| Two major topics are discussed in this dissertation. The first one is focused on the use of HgTe quantum dots (QDs) as optical gain medium for a fiber based microlaser with near infrared (NIR) emission above 1300 nm. The negatively charged QDs are deposited onto a tapered fiber using a positively charged polyelectrolyte that covers a small portion of the fiber. Pump light originated from a frequency scanned Ti:Sapphire laser (750 nm – 850 nm) is evanescently coupled into a silica microresontor in contact with the coated fiber. The NIR signal coming from the optically excited QDs is also coupled into the microsphere and is eventually picked up by the coated fiber and processed. Compared to a QD-coated microsphere-based laser, the main features of this microlaser are: higher lasing efficiency, low optical excitation threshold, improved photostability of the QDs in time, and good signal to noise ratio of the NIR signal.;The second part of this work is dedicated to the description, production, and practical use in chemical sensing of silica hollow bottle resonators. The production method for the silica hollow bottle resonator takes advantage of commonly available items in the Optics lab: H2-O2 jeweler's torch, off-the-shelf capillaries, HF, and syringe pump. Specifically, the bottle-shaped resonators are obtained by exposing the middle region of a compressed-air-filled thin capillary to a H2 or H2-O 2 flame. Since these resonators feature a central wall thickness of about 5 µm or less, they are suitable for sensing of NIR-active dyes and gases. Moreover, it is shown that silica hollow bottle resonators can be successfully used in pH detection using a swellable polymer as a mediator in the sensing process. |
