The generation and detection technology of high-field terahertz wave based on ultrafast laser and its applications on matter manipulation are introduced. The mechanism of the generation of strong-field terahertz wave includes： nonlinear effects in crystals， laser plasma interaction， terahertz free electron laser， and so on. Terahertz detection technology includes： electro-optical sampling， air biased coherent detection， single-shot detection， and so on. Finally， the application of strong-field terahertz wave in matter manipulation is introduced. Especially， it is pointed out that the combination of strong-field terahertz sources and the fourth generation X-ray source has broad application prospects in the characterization and control of matter properties.

We propose a highly-efficient broadband up-conversion technique， which enables the efficient production of broadband 2.5th harmonic lasers （centered at 421.5 nm） in the violet-blue region from fundamental Nd∶glass lasers （at 1 054 nm）. Based on the nonlinear mixing of a frequency-doubled Nd：glass laser and a broadband mid-infrared laser centered at 2 100 nm with an incident energy ratio of 4∶1， and a noncollinear configuration that enables simultaneous phase-matching and group-velocity matching， a broadband 2.5th harmonic laser with a pulsed energy of 12.4 J and a bandwidth of 10.4 nm （relative bandwidth bigger than 2%） is produced. These results indicate the potentiality of producing high-power violet-blue lasers in 100-TW scale， and provide guidelines for developing ultrashort ultraintense lasers at short-wavelengths.

This paper reviews the research status of the mechanism and technology of all-fiber mode-locked laser ultrashort pulses and bound state soliton generation based on graded index multimode fiber saturable absorber. Using this noval type of all-fiber structured mode-locking modulation device， the output the single pulse energy of conventional soliton in fiber laser can up to the order of nJ， meanwhile spatial mode-locking operation can be realized. As the all-fiber nonlinear saturable absorber， the graded index multimode fiber has important research significance and wide application in lasers， and provides an important technical approach for the generation of higher energy ultrashort pulses.

Space debris is increasing rapidly owing to the rapid development of aerospace technology， which occupies limited orbital resources and threatens the safety of spacecraft in orbit， even the falling of space debris also poses a serious scare to people. The laser ranging has the characteristics of short wavelength， small divergence angle， good direction， good monochromaticity， strong anti-interference and so on. It can significantly improve the accuracy of space debris orbit determination. This paper makes a more comprehensive theoretical analysis for the space debris laser ranging. The technological development process of space debris laser ranging is described from the aspects of laser mode， signal detection and reception and so on. The development of the space debris laser ranging technology of the kilohertz repetition rate of pulse bursts mode and the 100 kilohertz pulse bursts transceiver alternate mode is discussed， and daytime laser measurement techniques of space debris are explained. Ultra-high repetition rate laser ranging technology would be applied in space debris laser ranging， it provides a new method for the further improvement of space debris laser ranging capabilities.

The tunable mid-infrared femtosecond sources with broadband， tunable wavelength， stable carrier envelope phase and high average power are achievable through optical parametric amplification. In this review， the key techniques of optical parametric ampification systems working in the mid-infrared range are introduced， including but not limited， broadband optical parametrical amplification and dispersion manging techniques. After that， the research progress and development prospect of the mid-infrared femtosecond source based on optical parametric amplification are presented and discussed.

Alexandrite crystal is an excellent broadband tunable laser gain medium with long fluorescence lifetime， high saturation energy density， wide absorption bandwidth and excellent thermo-mechanical properties. In addition to the flash lamp pumping， a variety of visible light sources can also be used as the pumping source such as blue laser diodes， red laser diodes， green lasers， yellow lasers， etc. With the maturity and commercial application of laser diode technology， the alexandrite lasers pumped by red laser diodes have become a hot topic in the field of solid-state lasers. The characteristics of alexandrite crystal are firstly introduced. The domestic and international research progress of alexandrite lasers pumped by flash lamp， laser diodes， etc. are summarized， including continuous， Q-switched， mode-locked and ultraviolet lasers. Finally， the recent advances in their applications to dermatology， lidar， microscope， etc. are introducted and the future developments of alexandrite solid-state lasers are prospected.

The strong-field processes can be controlled by the waveforms coherently synthesized by multi-color laser pulses. By using the “temporal gate” formed by the optimized two-color chirped laser pulse in the frequency domain， the extension of cut-off energy in the high-order harmonic generation and the generation of isolated attosecond pulse are achieved. By considering the macroscopic propagation effects， the contribution of long-trajectory electron in the high-harmonic emission burst is suppressed， leading to the reduction of its duration， thus the isolated attosecond pulse with the duration of about 200 as is generated in the X-rays， which provides with new hints for producing ultrashort attosecond pulses in the experiments.

