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Semiconductor laser (SL) can output chaotic lasers under external disturbances such as optical injection or optical feedback, and the bandwidth can reach up to GHz magnitude. External-cavity feedback semiconductor lasers can output high-dimensional chaotic lasers and are considered to be better sources of chaotic entropy. However, due to external cavity feedback and other effects, it will give rise to obvious external cavity time delay signature (TDS) in the output chaotic laser, which restricts the application of chaotic lasers. On the other hand, the bandwidth of chaotic laser determines the transmission rate of confidential communication, and therefore TDS and bandwidth are two important parameters that will affect chaotic laser’s applications. Therefore, it is significant to take appropriate measures to suppress the TDS and increase the bandwidth of chaotic laser output by semiconductor laser. In this paper the output laser from a semiconductor laser with single optical feedback is partially injected to another semiconductor laser with double filtered optical feedback. Thus they form a semiconductor laser system with external optical injection and double filtered optical feedback, i.e. a master-slave laser system which is used to suppress the TDS of chaotic laser and investigate its bandwidth. We numerically investigate the influences of external light injection coefficient, feedback intensity, pumping factor, and filter bandwidth on TDS. Then the suppression effects of this system on TDS are analyzed and compared with those of semiconductor laser system with external optical injection and single optical feedback, those of semiconductor laser system with external optical injection and double optical feedback, those of semiconductor laser system with external optical injection and single filtered optical feedback, and those of semiconductor laser system with double filtered optical feedback. The results show that the proposed scheme in this paper has the best suppression effect on TDS. Then the bandwidth of the chaotic laser output from the system is investigated under the condition of parameters of effectively suppressing TDS. The results show that the system proposed in this paper can increase the bandwidth of the system output chaotic laser by properly selecting the parametric values, and the maximum bandwidth value of the obtained chaotic laser is about 8.8 GHz. The above investigations indicate the effectiveness of the proposed scheme. The results of this investigation are significant for the application of chaotic lasers.

Extreme ultraviolet lithography is most promising for the next generation lithography. However, debris from laser-produced plasma, particularly energetic ions, severely decreases the lifetime of extreme ultraviolet optics. We measured the characteristics of ions from tin plasma by the time of flight method with a frequency-doubled Nd: YAG laser at the intensity of 3.5×1010 W/cm2 (532 nm, 8 ns). Our measurement shows that the maximum and peak of tin ions energies from plasma under the above experimental parameters are about 4.2 and 1.8 keV, respectively. Moreover, it is found that kinetic energy angular distribution of tin ions can be fitted by cos0.8(θ), where θ is the angle with respect to the target normal. We also investigated the mitigation effect of argon, helium gases to the tin ions, and found that tin ions from the plasma can be mitigated effectively at the pressure ∼38 mTorr for argon or ∼375 mTorr for helium, respectively.

We present a laser architecture to obtain continuous-wave blue radiation at 489 nm. An 809 nm diode-pumped the Nd:LuVO 4 crystal emitting at 916 nm. A part of the pump power was then absorbed by the Nd:LuVO 4 crystal. The remaining was used to pump the Nd:YLiF 4 (Nd:YLF) crystal emitting at 1047 nm. Intracavity sum-frequency mixing at 916 and 1047 nm was then realized in a LiB 3 O 5 (LBO) crystal to reach the blue radiation. We obtained a continuous-wave output power of 425 mW at 489 nm with a pump laser diode emitting 18.4 W at 809 nm.

Microwave guiding along double parallel lines of femtosecond-laser-generated plasma filament has been demonstrated over a distance of about 8 cm in air, corresponding to a maximum microwave signal intensity enhancement more than sixfold the free-space propagation. It is shown that the operating frequency and the line electric width influence the propagation coefficient of microwaves propagating along this transmission line. Based on channeling microwaves along this line and by measuring and comparing the propagated microwave signals, the basic parameters of laser-generated plasma filament, namely, its electron density and conductivity, are obtained.

Laser induced plasma spectroscopy of alloy steel was produced by Nd : YAG pulsed laser at 1 064 nm, and the spectral signal was detected by high resolution and width controlled ICCD. Several Fe atomic spectral lines such as 404.581, 414.387, 427.176 and 438.355 nm were chosen for analysis, and the effects of different experimental parameters on LIBS spectral signal intensity were investigated. It is shown that the experimental parameters such as pulse energy, laser focus location and laser delay time have great influence on the LIBS signal. LIBS signals with high spectral intensity and signal-background ratio (SBR) as well as the optimum experiment conditions were obtained by optimizing these experiment parameters so as to make composition analysis of the alloy steel.

The abilities to trigger and guide high-voltage discharge by using single andemmultiple filaments/em(MFs) are experimentally studied. It is shown that the discharge voltage threshold can be reduced significantly in both regimes of single and MF; however, the MF does not gain a larger reduction than a single filament. This behavior of the MF is attributed to the single discharge path rather than simultaneous multiple ones as one might expect during the discharge process.

A comparative investigation of the resistance and ability to trigger high voltage (HV) discharge for a single filament (SF) and multiple filaments (MFs) has been carried out. The experimental results show that the trend of the breakdown threshold of the SF exactly follows that of its resistance, but this is not the case for the MF. The MF's resistance is much smaller than the SF's. However, the MF shows a slightly higher HV breakdown threshold than the SF. The underlying physics is that the measured resistance of the MF is collectively contributed by every filament in the MF while the HV breakdown threshold is determined by only one single discharging path.