A pulse-dilation framing tube with magnetic lenses was developed， the photocathode biased at -3 000 V was loaded with 10 V/ps oblique pulse. The pulse changed the accelerating voltage between the cathode and the anode， then the additional chromatic aberration which is proportional to the pulse slope was caused. The chromatic aberration characteristics of this tube were analyzed. The simulation results show that the spatial resolution on the axis decreases from about 60 lp/mm to about 2 lp/mm in 20 ps with ignore the time length of the electronic image； otherwise， the duration of the image is included， the spatial resolution on the axis decreases from about 20 lp/mm to about 2 lp/mm in 20 ps. The experimental setup is built according to the simulation， and the experimental results show that the modulation of the 2.5 lp/mm resolution mask declines 10% when the accelerating voltage decreases from -3 000 V to -2 860 V.

The ultrafast pump-probe method is introduced into the optical vortex coronagraph technique， which can realize time-resolved background free imaging of a weak phase object. Specifically， the proposed technique is applied to the diagnostic of air plasma pumped by femtosecond laser pulses. Experimental results show that the formation process of air plasma can be clearly measured. The numerical simulation results are consistent with the experimental results. In addition， two decay processes of the plasma are identified and fitted by double exponential decay. The fast process with a short time scale of 65 ps is attributed to the recombination of electrons and positive ions， while the other relatively slow process with a long time scale of 810 ps is due to the attachment of free electrons to oxygen molecules.

Recently， new photoelectronic materials， magnetic materials and low-dimensional quantum materials， etc， are research frontiers of condensed matter physics. The nanoscale near-field optical dynamics for materials have drawn widely attention due to their rich physics and promising applications. The combination of the ultrahigh temporal resolution of femtosecond laser and the ultrahigh spatial resolution of photoemission electron microscopy is an ultrahigh spatialtemporal-resolved measurement technology， which has injected new vitality to material physics and surface physics and has provided a strong platform. In this review， the ultrahigh spatiotemporal-resolved photoemission electron microscopy is introduced. And the application and progress on the dynamics of surface plasmons， low-dimensional materials and other novel semiconductors， and heterostructure interfaces are discussed. Finally， an outlook in the investigation of surface and interface physics in fs-nm scale are given.

The interaction between light and matter is one of the heart interactions in nature. The complete visualization of this kind of dynamics requires attosecond resolution in time and atomic resolution in space. Ultrashort and coherent electron pulses are central to achieve this goal. This review surveys the important efforts aimed at generation， phase-space control and characterization of ultrashort electron pulses using various optical fields such as microwave， terahertz radiation and visible light， and mainly summarizes its key breakthrough in four-dimensional ultrafast electron microscopy， which opens up the way for the establishment of “attomicroscopy” to allow the imaging of electron motion in the act. Finally， the development prospects of ultrafast electron research is presented.

Table-top attosecond coherent light sources have achieved rapid development in the past two decades. Its research focus has gradually migrated from the generation and characterization of attosecond pulses in early times to tracing and controlling exceedingly fast processes with unprecedented time resolution. Nowadays， attosecond time resolved spectroscopies have been developed to successfully capture transients in simple atomic and molecular systems. Extending their applications to dynamics measurement in complex systems such as chemical molecules， biomolecules and condensed matter is ongoing. This paper reviews the development of ultrafast measuremt techniques using high-order harmonic based attosecond pulses， and introduces their applications in physics， chemistry and information sciences.

As the development of attosecond sources and metrology technologies， the studies on ultrafast electron dynamics in condensed matter have entered the attosecond regime， leading to remarkable progress and breakthroughs in the past 15 years. Novel attosecond metrology has opened up new opportunities for the detection of ultrafast electron movement， resonant excitation， as well as complex electron-electron interactions on the attosecond timescale. This review surveys the important efforts aimed at probing intrinsic attosecond dynamics in condensed matters. The key technologies and status of attosecond sources enabled by high-harmonic generation， attosecond pulse measurements， and the detection of attosecond photoemission time delay on condensed matters are summarized. The development prospects are presented in the end.

Methane hydrate has attracted great attention due to its close relationship with current energy and environmental issues. It is of great significance and application value to carry out fundamental scientific research on the problems related to exploitation of methane hydrate， storage and transportation of natural gas and hydrogen in the form of hydrate. The nucleation process is the key first step of the formation of methane hydrate. It is a microscopic process in which methane and water molecules form clusters and gradually evolve into hydrates. Little is known about how hydrates begin to nucleate and decompose at the molecular level， because of the lack of appropriate experimental probes. This article first summaries the current understanding of the structure and properties of hydrates， then follows the review on the study of nucleation process based on the molecular dynamics simulation. Finally， with the emphasis on ultrafast nonlinear optical spectroscopy， the advances on experimental study of hydrate formation process are discussed， and future research directions are proposed.

Utilizing the time-resolved terahertz spectroscopy， the optical property of platinum selenide （PtSe2） thin films with different thicknesses in terahertz band are investigated experimentally. As the applied pump fluences increase from 0 to 2 540 μJ/cm2， the conductivity of 11 nm-PtSe2 film increases and further leading to the attenuation of the transmitted terahertz wave. Conversely， the conductivity of 197 nm-PtSe2 film decreases with the enhanced pump fluences that induces the increase of the transmitted terahertz wave. These characters enable PtSe2 thin film to be a photoactive terahertz modulator， which shows an ultrafast （~14 ps） and broadband （0.2~1.8 THz） modulation （15%~35%） of terahertz waves. The research provides a potential PtSe2-based platform to the active and ultrafast photonic devices at terahertz frequencies.

