Optical diagnostics are essential in monitoring the progression of plasma in high-energy-density physics research. The abrupt transitions in plasma evolution, whether caused by laser irradiation or hydrodynamic instabilities, cannot be accurately distinguished using only two-dimensional (2D) gated detectors or a streak camera individually. In this paper, we introduce a hybrid diagnostic system that combines a streak camera and gated detectors. This innovative approach enables us to measure both the plasma density evolution and 2D morphology simultaneously. These advanced diagnostics have been utilized in recent laboratory astrophysics experiments, effectively capturing the plasma flow density distribution and flow velocity.

This study investigated direct fluorescence generation from a nematic liquid crystal (NLC) NJU-LDn-4 under femtosecond laser excitation. The absorption, transmittance, excitation, and emission spectra of the NLC were assessed. The relationship between the femtosecond pump power and fluorescence intensity was analyzed, revealing a quadratic increase and indicating that two-photon absorption (2PA) is the primary fluorescence mechanism. The LC microstructure was designed using photoalignment technology, allowing the generated fluorescence to reflect the corresponding structure. This research can establish a foundation for tunable LC microstructured fluorescence, with potential applications in fluorescence microscopy and optoelectronics.

Black silicon materials prepared via microstructuring and hyperdoping by ultrafast laser irradiation have attracted immense attention owing to their high absorption and photon sensitivity across a broadband spectral range. However, a conflict exists between the repair requirements for the high amount of laser-induced damage and the thermally unstable hyperdoped impurities, resulting in low photon sensitivity and rapid decay at subbandgap wavelengths for the annealed black silicon. In this work, the properties of titanium (Ti) hyperdoped silicon have been explored using first-principle calculations. The findings of the study reveal that the interstitial Ti atoms exhibit a deep impurity band and low formation energy in silicon, which may be responsible for the stable subbandgap absorption that is achieved. Furthermore, femtosecond laser irradiation and rapid thermal annealing have been applied to manufacture Ti-hyperdoped black silicon (b-Si:Ti). The b-Si:Ti compound prepared by hyperdoping displayed high absorption across the visible and infrared ranges, with absorptance exceeding 90% for visible lights and 60% for subbandgap wavelengths. Additionally, the subbandgap absorption remains high even after intense thermal annealing, indicating a stable deep-level impurity of Ti in silicon. The experimental findings are consistent with the simulation results and complement each other to reveal the physical mechanisms responsible for the high performance of b-Si:Ti. The results thus demonstrate promising prospects for the application of black silicon in high-efficiency solar cells, photoelectric imaging, and flip-chip interconnection systems.

This study entailed the development of a high-gradient modulation of microbunching for traditional radiation frequency accelerators using a minimized system driven by a relativistic Laguerre–Gaussian (LG) laser in three-dimensional particle-in-cell (PIC) simulations. It was observed that the LG laser could compress the transverse dimension of the beam to within a 0.7 µm radius (divergence≈4.3 mrad), which is considerably lower than the case tuned by a Gaussian laser. In addition, the electron beam could be efficiently modulated to a high degree of bunching effect (>0.5) within ∼21 fs (∼7 μm) in the longitudinal direction. Such a high-gradient density modulation driven by an LG laser for pre-bunched, low-divergence, and stable electron beams provides a potential technology for the system minimization of X-ray free-electron lasers (XFELs) and ultrashort-scale (attosecond) electron diffraction research.

In the scheme of fast ignition of inertial confinement fusion, the fuel temperature mainly relies on fast electrons, which act as an energy carrier, transferring the laser energy to the fuel. Both conversion efficiency from the laser to the fast electron and the energy spectrum of the fast electron are essentially important to achieve highly effective heating. In this study, a two-dimensional particle in cell simulation is applied to study the generation of fast electrons from solid-density plasmas with different laser waveforms. The results have shown that the slope of the rising edge has a significant effect on fast electron generation and energy absorption. For the negative skew pulse with a relatively slow rising edge, the J×B mechanism can most effectively accelerate the electrons. The overall absorption efficiency of the laser energy is optimized, and the fast electron yield in the middle- and low-energy range is also improved.

