Generation of high-contrast and high-intensity laser pulses using an OPCPA preamplifier in a double CPA, Ti:sapphire laser system

We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 10¹⁰ within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 10²⁰ W/cm².     

预脉冲灯泵钛宝石可调谐激光器

利用预脉冲技术,可减小氙灯放电初始阻抗,使主放电电流脉冲前沿变陡,脉冲包络变窄,峰值变高,泵浦能量集中,有利于灯泵钛宝石激光输出。试验证明,在低能量（４７Ｊ）注入时,电光转换效率提高１８％,输出９５０ｍＪ;在高能量（１１６Ｊ）注入时,效率提高５％,输出能量１８１０ｍＪ。该激光器可调谐范围为６９５～９４０ｎｍ。     

High-power output from a compact OPCPA laser system

With a tabletop hybrid Nd:YAG-Nd:glass laser as pump source, a compact optical parametric chirpedpulse amplification(OPCPA)laser system with a peak output power of 16.7 TW and a pulse duration of120 fs has been demonstrated.Chirped pulses are amplified from 50 pJ to more than 3.1 J with an energygain of above 6×10~(10)by three LBO optical parametric amplifiers with a pump energy of 12.4 J at 532nm.After compression, a final output of 2.0-J/120-fs pulse is obtained. To the best of our knowledge,itis 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.     

A hybrid OPCPA/Nd:phosphate glass multi-terawatt laser system for seeding of a petawatt laser

To enhance radiographic abilities on its Z-Accelerator, Sandia National Laboratories is incorporating a petawatt laser system into the existing Z-Backlighter laser facility. As part of this work, a short-pulse laser has been constructed to seed the larger Beamlet type Nd:phosphate glass slab amplifiers. This seed laser consists of an optical parametric chirped pulse amplification (OPCPA) system joined to a Nd:phosphate glass rod amplifier system in order to achieve multi-Joule sub-picosecond operation. The rod amplifier system has been modeled using the Miró code which shows good agreement with the experimental results. This system can achieve focal intensities up to 10¹⁸ W/cm² at a repetition rate of once every 20 min and has been applied to produce k-alpha X-rays in copper.     

Development of a Ti:Sapphire DIAL system for pollutant monitoring and meteorological applications

A mobile differential absorption lidar system with SHG of Nd-YAG pumped Ti : Sapphire laser has been developed and tested. Mixing between Ti : Sapphire and Nd-YAG fundamentals extends the wavelength range to UV–vis region (250–480 nm), which is ideal to monitor tropospheric pollutants. Preliminary water vapor profiles in the near IR region (in our case 800–900 nm) are presented and discussed.     

New progress in Ti:Sapphire laser pumped by copper vapor laser

Because the copper vapor laser(CVL)can supply high average output power of severalhundred wattes and it's emission spectra are an excellent match for the absorption band of Ti:sapphire,the potential application of Ti:sapphire laser pumped by CVL is increasing greatly.     

High power all-solid-state quasi-continuous-wave tunable Ti: sapphire laser system

This paper reports a high power, all-solid-state, quasi-continuous-wave tunable Ti:sapphire laser system pumped by laser diode (LD) pumped frequency-doubled Nd:YAG laser. The maximum tuned output power of 4.2 W (797 nm) and tuned average power of 3.7 W were achieved when fixing the Ti:sapphire broadband output power at 5.0 W and applying 750-850 nm broadband coated mirror.     

Femtosecond laser filamentation with a 4 J/60 fs Ti:Sapphire laser beam: Multiple filaments and intensity clamping

Laser Physics - We used both the backscattered nitrogen fluorescence signal (BSF) and ICCD fluorescence side imaging methods to study the filament light intensity with a 4 J/60 fs Ti:sapphire laser...     

掺钛蓝宝石脉冲可调谐激光器在实验室中的应用

介绍了掺钛蓝宝石可调谐激光器在实验室中的应用.自行设计了波长690~900 nm之间连续可调谐激光,单脉冲能量为5 mJ,重复频率为20 Hz,激励采用波长532 nm、能量35 mJ的倍频YAG激光器,经过调谐滤波器,输出连续可调谐激光.     

Interaction of femtosecond pulses of a two-harmonic Ti:Sapphire laser with liquid media

The interaction of ultrashort laser pulses having wavelengths of 400 and 800 nm with liquid media, including organic solutions, has been experimentally studied. It is shown that transparent drops evaporate and boil (with partial mass ejection in the form of vapor and liquid fragments) in the field of ultrashort light pulse. A large-scale change in the spectrum of laser pulse during its interaction with a water particle is revealed. This change is caused by self-modulation of the light phase due to the Kerr optical nonlinearity of liquid and the formation of plasma. Filamentation in continuous liquid media is analyzed; specifically, the dependences of the number of filaments, the lasing spectrum width, the nonlinear-focusing distance, and the filamentation region diameter on the laser pulse power are measured. It is noted that there is a range of relative powers where the number of filaments very rapidly increases. It is shown that the spectral broadening at filamentation, observed for fixed pulse energy with a change in pulse width, overlaps the entire visible spectral range. This circumstance makes it possible to obtain width-tunable pulses and use them, e.g., in optoacoustic diagnostics of media.     

