The influence on the level of amplified spontaneous emission (ASE) contrast resulting from the different seed pulse energies has been experimentally studied in a 10-TW-level femtosecond Ti:sapphire chirped pulse amplification laser. It is found that, with the seed pulse energy increasing, the ASE pedestal is suppressed more efficiently, and the ASE contrast is improved with a saturable tendency. The measurement of ~2×10^-8 ASE contrast in the range of more than 50 ps before the main pulse is achieved in the laser.

We suggest and demonstrate an approach to generate a femtosecond multi-terawatt pulse train at repetition rate of 100 MHz in a 10-Hz chirped pulse amplification Ti:sapphire laser system. With an electro-optic Q-switch regenerative amplifier, we can obtain an adjustable repetition-rate chirped pulse train. After amplification and compression, the 100-MHz pulse train with 46-fs pulse width and 1-TW peak power per pulse is obtained in our 10-TW-class Ti:sapphire laser system.

A spectroscopic method to determine thickness of quartz wave plate is presented. The method is based on chromatic polarization interferometry. With the polarization-resolved transmission spectrum (PRTS) curve, the phase retardation of quartz wave plate can be determined at a wide spectral range from 200 to 2000 nm obviously. Through accurate judgment of extreme points of PRTS curve at long-wave band, the physical thickness of quartz wave plates can be obtained exactly. We give a measuring example and the error analysis. It is found that the measuring precision of thickness is mainly determined by the spectral resolution of spectrometer.

Micro-lens arrays were adopted to homogenize the beam profile of 532-nm pumping laser for the main amplifier of an intense femtosecond, chirped pulse amplification (CPA) Ti:sapphire laser. Experimental measurements showed a great improvement of the near-field pattern of the CPA beam after the main amplifier and the size of the focal spot was improved from 2.7 times diffraction limitation (DL) to 1.6 DL. The spot size focused by an f/4 off-axis parabola (OAP) in the target chamber was measured to be 5.8 micron (full-width at half-maximum (FWHM)), and a peak intensity of 2.6*10^(20) W/cm2 was obtained at the output power of 120 TW. Peak intensity exceeding 10^(21) W/cm2 or even 10^(22) W/cm2 can be expected with smaller f-number focusing configuration and wavefront correction.

In this paper, a simple method of phase correction by using a micromachined deformable mirror (MMDM) is demonstrated. With correction of high-order phases due to propagating through medium, we obtained a clean pulse shape, flattened spectral phase and decreased the femtosecond laser pulse duration. It is shown by our experiment that the deformable mirror is an effective and easy method for adaptive phase correction.

With a tabletop hybrid Nd:YAG-Nd:glass laser as pump source, a compact optical parametric chirped pulse amplification (OPCPA) laser system with a peak output power of 16.7 TW and a pulse duration of 120 fs has been demonstrated. Chirped pulses are amplified from 50 pJ to more than 3.1 J with an energy gain of above 6×10^(10) by three LBO optical parametric amplifiers with a pump energy of 12.4 J at 532 nm. After compression, a final output of 2.0-J/120-fs pulse is obtained. To the best of our knowledge, it is the highest peak output power from an OPCPA laser so far. In addition, a practical design of 1-PWlaser system based on the technique of OPCPA is also proposed.

报道主-被动和纯被动对撞脉冲锁模Nd3+∶YAG激光器的实验研究结果.主-被动锁模激光脉宽为15ps,激光输出序列脉冲能量起伏小于±2%.被动锁模激光脉宽为12ps,序列脉冲能量起伏小于±1O%.利用腔内插入标准具,获得脉宽在15～26ps间可变的锁模激光.实验还研究了非共振环形腔的激光偏振特性.