Research On The Mechanisms And Applications Of The Properties Controlling In Functional Materials Filled Microstructured Optical Fibers

The introduction of photonic crystal structure into the fiber cross section of microstructured optical fibers (MOFs) has turned the localization of optical field and control of optical wave propagation into reality. Owing to their distinguished structures and properties that have been exploited in various fiber-optic applications, MOFs have attracted considerable research interests in the past decade. The micro/nano-scale air holes in MOFs make it possible for the combination of optical fibers with functional materials. The outstanding guiding properties of MOFs could be well synthesized with the unique physical characteristics of the optical, electrical, magnetic, and thermal materials infiltrated into MOFs, and thus several optical properties, including guiding mechanism, mode coupling, birefringence, and dispersion, could be controlled, which would be of great significance for the research on the light-matter interaction and development of fiber-based opto-electronic devices as well as sensing components. And moreover, by exploiting the distinguished optical controllability assisted by MOFs, the real-time precise measurement and control could be realized, showing their promising application prospects in various fields such as biophotonics and microfluidic dynamics.Thanks to the support of the National Key Basic Research and Development Program of China, the National Natural Science Foundation of China, the Tianjin Natural Science Foundation. Based on the goal and content of the projects, in this thesis, we have performed systematic as well as in-depth theoretical and experimental investigations on the guiding mechanism, mode control, mode tunability for MOFs infiltrated with high index functional materials. The research work and acquired original outcome are as follows:1. The guiding mechanism, temperature and bending characteristics of the MOFs filled with high index functional materials have been theoretical studied, disclosing the temperature/bending tunability of photonics bandgap and temperature dependence of bending tuning. Simultaneous bending-temperature tuning for the photonic bandgap fiber is proposed, and a wider bandgap tunable range has been achieved compared with the case without applied bending. 2. Based on the theoretical investigation of the mode profile and mode coupling characteristics of the photonic bandgap fiber (PBGF) filled with high index functional material, the avoided-crossing effect between the core mode and high index rod modes have been presented. Owing to this effect, a narrow linewidth resonance peak turns up in the transmission window of the photonic bandgap fiber, and an ultrasensitive refractive index/temperature PBGF sensor has been achieved. Its refractive index and temperature sensitivities reach32400nm/RIU and-13.1nm/℃, respectively, which are the highest values for the fiber sensors reported in related literatures to the best of our knowledge.3. By controlling the splicing parameters between the PBGF filled with high index functional material and single-mode fiber (SMF), an F-P interferometer with18μm in width and40μm in height has been fabricated at the splicing joint. And by employing an optical fiber loop, the transmission spectrum of the PBGF filled with high index material and the reflection spectrum of the microcavity F-P interferometer have been combined to reveal the photonic-bandgap-controlled F-P interferometric fringe loss.Based on the high temperature sensitivity of the photonic bandgap edge, a temperature sensitivity of resonance peak loss as large as-1.94dB/℃has been achieved for our proposed F-P interferometer; by exploiting the highly sensitive spectral response to axial tension, a tension sensitivity of3.25nm/N has been achieved as well. And by using the high temperature sensitivity and low tension sensitivity of the bandgap-controlled interferometric resonance peak loss and the high tension sensitivity and temperature insensitivity of the resonance peak outside the photonic bandgap, simultaneous measurement of temperature and axial tension have been achieved.4. The mode coupling and modal birefringence characteristics of various types of the high-index-filled MOFs with different selective filling configurations and different meterials have been theoretically investigated, revealing the possibility of fiber modal birefringence control through mode coupling between the core mode and high index rod modes, and thus MOFs with unique birefringence feature have been realized. And moreover, the spectral and sensing characteristics of the Sagnac interferometer based on this type of birefringence fiber has been theoretically analyzed, revealing the group-birefringence-and fiber-length-based controllability of interferometric spectrum and sensing characteristics. Theoretical results indicate that ultrahigh sensitivity may be achieved around the resonance peaks with zero group birefringence.5. By using direct manual glue selective filling method and CO2-laser-based side illumination method, the high-index-filled MOFs with different selective filling configurations have been achieved. The interferometric spectrum and sensing characteristics have been experimentally investigated, and experimental results indicate the different spectral and sensing characteristics of the MOF-based Sagnac interferometers with different group birefringence. Their sensitivities show strong temperature responses. The temperature and index sensitivities of-45.8nm/℃and112,531nm/RIU have been achieved at56.5℃, and the tension sensitivity reaches19.6nm/N.