The plasma mirror system was installed on the 1 PW laser beamline of Shanghai Superintense Ultrafast Laser Facility (SULF) for enhancing the temporal contrast of the laser pulse. About 2 orders of magnitude improvement on pulse contrast was measured on picosecond and nanosecond time scales. The experiments show that high-contrast laser pulses can significantly improve the cutoff energy and quantity of proton beams. Then different target distributions are assumed in particles in cell simulations, which can qualitatively assume the expansion of nanometer-scale foil. The high-contrast laser enables the SULF-1PW beamline to generally be of benefit for many potential applications.

We demonstrated a scheme to differentiate the high-harmonic generation (HHG) originating from the surface states and bulk states of the topological insulator Bi2Se3. By adopting two-color mid-infrared laser fields on Bi2Se3, we found that the nonlinear response sensitively depends on the relative phase of the driving fields. The even harmonics arise from the surface states with a clear signature, whose modulation period equals the cycle of the second-harmonic generation (SHG) field. We reveal that the weak SHG perturbs the nontrivial dipole phase of the electron-hole pair in surface states, and thus leads to the modulation of HHG. It provides a means to manipulate the ultrafast dynamics in surface states through adopting a weak perturbing laser field.

Optical line tweezers have been an efficient tool for the manipulation of large micron particles. In this paper, we propose to create line traps with transformable configurations by using the transverse electromagnetic mode-like laser source. We designed an optical path to simulate the generation of the astigmatic beams and line traps with a series of lenses to realize the rotational transformation with respect to the rotation angle of cylindrical lenses. It is shown that the spherical particles with diameters ranging from 5 μm to 20 μm could be trapped, aligned, and revolved in experiment. The periodical trapping forces generated by transformable line traps might open an alternative way to investigate the mechanical properties of soft particles and biological cells.

“Lotus effect” glass surfaces with fluorinated ethylene propylene were successfully fabricated by using a femtosecond laser-induced backward transfer (LIBT) method. By space-selectively modifying both the surface morphology and surface chemistry in a single step, LIBT provides a convenient and flexible route to fabricate superhydrophobic surfaces with ultralow adhesion. A systematic mechanism responsible for the anisotropic wetting behaviors and adhesion modulation was proposed with a combination of the Cassie and Wenzel models. X-ray photoelectron spectroscopy revealed that oxidation and defluorination were induced by laser radiation. LIBT is proved to be a promising method for programmable manipulations of functional surfaces with diverse wettability.

Infrared (IR) thermal imaging has aroused great interest due to its wide application in medical, scientific, and military fields. Most reported approaches for regulating thermal radiation are aimed to realize IR camouflage and are not applicable to enhance thermal imaging. Here, we introduce a simple and effective method to process porous glass by femtosecond laser scanning, where distributed nanocavities and nanowires were produced, which caused improvement of the treated glass emissivity. The as-prepared sample possessed better IR thermal radiation performance but lower transmittance to visible light. We also demonstrated its applicability by placing it in different backgrounds, where the IR image temperature of laser-treated glass was closer to the actual environment, and this strategy may provide a new vision for enhanced thermal imaging.

A ring-shaped focus, such as a focused vortex beam, has played an important role in microfabrication and optical tweezers. The shape and diameter of the ring-shaped focus can be easily adjusted by the topological charge of the vortex. However, the flow energy is also related to the topological charge, making the individual control of diameter and flow energy of the vortex beam impossible. Meanwhile, the shape of the focus of the vortex beam remains in the hollow ring. Expanding the shape of focus of structural light broadens the applications of the vortex beam in the field of microfabrication. Here, we proposed a ring-shaped focus with controllable gaps by multiplexing the vortex beam and annular beam. The multiplexed beam has several advantages, such as the diameter and flow energy of the focal point can be individually controlled and are not affected by the zero-order beam, and the gap size and position are controllable.