Materials processing by use of a Ti:Sapphire laser with automatically-adjustable pulse duration

We have developed an automatic pulsewidth-adjustable femtosecond Ti:Sapphire laser system that can generate an output of 50 fs-1 ps in duration, and sub-mJ/pulse at a repetition rate of 1 kpps. The automatic pulse compressor enables one to control the pulsewidth in the range of 50 fs-1 ps by use of a personal computer (PC). The compressor can change the distance in-between and the tilt angle of the grating pairs by use of two stepping motors and two piezo-electric transducer(PZT) driven actuators, respectively. Both are controlled by a PC. Therefore, not only control of the pulsewidth, but also of the optical chirp becomes easy. By use of this femtosecond laser system, we fabricated a waveguide in fused quartz. The numerical aperture is chosen to 0.007 to loosely focus the femtosecond laser. The fabricated waveguides are well controllable by the incident laser pulsewidth. We also demonstrated the ablation processing of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂), which is a key component of human tooth and human bone for orthopedics and dentistry. With pulsewidth tunable output from 50 fs through 2 ps at 1 kpps, the chemical content of calcium and phosphorus is kept unchanged before and after 50-fs-2-ps laser ablation. We also demonstrated the precise ablation processing of human tooth enamel with 2 ps Ti:Sapphire laser. PACS 42.65.Re; 42.62.-b; 42.70.Ce; 42.82.Et; 61.80.Ba     

Hundred mJ, sub-picoseconds, high temporal contrast OPCPA/Yb:YAG ceramic thin disk hybrid laser system

The authors have demonstrated an optical parametric chirped-pulse amplification (OPCPA)/Yb:YAG ceramic thin disk hybrid laser system having hundred mJ level pulse energy sub-picosecond pulse duration with high temporal contrast. At an input chirped-pulse energy of 3.8?mJ from an OPCPA preamplifier an output energy of 130?mJ has been generated from multipass diode-pumped Yb:YAG ceramic thin disk amplifier. A recompressed pulse duration of 450?fs with a contrast level of less than 7.2×10^?9 at ?150?ps before the main pulse has been obtained. The contrast level is the highest value achieved in Yb:YAG chirped-pulse amplification (CPA) laser system at 100?mJ level.     

A novel high-peak power double AO Q-switches pulse Nd:YAG laser for drilling

This paper reports on the characterization and analysis of a novel high power with double acousto-optical (AO) Q-switch pulse laser. It is shown that two AO Q-switches, in which acousto-fields are perpendicular to each other, switch-loss is nearly three times larger than one AO Q-switch, one time larger than the two AO Q-switches in which acousto-field are parallel. The laser pulse bursts, with 5–50 kHz repetition rate of the burst, typically 200 ns duration, 400 kW the peak power, 5 mm mrad beam parameter product, are obtained. Using the laser for drilling, the perfect drilling results are given to a thinner recast layer.     

Tunable no-tracking OPO-OPA tandem in the near-infrared pumped by a Ti:Sapphire laser

We report the performance of a type-II KTP optical parametric oscillator-amplifier tandem pumped in a non-critical phase-matching configuration by a flashlamp-pumped Ti:Sapphire laser, scanned from 730 to 900 nm. Tunable signal and idler wavelengths are generated from 1.065 to 1.290 µm and from 2.320 to 2.970 µm, respectively, without crystal tracking. Slope efficiency is as high as 32% for the signal conversion only. A KNbO₃ crystal has also been tested as a parametric amplifier in a no-tracking configuration and yields comparable gain.     

提高灯泵钛宝石激光器效率的技术途径

介绍了几种提高灯泵钛宝石激光器效率的技术途径,包括脉冲氙灯参数的选取,放电电流的优化,泵浦腔几何结构的设计,光学谐振腔参数的优化和输出耦合镜最佳透过率的选取。通过以上各项技术的完善,激光效率得到明显提高,从０．５％到２％［１］。     

Flashlamp-pumped Ti:Sapphire laser: Influence of the rod figure of merit and Ti3+ concentration

A flashlamp-pumped Ti:Sapphire laser is tested with rods of various Figures of Merit (FOM from 100 to 800) and Ti³⁺ concentrations (0.1 and 0.15% by weight) and we measured the laser energy dependence as a function of these parameters. Output energies above 2 J are obtained without dye converter, leading to a 1.8% overall efficiency and a 2.2% slope efficiency. The effects of pump pulse duration by variation of the discharge capacitance are also monitored.     

自锁模钛宝石激光器多脉冲运转特性研究

对自锁模钛宝石激光器中多脉冲的特性和成因进行了较详细的分析，提出了腔内脉冲周期性散射减弱了腔内自振幅调制的理论模型。据此所作的数值模拟结果，很好地解释了实验现象。     

Tunable single-mode pulsed Ti3+:Sapphire laser injection-seeded by a continuous-wave Cr3+:LiSrAlF6 laser

Spectrally pure high-power tunable single-mode operation of a pulsed Ti³⁺:sapphire laser by a tunable injection-seeding is reported. The injection laser was a cw diode laser pumped, spectrally narrowed tunable Cr³⁺:LiSrAlF₆ (Cr³⁺:LiSAF) laser with a grating in the auxiliary cavity. Single-mode tunable operation of a pulsed Ti³⁺: sapphire ring oscillator was obtained at different wavelengths in the range between 818 nm and 848 nm with a typical linewidth of 0.006 cm^-1. To extend the applicability of this operation to a differential absorption lidar system, the single-mode Ti³⁺:sapphire oscillator output was amplified and a high energy output of 38 mJ was obtained with the same linewidth.     

掺钛蓝宝石再生放大器的光谱整形

采用腔内和腔外两种方法对激光脉冲进行光谱整形。在掺钛蓝宝石再生放大器中插入一定厚度的石英双折射晶体片，通过调节晶体光轴的空间取向，对再生放大器输出的脉冲光谱进行腔内整形，使再生放大器输出脉冲的谱宽从20nm左右增加到35nm左右，接近进入再生放大器的激光种子脉冲的谱宽。另外用镀反射膜的平板滤光片进行了腔外光谱整形的实验，使再生放大器输出脉冲谱宽展宽到28nm左右。