In nonlinear optical frequency conversion process, it is desirable to maximize the product of the intensity of pump laser and the interaction length in order to achieve maximum conversion efficiency. The purpose of this research is to obtain the maximum conversion efficiency on the premise of decreasing the dimension of photonic devices and realizing high-density optical integration. In this thesis, the design and method of manufacturing tapered fibers with a submicron diameter and the possibility of using optical-quality submicron-diameter tapered fibers are examined both theoretically and experimentally. The main work ranges from theoretical propagating properties, fabrication and experimental measurement of the nonlinear optical phenomena, to basic applications of these tapered fibers. In the study of silicon dioxide, we investigated its properties of energetics, calorifics, mechanics, optics and chemical stability. In the experiments, rather long and unbroken submicro-diameter optical fibers with low optical loss about 0.1dB/cm were fabricated with a new drawing process by heating the standard single mode fiber with a designed electric strip heater. Pumped by a 532 nm mode-locked pico-second laser, enhanced SRS phenomena canbe observed in the 12 cm submicro-diameter fibers with only 1.5 μw pump power. At theend of the thesis, we discuss the application of the submicro-diameter tapered fibres.This work presents the opportunity to reduce the diameter or width of low-loss optical waveguide from wavelength level to subwavelength region. Microphotonic devices assembled with these tapered fibres are expected to have much smaller sizes, which will be promising for many applications such as high-density optical integration, optical communication and optical sensing.
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