train and a moderately strong, linearly polarized IR pulse can preferentially produce photoelectrons with orbital angular quantum number l = 3 (f-wave) and magnetic quantum number m = 0. This result was rationalized by the occurrence of different Stark shifts of m = 0 and |m| = 1 sub-levels in the IR laser field. Here we perform 3D time-dependent Schrodinger equation calculations with a neon effective potential to identify the mechanism for the selective excitation and ionization of m = 0 sub-levels. Calculations of the ionization and excitation yields as a function of the IR intensity and the XUV and IR photon energy reveal that a coupling between two dominant ionization channels involving 3p and 3d intermediate excitations is responsible for the observed m-level selectivity. We compare calculated and measured photoelectron velocity map images and ionization yields over a range of IR intensities and XUV and IR photon energies, and confirm that the m = 0 or |m| = 1 channel, and thus a single set of the quantum numbers, (Jion, l, m), can be selected by an appropriate choice of these parameters.
关键词： photoelectron velocity map images,XUV-IR laser field,neon,time-dependent Schrodinger equation,two-color photoionization,magnetic quantum number,Stark shifts
更新于2025-09-23 15:19:57
-
Synchronous full-field measurement of temperature and deformation based on separated radiation and reflected light
摘要： Optical method has been playing an important role in measuring temperature and deformation at elevated temperatures. Here we propose a simple and effective iterative algorithm to realize accurate and simultaneous measurement of the full-field temperature and deformation of specimens subjected to flame heating at temperatures up to 1000 °C. The algorithm separates the optical images of specimen surface into radiant and reflected parts. The radiant part is used to calculate the full-field temperature by an improved two-color method, and the reflected part is used to obtain the deformation of the specimen surface based on high-temperature digital image correlation method. Experimental validation shows that the proposed method can effectively eliminate the mutual interference between the radiation and reflected light, displaying great potential for synchronous measurement of temperature and deformation with sufficient accuracy by using one camera.
关键词： Two-color method,Synchronous temperature and deformation measurement,Iterative algorithm,Separation of radiation and reflected light
更新于2025-09-19 17:15:36