A transistor lasers have functions of both light emission of a laser and current control of a transistor and has many novel opto-electronic properties. Compared with short wavelength GaAs based transistor lasers， InP based long wavelength transistor lasers are more suitable for optical fiber communication systems. In this paper， the research progress of InP based long wavelength transistor lasers with emission wavelengths of 1.3/1.5 μm is introduced. The characteristics of long wavelength transistor lasers with different structures and the related device designs that can be used to improve the performance of the devices are discussed. Based on different waveguide structures， three types of edge emitting long wavelength transistor lasers have been reported up to now， which are shallow ridge， buried ridge and deep ridge transistor lasers， respectively. In the shallow ridge transistor lasers， multi-quantum wells are positioned in the p type doped base material. As a result， laser operation of an InP based shallow ridge transistor laser with 1.5 μm wavelength has been realized only at low temperatures. In the buried ridge transistor lasers， AlGaInAs multi-quantum wells are burried with current blocking InP layers. The fabrication process of the device is complex， which leads to a high cost. In the deep ridge transistor lasers， because multi-quantum wells are inserted between the emitter and the base layers， both the diffusion of p type dopant into the multi-quantum wells and the optical absorption of the p type base material can be reduced noticeably. Room temperature operation of InP based deep ridge transistor laser with 1.5 μm wavelength has been fabricated successfully. Numerical simulations show that by n type doping in the multi-quantum wells or introducing a current confinement aperture in the emitter ridge， the effects of the nonradiative recombination centers can be reduced greatly.

Laser nano-fabrication technology of high-molecular polymer is an international research focus in the field of precision manufacturing. Based on the nonlinear effect of two-photon， multi-photon nonlinear effects and photoexcitation-photoinhibition mechanism， laser fabrication technology has broken the limits of optical diffraction， realizing a maskless rapid fabrication of three-dimensional complex nanostructures， which powerfully provides efficient solutions for the nanostructure fabrication demands in relevant fields. In this paper， the development history of laser high-molecular polymer nano-fabrication technology was briefly reviewed， and the principle of realizing nano-precision fabrication through laser and corresponding technology characteristics were described in details. Moreover， the new development and applications of laser nano-fabrication technology in the fields of micro-nano optics， optical information storage， biomimetic materials， biomedical diagnosis and treatment and so on were summarized. Eventually， challenges in laser nano-fabrication technology of high-molecular polymer and its future development were prospected.

Broadly tunable lasers are useful for basic spectroscopy studies， as well as a wide range of applications from optical communications to biomedical imaging. Transition-metal-ions doped solid-state gain media are eminently suitable for generating broadband emissions. Ti3+：sapphire and Cr4+：YAG crystals are 2 successful examples that are now widely used. Glass-clad Ti3+：sapphire and Cr4+：YAG crystal fibers have shown superior performance for broadly tunable lasers in the near infrared wavelength ranges. The tunable Ti3+：sapphire crystal fiber lasers are efficient， and have demostrated the lowest threshold over a 180 nm tuning range. The Cr4+：YAG crystal fiber laser shows a tuning range of 170 nm， limited by the excited state absorption. To celebrate the 60th anniversary since laser invention， a brief historical review and the latest developments of the Ti3+：sapphire and Cr4+：YAG crystal fiber lasers are discussed in the manuscript. The tunable Ti3+：sapphire crystal fiber laser's wavelength sweeping speed is envisioned， and the optical properties are compared with that of the Cr4+：YAG crystal fiber. With well-developed crystalline cores and clads for broadly tunable lasers， it is expected that novel applications， such as ultra-broadband optical fiber communications and cellular-resolution optical coherence tomography， could be evolved to meet the high data rate and high image resolution needs in future.

The feasibility of a 10-million-resolution virtually imaged phased-array spectrograph with a laser frequency comb as the calibration source is studied based on the virtually imaged phased-array dispersion characteristics. The numerical simulations propose two design schemes under extreme conditions with respective pros and cons. A simulated 2D spectral image is provided that satifies the the resolution of 10 million with simultaneous calibration using general parameters. Finally， the performance of such spectroscopy in some foreseeable applications is discussed briefly.

Based on a silicon-on-insulator material platform with a core thickness of 220 nm， a 64-channel silicon-based optical phased array integrated chip with a large deflection angle was designed using the beam propagation method and the finite time domain difference method. The chip was fabricated using electron beam lithography and other processes， and the performance was characterized. The key beam splitter and the far-field interference image of the arrayed waveguide were simulated. The simulation results show a beam splitting efficiency higher than 49.7% and a deflection range greater than 31°. The chip was fabricated using a standard silicon process on an insulating substrate and packaged as a whole. A self-feedback voltage modulation system optimized based on particle swarm algorithm was used for phase modulation. The test results show that under voltage modulation， the light spot produces a horizontal deflection greater than ±30°； at the same time， under the wavelength modulation of 1 550~1 610 nm， the vertical range also has a deflection of 8.4°. It is expected to be widely used in fields such as autonomous driving and unmanned aerial vehicle.

