Development of frequency converters with extended functionalities in periodically poled silica fibres

摘要: The centrosymmetry of amorphous silica can be broken through the technique thermal poling, whereby application an electric field at elevated temperatures introduces effective second-order nonlinearity. Quasi-phase-matching is realised periodic ultra-violet erasure uniformly induced A truly all-fibre laser system operating in visible was envisioned to replace crystalline frequency doublers currently employed. Despite lower second-order-nonlinearity poled fibres, longer interaction length for comparable acceptance bandwidths, higher damage threshold and straightforward integration makes them a very attractive substitute. In this thesis, routes taken induce maximum possible nonlinearity optimisation quasi-phase-matching achieve highest normalised conversion efficiency are reported. Periodic allows scalability lengths comparison photolithography previously Further circular twin-hole fibres used instead D-shaped fibres. greater than 16 times improvement over previous results obtained enhancement key parameters length, stability reproducibility. An average ~15% demonstrated ~32cm long periodically fibre using source with just ~200W peak power. functionalities converters have been extended include broadband wavelength tunability 45nm chirped period poling precise control bandwidth.