Ince–Gaussian (IG) beams, as eigenfunctions of the paraxial wave equation in elliptical coordinates, are attracting increasing interest owing to their propagation-invariant and full-field properties. Optical amplification via parametric interactions can further expand their application areas, yet it is rarely studied. In this work, we report on a high-fidelity parametric amplifier for IG beams. The nonlinear transformation of the spatial spectra of the signal and associated influences on the beam profiles of the amplified signal, under different pump structures, were theoretically and experimentally investigated. By using a perfect flattop beam as the pump, we show that the transverse structure of IG signals is well maintained, and the distortion induced by radial-mode degeneration is overcome during amplification. This proof-of-principle demonstration paves the way for a mode-independent and distortion-free amplifier of arbitrary structured light and has great significance in relevant areas, such as quantum optics, tunable infrared-laser generation, and image amplification.

In this paper, an effective method is proposed to generate specific periodical surface structures. A 532 nm linearly polarized laser is used to irradiate the silicon with pulse duration of 10 ns and repetition frequency of 10 Hz. Laser-induced periodic surface structures (LIPSSs) are observed when the fluence is 121 mJ/cm2 and the number of pulses is 1000. The threshold of fluence for generating LIPSS gradually increases with the decrease of the number of pulses. In addition, the laser incident angle has a notable effect on the period of LIPSS, which varies from 430 nm to 1578 nm, as the incident angle ranges from 10° to 60° correspondingly. Besides, the reflectivity is reduced significantly on silicon with LIPSS.

Optical levitation technology is a new levitation technology for trapping micro/nano-particles. By taking advantage of the mechanical effect of light, it has the characteristics of non-contact and high sensitivity. However, the traditional optical levitation system is large in volume, complex in adjustment, and greatly affected by the external environment. Herein, a miniature optical levitation system based on a laser diode, miniature lenses, and a micro-electro-mechanical system (MEMS) particles cavity is proposed. First, we analyze the output spot characteristics of the laser diode. Being compared the characteristics of different kinds of laser diodes, the type, wavelength, and power of diodes in the levitation system are determined. Then, the micro-particles cavity is fabricated based on the MEMS process. The MEMS process is widely used in the manufacturing of micro-electronic devices because of its advantages of small size, high precision, and easy mass production. The particle cavity processed in this way can not only ensure the advantage of small volume, but also possesses high processing repeatability. The volume of the entire package including the light source, focusing lenses, and MEMS cavity is just Φ 10 mm×33 mm, which is the smallest optical levitation system reported, to the best of our knowledge. After the entire levitation system is designed and set up, one silica particle of 10 µm diameter is stably trapped in the atmospheric environment. Finally, the micro-displacement and vibration signal are detected by a four-quadrant photoelectric detector to evaluate the stiffness of the optical levitation system.

In this work, we used femtosecond laser double-pulse trains to produce laser-induced periodic surface structures (LIPSS) on 304 stainless steel. Surprisingly, a novel type of periodic structure was discovered, which, to the best of our knowledge, is the first in literature. We surmised that the cause for this novel LIPSS was related to the weak energy coupling of subpulses when the intrapulse delay was longer than the thermal relaxation time of stainless steel. Furthermore, we found that the fluence combination and arrival sequence of subpulses in a double-pulse train also influenced LIPSS morphology.

We present the perfect light absorption of monolayer molybdenum disulfide (MoS2) in a dielectric multilayer system with two different Bragg mirrors. The results show that the strong absorption of visible light in monolayer MoS2 is attributed to the formation of optical Tamm states (OTSs) between two Bragg mirrors. The MoS2 absorption spectrum is dependent on the layer thickness of Bragg mirrors, incident angle of light, and the period numbers of Bragg mirrors. Especially, the nearly perfect light absorption (99.4%) of monolayer MoS2 can be achieved by choosing proper period numbers, which is well analyzed by the temporal coupled-mode theory.

Suppression of stress and crack generation during picosecond laser processing in transparent brittle materials such as glass was successfully demonstrated by a picosecond laser pulse with temporal energy modulation. The origin of deterioration in processing accuracy could be interpreted in terms of the discontinuous movement of plasma in the vicinity of the focus. To reveal the effectiveness of the temporal energy modulation for smooth machining, such plasma motion was simulated by the finite-difference time-domain method. Furthermore, photoinduced birefringence was observed using a high-speed polarization camera.