The coupling efficiency of the pump coupler determines the pump light injection capacity of a laser system. We have designed a pump coupler in a series connection, of which two or more pump couplers are spliced together through signal fibers to form a new pump coupler with high coupling efficiency and high output power. In the experiment, 3×1 end-pumping couplers and (2+1)×1 side-pumping couplers were made respectively and the two couplers were spliced to form a series connection. Six LDs with output power of about 200 W respectively were spliced with the six pumping arms of the new pump coupler. A total output power of this series connection pump coupler was about 1160 W, corresponding to a coupling efficiency as high as 98%. The loss of signal light was less than 0.4%.
The results of a theoretical study of pump absorption properties in the colinear side-pumping schemes with pumping loops and absorption loops are presented. For side-pumping schemes with pumping loops, the number of pumping loops affects the pump absorption obviously: the more pumping loops, the higher pump absorption; and the pump light is absorbed effectively after propagating through all the loops. For side-pumping schemes with absorption loops, more loops results in a larger doped region, which leads to higher pump absorption efficiency.
High quality permanent connection between optical fibers is a significant issue in optics and communication. Studies on room temperature optical large diameter fiber-fiber direct bonding, which is essentially surface interactions of glass material, are presented here. Bonded fiber pairs are obtained for the first time through the bonding technics illustrated here. Two different kinds of bonding technics are provided-fresh surface (freshly grinded and polished) bonding and hydrophobic surface (activated by H2SO4 and HF) bonding. By means of fresh surface bonding, a bonded fiber pair with light transmitting efficiency of 98.1% and bond strength of 21.2 N is obtained. Besides, in the bonding process, chemical surface treatment of fibers' end surfaces is an important step. Therefore, various ways of surface treatment are analyzed and compared, based on atomic force microscopy force curves of differently disposed surfaces. According to the comparison, fresh surfaces are suggested as the prior choice in room temperature optical fiber-fiber bonding, owing to their larger adhesive force, attractive force, attractive distance, and adhesive range.
Solar EUV band has a very important meaning of detecting the physical processes and its controlling factors of solar
surface, and the Earth's environment as well as changes in the Earth's climate.
In the thesis we introduce the basic design of the solar ultraviolet telescope and imaging system .Because of small-band
transmission of the vacuum ultraviolet optical prism, we take double-Cassegrain reflector optical system. The sunlight
could be gathered to CCD detection system in order to image the sun in three specific spectrums involving 30.4nm,
58.4nm and 121.6nm. The reason we choose the center wavelength of 30.4 nm. 58.4nm and 121.6nm is that these three
spectrums contain a lot of bright lines, have a great radiation flux and play a significant role in ionizing and heating the
Earth's upper atmosphere.
We make UV telescope imaging system and ultraviolet light as a whole, then pump the whole system into vacuum to
simulate space environment. We introduce the calibration device in our system innovatively. Our thesis gives a detailed
description of the way of simulation of optical design, the vacuum system design and system calibration. Owing that our
system have the characteristic of Lightness, simple structure, small power, it is rather fit for astronomical observations on
the moon. The imaging results could provide very important research data for the middle and upper atmospheric
composition and ionospheric electron changes in density and communications research.