Ultrafast laser with high power and short pulse duration plays a more and more important role in basic scientific researches， precision machining and biomedicine etc. Among the various femtosecond light sources， the laser diode directly pumped Yb-doped all-solid-state bulk femtosecond laser has become one of the research hotspots in the ultrafast laser because of its advantages of compact structure， low cost， reliability and excellent output performance. In particular， the Kerr lens mode-locked Ytterbium-doped all-solid-state femtosecond laser is expected to deliver both an average power of one hundred watts and an pulse duration less than one hundred femtoseconds at the same time. This paper summarizes the research results of Kerr lens mode-locked ytterbium-doped bulky material all-solid-state lasers that generated short pulses with high average power in recent years， and looks forward to it. It also gives a prospect and plan for realizing the mode-locking operations with average power of one hundred watts， pulse energy of ten microjoules and high-power GHz repetition rate， respectively.

Substantial progress has been made in the average power and pulse energy from the ultrafast thin-disk lasers since the invention of the thin-disk technology， promoting significantly the applications of the ultrafast thin-disk lasers in many fields such as fundamental research， industry，biomedical science， and so on. In this work， the development of the ultrafast thin-disk lasers with respect to the concept of thin-disk technology， the mode-locked thin-disk oscillators and thin-disk amplifiers is reviewed， and its future development prospect is presented.

With the development of ultra-fast and ultra-strong laser technology， the interaction between light and matters in the strong-field regime has been extensively studied. At the same time， the rapid development of spatial light modulation technology in classic optics provides a new degree of freedom for optical manipulation. In recent years， the combination between these two different fields， namely， driving the intense-laser-matter interaction by the spatially structured light fields， has become one of the research hotspots in strong-field science. Strong-field ionization and high-order harmonic generation are two fundamental and important physical processes in traditional strong-field community. Here， the effect of optical vortex beams in strong-field ionization and its related research progress are first introduced. Then， the latest works of gas high-order harmonic generation driven by vortex beams or cylindrical vector beams in the past decade are introduced. At last， we look ahead to the prospects of intense spatially structured laser fields in strong-field physics.

With the development of ultrafast optics and the in-depth research on topological insulator materials represented by Bi2Te3， the research on applying topological insulator thin films to ultrafast lasers and devices has developed rapidly， and a series of research results have been published in recent years. This paper reviews the research on ultrafast lasers and devices based on topological insulator materials by starting from structure characteristics and preparation methods， introducing their unique optical and optoelectronic properties， summarizing the research on their applications in ultrafast lasers and optical devices， as well as reviewing and discussing the achievements and challenges in this field. We also provide an outlook on further development directions on the application of topological insulator thin film materials in ultrafast optics.

Observations of the microscopic dynamics of biological systems and the ultrafast behavior of particles in materials science can help us understand the ultrafast response of biological systems and materials in a deeper and more microscopic way. The pump-probe microscope is a new characterization method combing the pump-probe technology and microscopic imaging. By selecting different detection modes，the micro-mechanisms of different systems can be explored and characterized. In this review，the principle of pump-probe technology is first introduced. Then three major nonlinear principle in pump-probe process （excited-state absorption，stimulated emission and ground-state depletion）， the construction of pump-probe microscope，and the current developments and applications of pump-probe microscopy in biomedicine and materials science are discussed.

A method for ultrafast group-velocity control with simultaneously broad bandwidth， large tuning range， and controllable direction is proposed. By aid of cascaded optical parametirc amplification， the linear intensity-modulation of pump will transfer to the linear frequency-phase modulation of chirped signal pulses， enabling the time shift of signal pulses after compression. The tuning range and direction of time shift can be flexibly controlled by tuning the slope of pump modulation. The proposed method supports a large response bandwidth because of no phase-matching requirement， and can control the group velocity for few-cycle pulses in principle. Its feasibility is demonstrated by using both sawtooth-profile and Gaussian-profile pump modulations. It can implement in conventional nonlinear crystals and thus has an application prospect.

Three heterojunction blend films composed of NDT-based small molecule with different treatment and performance （null substituents， hexyl-substituents， hexyl-substituents with solvent vapor annealing treatment） were investigated by femtosecond transient absorption spectroscopy.The transient absorption results show that the charge separation state is mainly evolved from exciton state directly for all the three heterojunctions. The largest charge separation yield is found in the hexyl-substituents blend film with solvent vapor annealing treatment and the longest charge separation state lifetime is found in the hexyl-substituents blend film without solvent vapor treatment. In combination with the electron-hole mobility results， a dynamics viewpoint of the increased charge separation state lifetime， the enhanced charge separation yield and the more balanced electron-hole mobility were provided for the explanation of the enhanced power conversion efficiency after hexyl-substituents and solvent vapor annealing treatment.This work also offers a guideline for performance optimization in the future.

The physical effects in layered MoSe2 excited by 400 nm short-wavelength pulse are researched by terahertz emission spectroscopy. The dependence of THz amplitude on pump power， azimuthal angle， and polarization angle shows that the THz radiation is mainly caused by the surface depletion field induced photocurrent and the second-order nonlinear polarization induced shift current. The contribution of transient photocurrent and shift current is 82% and 18%， respectively. The results could provide experimental support for the development and application of MoSe2-based devices in the field of ultra-fast optics.