In imaging detection of Lyman-a line of solar spectrum, in order to maintain spectral purity, a narrowband 121.6 nm minus filter is in urgent demand. Here, first-, second-, third-order narrowband 121.6 nm minus filters are designed, fabricated, and test. We just give our initial results, and due to complexity in characterization of optical constants in 115-130 nm, there are still significant deviations between design and experimental results.
When the meteorological satellite exploring geospace, it is necessary to confirm the imager attitude in inertial coordinate system in order to calculate the geographic situation of imaging target. In this paper, the calibration methods of the space coordinate system are described. The transformation matrix characteristics in the various methods are compared. At last the transformation matrix between aurora imager coordinates and satellite coordinates is measured by an efficient method. The results show that the calibration accuracy of the method is better than 1 arc second.
In this article, we report on the up-conversion fluorescence and laser characteristics at 852nm in Er<sup>3+</sup>-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 Er<sup>3+</sup>-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.
New wavelength fiber laser is one of the most interesting research hotspots of fiber laser science. In this paper, the
850nm band room-temperature up-conversion fluorescence of erbium doped silica optical fiber pumped by two LDs
(with 800nm and 792nm emission wavelength respectively) is firstly reported, which maybe helpful for the research of
850nm fiber lasers (the first telecommunication window). The possible up-conversion mechanisms involved are
discussed in terms of ground and excited-state absorption. The 800nm band absorption spectrum and 850nm wavelength
band up-conversion characters are experimentally studied.
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 compact all fiber Q-switched fiber laser based on an Er/Yb co-doped fiber (EYDF) is demonstrated. Two Bragg gratings (FBG1 and FBG2) were employed as the cavity mirrors. The Average output power, single pulse energy and pulse width of the fiber laser at different pumping powers and different repetition rates was studied. The output
spectrum of the fiber laser is 0.5 nm. At maximum launched pump power of 558mW, pulse energy of about 50μJ and duration of 140ns was obtained at the repetition of 2 kHz.