Integrated optical devices in lithium niobate

• Main Author: Ahmed, Mohammad Jamil
• Language: English
• Published: 2010
• Subjects: Optical instruments; Lithium niobate
• Online Access: http://hdl.handle.net/2429/23459

Integrated optical devices use light to perform circuit functions. One class of devices using Ti indiffused waveguides in LiNb0₃ are investigated in this thesis. The applications studied include series and multibranch interferometers, a comparatorless A/D converter, and a high voltage sensor. An Impedance transformation equation for an exponential line is derived and used to obtain relations for the propagation constant of an optical waveguide with linearly graded index. The results are used to study the effect of a Ta₂O₅ film on the propagation constant of a Ti diffused waveguide. Heating in O₂ of the TA₂0₅ film, loading one arm of the Mach-Zehnder modulator, is shown to tune the modulator. The fabrication of devices in Y-cut LiNb0₃ by Ti diffusion is described. Microscope objectives are used to couple 0.6328 μm light into 4 μm wide waveguides through polished edges. An application of the Mach-Zehnder modulator and a two mode BOA (Bifurcation optique active) modulator to high voltage measurement is discussed. The output Intensity of the series interferometric filter is calculated. Measured results on a two section filter are presented. Also, the output intensity of a multibranch interferometric filter is determined. Experimental results on a three branch filter are included. === Applied Science, Faculty of === Electrical and Computer Engineering, Department of === Graduate