Dispositivos fotônicos a partir da micromanipulação das propriedades de fibras ópticas

• Autor(a) principal: Gerosa, Rodrigo Mendes
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: http://dspace.mackenzie.br/handle/10899/24266
• topic: laser de corante; fibra de cristal fotônico (PCF); pós-processamento; rodamina; acoplador óptico; nanotubos de carbono; óxido de grafeno; dye lasers; photonic crystal fiber (PCF); post processing; rhodamine; optical coupler; carbon nanotubes; graphene oxide; CNPQ::ENGENHARIAS::ENGENHARIA ELETRICA

This thesis describes the development of new photonic devices produced by micromanipulation of the optical fibers properties, i.e., the change, in the micrometer scale, of the fiber s optical and/or geometrical properties. In this context, three lines of research have been followed, using different optical fiber processing techniques and considering different types of devices. In the first line, the coupling of two cores in a photonic crystal fiber with three initially uncoupled cores was demonstrated. The couplers had an insertion loss estimated at ~1 dB and exhibited spectral modulations with a depth up to 18 dB. They also showed high sensitivity to polarization, which can be exploited in fiber polarization beamsplitters. For this work, we used a technique that modifies the fiber structure by applying local differential pressure and heating. In the second line, a Rhodamine dye laser was develop with a fully fiber integrated optofluidic cavity. It was possible to maintain a high flow of the dye solution, up to 400 μL / min, which allowed the use of a pump laser with a high repetition rate (1 kHz), and, at the same time, the degradation of the gain medium was not observed. An optical conversion rate of up to 9% and a pump energy threshold lower than 1 mJ were obtained. A splicing technique was used, in which an angled cleaved capillary fiber was fused to a conventional fiber, thereby leaving a side inlet open for the fluid flow. The third line aimed at the incorporation of carbon nanomaterials to optical fibers. In this case, two approaches were employed: in one of them, polymeric films, with a thickness of 20 μm, containing carbon nanotubes were produced on the face of optical fiber patchcords; such patchcords have been inserted into erbium-doped fiber laser cavities to act as saturable absorbers in order to obtain mode-locking operation. Pulses with durations down to 364 fs were obtained with 10.2 nm bandwidths. The films were formed when a micro-droplet of a carbon nanotube suspension on an optical adhesive was placed on the surface of optical fiber connectors, with the use of a micropipette. Within the same line, photonic crystal fibers (PCFs) with homogeneous graphene oxide films covering the inner walls of their capillaries were obtained. The homogeneity was confirmed by Raman spectroscopy and by the loss per fiber length, as measured by the cut back method. A PCF was also spliced to conventional connectorized fiber patchcords and incorporated into a laser cavity to generate pulses. The film production was consisted of inserting a graphene oxide suspension into the PCF capillaries, after which the solvent was dried.