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.
In this article, we report on the up-conversion fluorescence and laser characteristics at 852nm in Er3+-doped silica optical fiber excited at 800nm wavelength band. The possible up-conversion mechanisms involved are theoretical discussed in terms of ground-state absorption, excited state absorption, up-conversion emission energy transfer and cross-relaxation between excited ion pairs and multi-phonon relaxations. Experimentally, the 700~900nm band absorption spectrum and 850nm band spontaneous fluorescence spectrum are measured and studied. By using two bi-directionally pumped LDs (with 800nm and 792nm emission wavelength respectively) and two Fiber-Bragg-gratings (FBG@852nm), an all-fiber based 852nm up-conversion laser system is built to study the lasing characteristics. These results suggest that Er3+-doped silica fibers are potentially useful materials for developing up-conversion lasers and optoelectronic devices, especially helpful for the first telecommunication window (at 850nm band) lasers and amplifiers.
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.
An alignment-free directional prism resonator that ensures the laser TEM00 mode with thermal stability in a certain range is designed by using g* parameter equivalent method. The output of all solid state laser is about of 150mJ, and the beam divergence is of 3mrad with 20Hz repetition rate, moreover, when the laser operates from 10 to 30Hz, the beam divergence is steady. This laser meets the needs of special engineering application.