A pair of special diffractive optical element (DOE) is used in the combining of six Nd:YAG lasers to obtain flat-top output beam. The function of this pair of DOE in the system has been discussed. The property of output beam distribution has been analyzed and simulated. Both the measured far field and near field intensity distributions match the simulated results. Combining output energy of 15.3J is obtained, and the transfer efficiency of the DOEs is about 81%.
For compact and lightweight LASERs, producing stable output laser beams in adverse environments，such as high-vibration and high-temperature shock is a global problem. A solid-state high-power pulsed LASER is developed in this study. This LASER adopts tightly set six-channel LD pumped configuration and a single-aperture output scheme employs mutual-injection and confinement technic. By applying the method "confining oscillation and amplification", LASER parameters are: 100 mm × 100 mm × 300 mm in block dimension, 1.06μm in wavelength, 10Hz, 9.66Jfirstname.lastname@example.org, beam quality 5mm × 2mrad, energy instability < 2%, and another beam: 3.1Jemail@example.com, beam quality 5 mm × 2.5 mrad. The LASER is compact, lightweight, highly reliable, and with high pulse energy and excellent beam quality, thus allowing long-pulse and short-pulse operations. The developed approach can be potentially used for future applications.
In allusion to the demand of infrared system test, the principle of Infrared target simulator and the function of the temperature control are presented. The key technology of High precision temperature control is discussed, which include temperature gathering, PID control and power drive. The design scheme of temperature gathering is put forward. In order to reduce the measure error, discontinuously current and four-wire connection for the platinum thermal resistance are adopted. A 24-bits AD chip is used to improve the acquisition precision. Fuzzy PID controller is designed because of the large time constant and continuous disturbance of the environment temperature, which result in little overshoot, rapid response, high steady-state accuracy. Double power operational amplifiers are used to drive the TEC. Experiments show that the key performances such as temperature control precision and response speed meet the requirements.
The mechanism and characteristics of evanescent-wave coupling in solid-state laser is analyzed theoretically and experimentally. The results shown that self-organized phase locking between laser modes can be realized by evanescentwave coupling in solid-state laser. Based on “mutual injection and evanescent wave” characteristics of corner-cube prism, the paper reveals that far-field output of corner-cube laser is the inner reason and mechanism of coherent combining distribution by theory of evanescent wave and its coherence is better than plane parallel resonator. And “mutually coupled phase locking of six lasers based cube-corner resonator” scheme is proposed on this basis.
Phase locking and coherent beam combination of two individual double-clad fiber lasers by a novel extra-cavity mutual
injection-locking method based on a corner-cube are proposed and experimentally demonstrated. Steady interference
stripes with high contrast ratio(about 81.7%) are observed. The output power of the phase-locked array exceeded 10W
and the power combining efficiency is about 80%. No power-restriction optical components are utilized in our phaselocking
experiment and the output power can be further up-scaled.
Hydrogen-free DLC films has been deposited by femtosecond laser pulse onto (1 0 0) p-type silicon
substrates. The laser used for deposition has a pulse energy from 0.4mJ to1.6mJ and pulse width of about 50
fs with the repetition rate of 1 kHz. The laser intensities on the target are from 0.7×1014W/cm2 to
2.8×1014W/cm2. Uniform and wear-resistant DLC films is deposited with fs laser ablating a high purity
graphite target at room temperature in vacuum. It is shown that the films has a good hardness ranged from
20 GPa to 30 GPa. Raman spectroscopy, X-ray Photoelectron Spectroscopy and micro-hardness are used to
analyze the comprehensive performance of the films, and the results show that the films deposited at the
laser intensity of 1.4×1014W/cm2 has better hardness and a higher sp3 content. The sp3 fraction of the films is
estimated to be as high as 45.6%.
Coherent combination of laser beam is an important and challenging area of laser science, and many researchers have demonstrated a lot of multiple laser-beam combining technologies and structures. In this paper, the coherent combining principle was discussed and a novel self-coherent-combining solid state laser based on corner cube cavity is reported, for which a corner cube was utilized as a terminal mirror. The authors found that the near-field intensity distribution profile of CCR laser was divided into six fan-shaped segments by dihedral angle lines and their images, while its far-field intensity distribution presenting good centralized profile as a strong peak surrounded symmetrically by six weaker peaks. In order to get quantitative coherence details of CCR lasers, spatial coherence of two conjugate laser beams were measured. The far-field distribution of the conjugate laser beams presented very clear interference pattern and the stripe contrast visibility was calculated as high as 0.74 indicating the coherence degree should be even more than 0.74.
A novel, practical, eye-safe solid state laser is described in this paper. Using adjustfree solid state laser with heat conductive cooling element, Ce-Nd:YAG materials, directional prism resonator and Cr4+:YAG passive Q-switch as the pump source for OPO, and with overlapped self-collimation structure, laser energy of 10.5mj, wavelength of 1.57 µ m, pulse width of about 6.3ns and beam divergence of 5mrad were obtained. Also, optical axes was steady under the condition that laser was operated for 30~60 seconds at 5Hz repetition rate.
There are four kinds of reflectors: 1, flat mirror; 2, common retroreflectors; 3, phase conjugate mirror (PCM) and 4, the fourth one. "Corner cube" belongs to 2. However, if the dihedral angle lines and their images of the corner cube are taken into account, it is recognized as super-conjugator. The terminal mirror of laser cavity is replaced by such an element, it has ability to compensate distortions inside the cavity and misalignments insensitive and has being rapidly used. How to perform nonlinear phenomena by a well known linear element? Here we show the essentials by way of special array concept.
A new kind of highly stabilized solid-state lasers have the ability of high anti-disalignment and unique stability. The resonator is consisted of directional prism reflector and plane output window. The biggest allowed disalignment angle of the reflector can be +/- 20, which is 2 orders of magnitude higher than plane-plane resonator. It can be certified from theoretic analysis and experimental measurements that the lasers with kind of construction not only have higher ability of anti-disalignment, but also can compensate optical distortion and inhomogeneity of all of the optical components in the resonator. It makes the optical density distribution uniform and avoids or reduces laser damage. Laser beam quality can be improved. Especially, this kind of lasers fit for the application in the situation of vibration and high power Q-switch laser output.