Abstract
This thesis has briefly presented the remarkable work on demonstrating the novel highly efficient double-pass PPLN waveguide Enhancement of the normalized efficiency is verified when compared to the usual single-pass waveguide device. The APE PPLN waveguide with a 40 mm-long QPM section exhibits normalized efficiency of around 23.6 % W-1 cm-2 and the conversion efficiency is about 3.77 % for the single-pass generation with pumping power of 20 mW. The double-pass configuration allows the same device to achieve normalized efficiency of approximately 75.7 % W-1 cm-2 and conversion efficiency of approximately 16.86 %. The conversion efficiency for the double-pass generation can be estimated as 13.85 % using a theoretical approach.The device is also used as an electro-optic (EO) modulator and its electro-optic effects, half-wave voltage and modulation depth are tested. The measured half-wave voltage of the device is about 315 V, and the obtained modulation depths are around 48 % and 60 %, respectively, under different conversion levels.