Fabrication and applications of zinc indiffused channel waveguides in periodically poled lithium niobate
A comprehensive investigation of high conversion efficiency second harmonic generation (SHG) devices based on zinc indiffused channel waveguides in periodically poled lithium niobate (PPLN) is reported in this thesis. The thesis covers all stages from the production of PPLN by domain inversion on a micron scale through to optical testing. The factors affecting poling quality, such as crystal discrepancies from different suppliers, electrode materials, patterning quality, and mask design, are investigated and analysed systematically. In addition, back-switch poling methods (involving poling a sample completely and then re-poling) are demonstrated. By using optimized processes combining high electric-field poling with the use of conductive liquid gel as an electrode, we have successfully fabricated high quality PPLN samples with short periods (less than 6.5μm), magnesium doped PPLN (PPMgLN), periodically poled lithium tantalate (PPLT), and hexagonally poled lithium niobate (HexLN). for 1552.4nm with 81% conversion for a pulsed source being achieved. Studies of green and blue generation exposed limitations with the technique for shorter wavelength operation, and these are discussed and modelled.