Waveguide Characteristics Of Subwavelength-diameter Optical Fibers

Microelectronics, optoelectronics and photonics play an important role in the modern optical communication and optical sensor industry. With the development of the design theory and preparation techniques, and the requirements of device performance, integration and energy cost, the width or length of devices in microelectronics and optoelectronics have been decreased to sub-micrometer or nanometer. It is well known that the optical fiber has the maximum bandwidth in all transmitting medium used in the network communications. In the past 30 years, the width or length of the dielectric waveguide have been thinned or shortened from millimeter to nanometer, which facilitates its application in optical communication, optical fiber sensing, optical power delivery system and so on. However, how to prepare the low loss waveguide is still a challenge to all of us. In recent years, optical fibers with sub-micrometer or nanometer core size have been prepared successfully, which lay a foundation for the future sub-micrometer or nanometer optical devices. Among all the applications, the most important and basic thing is to study the waveguide characteristics of such optical fibers. Based on the previous works, the thesis has focused on studying the waveguide characteristics of single subwavelength-diameter optical fiber and the fiber array using electromagnetic computation methods. By theoretical simulation, some innovative and important results have been achieved.The waveguide characteristics of single subwavelength-diameter optical fibers, including solid core and hollow core, have been modeled and analyzed. By adjusting the fiber parameters, the subwavelength-diameter solid core or hollow core optical fibers have large evanescent field. For the subwavelength-diameter hollow optical fiber, besides the large evanescent field in the outer cladding, it has enhanced intensity in the central hollow region. By varying the size of central hollow region, the modal field and waveguide dispersion can be adjusted. The unqiue characteristics of the subwavelength-diameter hollow optical fiber may have many applications in atom optics, optical fiber sensing and so on.The coupling characteristics and modal shaping abilities of multiple subwavelength-diameter optical fibers have been studied. Based on the large evanescent field of subwavelength-diameter optical fiber, by using finite-difference time-domain (FDTD) method, the coupling characteristics and modal shaping abilities of multiple subwavelength-diameter optical fibers, including solid core and hollow core, have been simulated. The results justify that the subwavelength-diameter optical fiber can combine with each other efficiently. All the features may provide applications in high-speed optical communications, optical delivery system, etc.