[en] The design principle and structure of a high efficiency frequency-converting system used on LF-11 laser facility are presented. The conversion rates, the allowable mismatching angle for the KDP crystal, the far-field divergence angle, near-field intensity distributions, and time profiles of the ω₀ and 2ω₀ laser beams are measured. Finally an ICF experiment is introduced with the 2ω₀ laser beam conducted for the first time in China

[en] Electro-optical switch with plasma electrodes is one of critical components in high power ICF drivers based on the large aperture multipass amplifier array scheme. To investigate problems related to this technology an 80 mm x 80 mm Pockels cell using a plasma electrode formed by a glow discharge on either side of a KDP crystal was designed and constructed and the switching performance was tested. The authors describe the configuration of the Pockels cell, the plasma electrode formation by glow discharge, the switch pulse generation and output performance, as well as the measurement of the switching speed and the switching efficiency across the aperture. Some typical results in the switching experiment are given

[en] Due to the requirement of laser conditioning system of ICF drive, a Nd:YAG laser system with high power and high beam quality is developed. Compared to current common laser system, it has an apparent improvement in temporal shape and beam quality. The system applies several technologies and teaches as following: a single longitudinal mode oscillator with a passive Q-switch; SBS pulse compressing technology; SBS pulse phase-conjugation technology; image relay technology and high efficient pumping cavity. Its main technology indexes are listed as pulse width 3ns, energy 1.1J, far field diverge angle 0.3 mrad, repetition frequency 10 Hz

[en] Among solid-state laser amplifiers, regenerative amplifiers which have the advantages of high gain, good beam quality and simple structure, have been widely concerned and applied. After decades of development, regenerative amplifiers are able to realize pulse energy of several hundred millijoules and average power of several kilowatts in stable operation. The output performance of regenerative amplifiers is determined by properties of gain media, structure of cavity, pump condition, thermal effect and qualities of components. The properties of gain media are the most essential factors. Because of different properties of materials, regenerative amplifiers based on different kinds of materials present different structure and performance. Based on different material systems, the key common problems encountered in the development process of regenerative amplifiers under various systems, as well as several typical types of regenerative amplifiers and their characteristics are introduced. The future development trend of regenerative amplifiers is discussed. (authors)

[en] Short communications only

[en] To meet the requirement on the quality and the stability of the output pulse from the fiber front-end system in ICF driver, the polarization characteristics of the fiber system have been analyzed and different polarization control technologies have been researched by the experiments. For the narrow spectral width (several pm) and short pulse (several ns) of the system, considering the requirement on the time character in the final output of the system, the special average depolarization has been adopted. As a result, the complete depolarization of the light signal can be realized efficiently and the stability of the system with the depolarizer achieves 1.72%. (authors)

[en] Short communications only

[en] Based on the broad-band pulsed laser amplification model of neodymium glass, the relationship between energy extraction efficiency of the pulsed laser amplification and input fluence, pulse widths and spectral bandwidths (or wavelength distributions) was studied by numerical simulation. The calculation results show that the energy extraction efficiency of the broadband amplification in neodymium glass increases with the increase of the input luminous flux, and finally tends to a certain value. For the medium with uniform broadening, the energy extraction efficiency decreases with the increase of the bandwidth. For the medium with non-uniform broadening, the energy extraction efficiency increases gradually with the increase of the bandwidth, reaching the maximum value, after which it declines. For a mixed widened medium with a uniform widened to non-uniform widened linewidth ratio of 0.1, using a broadband laser can achieve an efficiency improvement of approximately 80% under saturated flux input conditions. (authors)

[en] A Ring-LD-pumped Nd: YLF laser amplifier system is theoretically and experimentally discussed. A structure of off-axes double passes amplifier is used. The results of experiment shown that 109 mJ output energy with a net gain of 1115 is obtained under 150 μJ input energy; a compact side-pumped structure is used to obtain a high transferring efficiency of LD array, 1.01 J output energy is achieved at 1053 nm. (authors)

[en] Theory analysis were performed for ytterbium doped fiber amplifier (YDFA) on its characteristics of mismatching amplification on chirped-pulse with mid wavelength around 1053 nm. An excellent pulse can be achieved with optimistic input intensity and spectrum width. On the other end, by analyzing the phase-mode of YDFA's mismatch amplification, a good result was found. Although the phase-modulate was serious, the phase-modulate during YDFA mismatch amplification affected the quality of pulse after compression weakly