Laser diode end-pumped passively Q-switched Nd:YAG/Cr<sup>4+</sup>:YAG micro lasers, with short pulse width, high repetition rate, high peak power and compact structure, have widely applications in laser mico processing, optical communication, laser radar, medical and other fields. But its beam quality is not excellent because of short resonant cavity, thermal effect of crystal, and pump laser. The beam quality is promoted in this paper by compressing the pump beam size and confirming the best position of pump beam focus in crystal. The repletion rate of laser is 20kHz. The output single pulse energy is 18.2μJ and pulse width is 1.23ns. The beam quality of laser is M<sup>2</sup>=1.18.
In this paper, on the basis of the theory of quasi phase matched, CO<sub>2</sub> laser spectrum corresponding to GaAs chip within the scope of the matching length was calculated. Through the numerical solution of the wave equation, the relationship between power density of pump laser and frequency doubling conversion efficiency was given under the different crystal length conditions. By adjusting the CO<sub>2</sub> laser gas mixture components, we optimized the pump laser pulse wave to meet the requirements in the temporal distribution of the pump light. On the other hand, we optimize the output beam mode to meet the pump light distribution in space requirements. We use the tunable TEA CO<sub>2</sub> laser as the light source to pump quasi phase matching GaAs crystal, When the pump wavelength is changed from 9.23μm to 10.75μm range, the conversion efficiency of frequency doubling output is greater than 4%, when the pump wavelength is 10.68um, the frequency doubling efficiency reached 6.58%.
A high average power and high beam quality nanosecond laser is presented that is based on CW diode side-pumped Nd:YVO<sub>4 </sub>grazing-incidence slab amplifier. A TEM<sub>00</sub>, passively Q-switched diode-pumped Nd:YAG laser as the seed laser, generating a M<sup>2</sup> ≈1.3 beam train of 0.25W, 2.3ns pulses with adjustable repetition rate in the range 5-20kHz. After double-pass amplification, more than 20W of output power with a beam quality of M<sup>2</sup> ≈1.4 is obtained at an optical-optical efficiency of 35%. The high brightness of this laser system seems ideal for nonlinear optics and laser processing applications.
In this paper a Xenon-lamp-pumped four rods pulsed Nd:YAG laser is presented. The influence of offset angle of
Nd:YAG rods and thermal stable regions in the resonator have been analyzed theoretically, and tolerance of offset angle
and is given. A plane-plane symmetrical resonator has been used in the experiment, and the distance between two
neighbor rods is two times of that between the mirrors and rods. While input electric power is 58 kW and the duty cycle
is 17%, an output laser with an average power of 2026 W, a peak power of 11.9 kW, maximum single pulse energy of 60
J and a beam parameters product of 24.5 mm×mrad has been obtained. The electro-optical conversion efficiency is
3.49 %, and instability of the laser is less than 2 %.
This paper introduces a novel kind of E-O Q-switched Nd:YVO4 compact laser with ultra-narrow pulse width. In this
paper, the general equations describing Q-switched laser operation are given and the factors about cavity length, laser
gain medium, the loss inner resonator and pump energy to influence the laser pulse width are analyzed theoretically. These parameters greatly optimized experiment. The fiber-coupled laser-diode end-pumped laser we developed
simplifies the conventional structure of E-O Q-switched lasers. The cavity length is effectively reduced to 19mm to narrow the pulse width. The pulse width of 1.049ns is obtained and the single pulse energy reaches to 0.32mJ. This 1
nanosecond laser has the advantage in reliable and outstanding performance with simplified structure. Most importantly, we investigated the performance of an innovative RTP crystal in the Q-switched laser with high repetition frequency. It was experimentally proven that this narrow pulse width laser can operate with high repetition frequency because of the
novel Q-switched crystal RTP with great performance. Both theoretical analysis and experiment data demonstrate that sub-nanosecond pulses can also be produced with E-O Q-switching technique. Thus, this technique can be widely applied.
A method computing the absorption efficiency with the difference between pump power entering the thin disk and pump
power transmitted through the disk is introduced. Compared with directly computing the absorbed power, the method
presented here needs much less computation to achieve the same accuracy, making it possible to compare much more
absorption efficiency values at higher accuracy with a few parameters varied within certain ranges. Nonabsorption loss
values were calculated with absorption coefficient, array distance and round disk radius varied within certain ranges.
Results of calculation showed that the nonabsorption loss generally increases with increasing array distance, decreases
with increasing round disk radius and decreases with increasing absorption coefficient. The method introduced by this
paper presents a theoretical reference for the optimal design of thin disk lasers.
According to the requirement of high power laser beams and beam focus diagnostic instrument for measuring laser transverse intensity distribution, a new method of CO<sub>2</sub> laser rapid detecting by pyroelectric detector is given. The rapid response of photoelectric transformation with large enough gain is obtained. The response time is shorter than an order of magnitude comparing with common method. The detector can operate in normal room temperature, and need no cooling set. The photoelectric transformation system satisfies the measurement requirement of high power laser density cross-section distribution. The method can be employed for application concerning with rapid response of pyroelectric detector.
This paper reports on the characterization and analysis of drilling with a novel high power acousto-optical Q-switch pulse laser. The laser is a flash-lamp pumped pulse Nd:YAG laser which can be used in the free running mode with repetition rates up to 10Hz. Additionally it is possible to modulate these pulses using acousto-optical modulator which enables a burst between 1 and 10 Q-switch pulses with a duration of typically 200ns during each flash-lamp pulse. The repetition rate of the burst is 5kHz-50kHz, the pulse energy is 30-8OmJ, and the peak power is more than 400kW with a beam parameter product of about 5mm mrad. The drilling process and the combination of different repetition rate of the bursts enables drilling 2.5mmthick Cu and Ni-alloy for 0.2mm micro-hole. The recast layer is nanower. Oxidation of the walls of the hole is prevented by a high-pressure inert gas.
Using the method of rotating hollow probe, the measuring system which can directly measure laser transverse intensity distribution of high power laser beams/focus for laser processing is studied. The mathematical and physical models of measured laser beams/focus propagation in hollow probe are founded. According to the calculation, the system parameters, including pinhole diameter of hollow probe, dimension of propagation channel, dot number of sampling, are discussed. A new measuring system is designed. The measuring of high power laser beams/focus by this system is realized. The calculation results are satisfied with the measuring results. The instrument can measure CO<SUB>2</SUB> and YAG laser, measured power larger than 10kW, maximal measured power density up to 10<SUP>7</SUP>w/cm<SUP>2</SUP>, maximal diameter 60mm, laser focus minimal diameter smaller than 0.5mm.
The optical parametric process with ultrashort pulse is investigated theoretically and experimentally. Reliable numerical method is used. The comparison between the theory and the experiments shows the directing bearing of our work.