Design And Application Investigation On Material Infused Photonic Crystal Fibers

Along with the development of the fiber technology, more and more applications have been realized regarding photonic crystal fibers (PCF). In present optical communication systems, PCFs still can't replace the traditional optical fiber due to their large attenuation and expensive cost. However, considering their unique optical guiding mechanism and improved optical properties, it is agreed that PCFs will play an important role in the next optical communication systems.In this dissertation, which is supported by the National Natural Science Foundation of China under Grant No. 10674074 and 10774077, supported by the National Key Basic Research and Development Program of China under Grant No. 2003CB314906, and supported by the Tianjin Natural Science Foundation under Grant No. 06YFJZJC00300, the design, numerical analysis and experimental investigation of PCFs and PCF devices are proposed. Particularly, the filling applications of PCFs are majorly investigated, novel PCF devices have been proposed with improved tuning properties. The details are described as follows:1. We investigated the filling technology of PCFs and proposed two novel accesses to realize improved selective filling in a photonic bandgap fiber (PBGF). Meanwhile, by using a lateral erosion method, we proposed a method to improve PCFs'optical properties. The erosion is realized by using hydrofluoric acid to change PBGFs'structure and their optical properties.2. We investigated the properties of PBGF which is realized by temperature responsive polymer's infusion. The bandgap guiding and temperature tunable bandgap transmission have been studied. The temperature tuned bandgap shift is as large as 200nm. We also realized the bandgap compression to narrow a transmission bandgap from 200nm to only 30nm. Especially, we investigated the PBGF's bending loss and find that the polymer infused PBGF has very small bending loss compared with all-solid PBGFs. Besides, the numerical results and the experimental results are in very good agreement. 3. We investigated the bandgap transmission characteristics of the liquid crystal infused PBGF and its tuning properties. The tuning includes the temperature tuning and electrical tuning. We learnt that the temperature tuning of the LC-PBGF is very fast (about 50nm/℃) at temperatures around LC's clearing point. Based on the LC-PBGF, we proposed the first electrically controlled Sagnac interferometer. The Sagnac interference leads to a very good transmission extinction as large as 27dB around 1550nm wavelength. The electrical tuning efficiency is about 1.28nm/V.4. We demonstrated a dual-core PBGF by infusing a high-index liquid into a dual-core air-silica PCF. Extremal couplings have been experimentally observed. The temperature tunable characteristics of the dual-core PBGF's bandgap guiding and dual-core coupling are experimentally and numerically investigated. When we rise temperature, the dual-core PBGFs'bandgaps have been changed: compression of bandwidth, blue-shift and depression of the guiding band. Especially, the dual-core coupling is temperature tunable because of the tunability of the infusion liquid's index. We find that the rise of temperature increases the coupling length which results in the blue-shift of the resonant peak wavelengths with a speed of 1.9nm/℃, for a 20mm dual-core PBGF. Based on the design of this kind of dual-core PBGF, we proposed tunable couplers and MUX/DEMUXs with improved tuning properties and coupling performence.5. We investigated the filling application of quantum dot materials in PCFs. Numerically, we studied the influence of the coating of quantum dots in a PBGF, which indicates strong influences from surface modes. At the same time, we experimentally deposited quantum dots into PCFs. The quantum dots PCFs'emission properties were investigated by using a 130mW LD laser to pump at 980nm wavelength and lasing output has been observed.