Nitrogen gas pumped by circularly polarized femtosecond laser pulses gives rise to bidirectional lasing emission， which holds unique potential for remote optical sensing application. However， the presence of oxygen molecules strongly suppresses this lasing effect. The influence of O2， Kr， Ar and He on the lasing effect of nitrogen molecules was compared， and the fluorescence of nitrogen molecules in pure nitrogen and ambient air was examined. It is observed that the lasing presents a similar quenching effect with the partial pressure of O2 and Kr， since Kr has a close ionization potential compared to O2. In contrast， for He which has a much higher ionization potential， there is no significant quenching effect. Therefore it is suggested that the quenching effect of O2 on nitrogen molecules mainly stems from the fact that O2 leads to a reduction of the clamped laser intensity inside the plasma filaments， which results in a decrease of the kinetic energy of the free electrons and an inefficient collision excitation.

Based on the off-axis integrated cavity output spectroscopy technology， an infrared carbon dioxide （CO2） sensing system was developed. A distributed feedback laser centered at 1 572 nm was used， and the absorption line of CO2 at 6 359.96 cm-1 was selected as the target line. The length of the resonant cavity developed is 60 cm， and the measured effective optical path is 1 200 m. Using the wavelength modulation spectroscopy technique and the direct absorption spectroscopy technique to measure the absorption spectrum of CO2， the signal-to-noise ratio of the spectral signal of the former was 130， which was better than the latter's signal-to-noise ratio of 80. The wavelength modulation technology was combined with the off-axis integrating cavity technology， and LabVIEW software was used to extract the second harmonic amplitude. Using the equipped gas samples， performance tests such as sensor calibration， stability and dynamic response were carried out. Using pure nitrogen （N2） for stability test， Allan variance showes that the detection limit of the system is 5.1×10-6 when the average time is 96 s. When the gas flow rate is 500 sccm， the experimental response time is less than 20 s. The system was used to carry out continuous online real-time monitoring of atmospheric CO2 concentration for 16.5 hours and detection of CO2 content in human breathing gas， both showing good performance. The system has the advantages of easy operation， fast response and high sensitivity， and can be widely used in atmospheric environment detection and medical diagnosis in the future.

A novel method for measuring Doppler Frequency Shift （DFS） based on dispersion-tuned Actively Mode-Locked Fiber Laser （AMLFL） technique is proposed and successfully demonstrated. The measurement principle is based on the fact that the output wavelength of the actively mode-locked fiber laser is linearly related to the Radio Frequency （RF） applied to the modulator in the laser cavity with large dispersion， so that the input frequency and further the DFS can be obtained by measuring the output wavelength of the AMLFL. Influences of system parameters such as the laser cavity length， dispersion， and mode-locked orders on the system performance are theoretically analyzed. Under the guidance of the simulation and for different application condition， two experiments are designed respectively based on long Dispersion-compensated Fiber （DCF） and Linearly Chirped Fiber Bragg Grating （LC-FBG） to provide large dispersion， and DFS measurements are conducted when the carrier frequencies are respectively 12.2 MHz， 265 MHz， 682 MHz and 1.118 7 GHz. The technique has advantages of simple configuration and flexible design， and may have potential application in measurement of Doppler frequency shift.

Doppler wind measurement lidar system based on Fabry-Perot etalon was developed. The laser emission wavelength is 532 nm. The 300 mm diameter telescope is used to receive the echo signal， which can simultaneously detect the wind field from the boundary layer to the top of the troposphere in China. In order to improve the accuracy of Fabry-Perot etalon transmittance curve scanning， the three-channel Fabry-Perot etalon spectrum is directly scanned by pulsed light on the basis of strict installation and adjustment of the receiver optical path. The pulse signal is collected by high-speed acquisition card， and the accurate pulse signal intensity is obtained by fitting integration method. Using nonlinear least squares fitting method， the spectral widths of FPI-1， FPI-2 and FPI-L are 1.20 GHz， 1.22 GHz， and 1.18 GHz， respectively. The peak transmittance of FPI-1， FPI-2 and FPI-L is 0.817， 0.807， 0.768， respectively. The peak-to-peak spacing of FPI-1 and FPI-2 is 3.91 GHz and the peak-to-peak spacing of FPI-1 and FPI-L is 1.25 GHz. In the wind field observation test， the radial wind speed was measured multiple times in the same direction. 91% of the measurement variance was less than 4 m/s. In horizontal wind field observation， the system has a detection height of 13 km during the day and 17 km at night. Compared with the air balloon， the agreement is good from 2 km to 10 km.